Merck Manual

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Breast Cancer

By

Mary Ann Kosir

, MD, Wayne State University School of Medicine

Last full review/revision Oct 2019| Content last modified Oct 2019
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Breast cancer occurs when cells in the breast become abnormal and divide uncontrollably. Breast cancer usually starts in the glands that produce milk (lobules) or the tubes (ducts) that carry milk from the glands to the nipple.

  • Among women, breast cancer is the most common cancer and the second most common cause of cancer deaths.

  • Typically, the first symptom is a painless lump, usually noticed by the woman.

  • Breast cancer screening recommendations vary and include periodic mammography, breast examination by a doctor, and breast self-examination.

  • If a solid lump is detected, doctors use a hollow needle to remove a sample of tissue or make an incision and remove part or all of the lump and then examine the tissue under a microscope (biopsy).

  • Breast cancer almost always requires surgery, sometimes with radiation therapy, chemotherapy, other drugs, or a combination.

  • Outcome is hard to predict and depends partly on the characteristics and spread of the cancer.

Breast disorders may be noncancerous (benign) or cancerous (malignant). Most are noncancerous and not life threatening. Often, they do not require treatment. In contrast, breast cancer can mean loss of a breast or of life. Thus, for many women, breast cancer is their worst fear. However, potential problems can often be detected early when women regularly examine their breasts themselves, are examined regularly by their doctor, and have mammograms as recommended. Early detection of breast cancer can be essential to successful treatment.

Breast cancer is the most common cancer among women and, of cancers, is the most common cause of death among Hispanic women and the second most common cause of death in women of other races (after lung cancer). Experts estimate that in 2019 in the United States, the following is expected:

Breast cancers in men account for about 1% of all breast cancers.

Many women fear breast cancer, partly because it is common. However, some of the fear about breast cancer is based on misunderstanding. For example, the statement, “One of every eight women will get breast cancer,” is misleading. That figure is an estimate based on women from birth to age 95. It means that theoretically, one of eight women who live to age 95 or older will develop breast cancer. However, a 40-year-old woman has only about a 1 in 70 chance of developing it during the next decade. But as she ages, her risk increases.

Table
icon

What Are the Risks of Developing Breast Cancer?

Age (Years)

Risk (%) in 10 Years

Risk (%) in 20 Years

Risk (%) in 30 Years

30

0.5

2.0

4.3

40

1.5

3.8

7.1

50

2.4

5.7

9.1

60

3.5

7.1

9.2

70

4.1

6.4

Based on the seer.cancer.gov web site. Accessed on 10/16/19.

Risk Factors for Breast Cancer

Several factors affect the risk of developing breast cancer. Thus, for some women, the risk is much higher or lower than average. Most factors that increase risk, such as age and certain abnormal genes, cannot be modified. However, regular exercise, particularly during adolescence and young adulthood may reduce the risk of developing breast cancer.

Far more important than trying to modify risk factors is being vigilant about detecting breast cancer so that it can be diagnosed and treated early, when it is more likely to be cured. Early detection is more likely when women have mammograms. Regular breast self-examinations are also recommended by some doctors, although these examinations have not been shown to reduce risk of death from breast cancer.

Age

Increasing age is the most important risk factor for breast cancer. Most breast cancers occur in women older than 50. Risk is greatest after age 75.

Previous history of breast cancer

Having had breast cancer increases the risk of breast cancer. After the diseased breast is removed, the risk of developing cancer in the remaining breast is about 0.5 to 1.0% each year.

Family history of breast cancer

Breast cancer in a first-degree relative (mother, sister, or daughter) increases a woman’s risk by 2 to 3 times, but breast cancer in more distant relatives (grandmother, aunt, or cousin) increases the risk only slightly. Breast cancer in two or more first-degree relatives increases a woman’s risk by 5 to 6 times.

Breast cancer gene mutation

Mutations in two separate genes for breast cancer (BRCA1 and BRCA2) have been identified. Fewer than 1% of women have these gene mutations. About 5 to 10% of women with breast cancer have one of these gene mutations. If a woman has one of these mutations, her chances of developing breast cancer are high, possibly as high as 46 to 72% during her lifetime. However, if such a woman develops breast cancer, her chances of dying of breast cancer are not necessarily greater than those of any other woman with breast cancer.

These mutations are most common among Ashkenazi Jews.

Women likely to have one of these mutations are those who have at least two close, usually first-degree relatives who have had breast or ovarian cancer. For this reason, routine screening for these mutations does not appear necessary, except in women who have such a family history.

Having either of the breast cancer gene mutations also increases the risk of ovarian cancer.

The risk of breast cancer is increased in men with the BRCA2 gene mutation.

Women with one of these mutations may need to be tested more frequently for breast cancer. Or they may need to try to prevent cancer from developing by taking tamoxifen or raloxifene (which is similar to tamoxifen) or sometimes by even having both breasts removed (double mastectomy).

Did You Know...

  • Fewer than 1% of women have the gene mutations for breast cancer.

Certain benign changes in the breast

Some changes in the breast seem to increase risk of breast cancer. They include

  • Changes in the breast that required a biopsy to rule out cancer

  • Conditions that change the structure, increase the number of cells, or cause lumps or other abnormalities in breast tissue, such as complex fibroadenoma, hyperplasia (abnormally increased growth of tissue), atypical hyperplasia (hyperplasia with abnormal tissue structure) in the milk ducts or milk-producing glands, sclerosing adenosis (increased growth of tissue in the milk-producing glands), or papilloma (a noncancerous tumor with fingerlike projections)

  • Dense breast tissue, seen on a mammogram

Having dense breast tissue also makes it harder for doctors to identify breast cancer.

For women with such changes, the risk of breast cancer is increased only slightly unless abnormal tissue structure is detected during a biopsy or they have a family history of breast cancer.

Age at first menstrual period, first pregnancy, and menopause

The earlier menstruation begins (especially before age 12), the higher the risk of developing breast cancer.

The later the first pregnancy occurs and the later menopause occurs, the higher the risk. Never having had a baby increases the risk of developing breast cancer. However, women who have their first pregnancy after age 30 are at higher risk than those who never have a baby.

These factors probably increase risk because they involve longer exposure to estrogen, which stimulates the growth of certain cancers. (Pregnancy, although it results in high estrogen levels, may reduce the risk of breast cancer.)

Oral contraceptives or hormonal therapy

Taking oral contraceptives for a long time increases the risk of later developing breast cancer, but only very slightly. After women stop taking contraceptives, the risk gradually decreases over the next 10 years to that for other women of the same age.

After menopause, taking combination hormone therapy (estrogen with a progestin) for a few years or more increases the risk of breast cancer. Taking estrogen alone does not appear to increase the risk of breast cancer.

Diet and obesity

Diet may contribute to the development or growth of breast cancers, but evidence about the effect of a particular diet (such as a high-fat diet) is lacking (see also Diet and Cancer).

Risk of developing breast cancer is somewhat higher for women who are obese after menopause. Fat cells produce estrogen, possibly contributing to the increased risk. However, there is no proof that a high-fat diet contributes to the development of breast cancer or that changing the diet can decrease risk. Some studies suggest that obese women who are still menstruating are less likely to develop breast cancer.

Research about the link between obesity and cancer is ongoing (see also the National Cancer Institute: Uncovering the Mechanisms Linking Obesity and Cancer Risk).

Lifestyle

Smoking and regularly drinking alcoholic beverages may increase the risk of breast cancer. Experts recommend that women limit themselves to one alcoholic drink a day. One drink is about 12 ounces of beer, 5 ounces of wine, or 1.5 ounces of more concentrated liquor, such as whiskey.

Radiation exposure

Radiation exposure (such as radiation therapy for cancer or significant exposure to x-rays) before age 30 increases risk.

Types of Breast Cancer

Breast cancer is usually classified by the following:

  • The kind of tissue in which the cancer starts

  • The extent of the cancer's spread

  • The type of tumor receptors on the cancer cells

Kind of tissue

There are many different kinds of tissue in the breast. Cancer can develop in most of these tissues, including

  • Milk ducts (called ductal carcinoma)

  • Milk-producing glands, or lobules (called lobular carcinoma)

  • Fatty or connection tissue (called sarcoma): This type is rare.

Ductal carcinoma accounts for about 90% of all breast cancers.

Paget disease of the nipple is a ductal breast carcinoma that affects the skin over and around the nipple. The first symptom is a crusty or scaly nipple sore or a discharge from the nipple. Slightly more than half of the women who have this cancer also have a lump in the breast that can be felt. Women with Paget disease of the nipple may also have another type of breast cancer. Because this disease usually causes little discomfort, women may ignore it for a year or more before seeing a doctor. The prognosis depends on how invasive and how large the cancer is as well as whether it has spread to the lymph nodes.

Phyllodes breast tumors are relatively rare, accounting for fewer than 1% of breast cancers. About half are cancerous. They originate in breast tissue around milk ducts and milk-producing glands. The tumor spreads to other parts of the body (metastasizes) in about 10 to 20% of women who have it. It recurs in the breast in about 20 to 35% of women who have had it. The prognosis is good unless the tumor has metastasized.

Extent of spread

Breast cancer can remain within the breast or spread anywhere in the body through the lymphatic vessels or bloodstream. Cancer cells tend to move into the lymphatic vessels in the breast. Most lymphatic vessels in the breast drain into lymph nodes in the armpit (axillary lymph nodes). One function of lymph nodes is to filter out and destroy abnormal or foreign cells, such as cancer cells. If cancer cells get past these lymph nodes, the cancer can spread to other parts of the body.

Breast cancer tends to spread to bones and the brain but can spread to any area, including the lungs, liver, skin, and scalp. Breast cancer can appear in these areas years or even decades after it is first diagnosed and treated. If the cancer has spread to one area, it probably has spread to other areas, even if it cannot be detected right away.

Breast cancer can be classified as

  • Carcinoma in situ

  • Invasive cancer

Carcinoma in situ means cancer in place. It is the earliest stage of breast cancer. Carcinoma in situ may be large and may even affect a substantial area of the breast, but it has not invaded the surrounding tissues or spread to other parts of the body.

Ductal carcinoma in situ is confined to the milk ducts of the breast. It does not invade surrounding breast tissue, but it can spread along the ducts and gradually affect a substantial area of the breast. This type accounts for 85% of carcinoma in situ and 20 to 30% of breast cancers. It is detected most often by mammography. This type may become invasive.

Lobular carcinoma in situ develops within the milk-producing glands of the breast (lobules). It often occurs in several areas of both breasts. Women with lobular carcinoma in situ have a 1 to 2% chance each year of developing invasive breast cancer in the affected or the other breast. Lobular carcinoma in situ accounts for 1 to 2% of breast cancers. Usually, lobular carcinoma in situ cannot be seen on a mammogram and is detected only by biopsy. There are two types of lobular carcinoma in situ: classic and pleomorphic. The classic type is not invasive, but having it increases the risk of developing invasive cancer in either breast. The pleomorphic type leads to invasive cancer and, when detected, is surgically removed.

Invasive cancer can be classified as follows:

  • Localized: The cancer has invaded surrounding tissues but is confined to the breast.

  • Regional: The cancer has invaded tissues near the breasts, such as the chest wall or lymph nodes.

  • Distant (metastatic): The cancer has spread from the breast to other parts of the body (metastasized).

Invasive ductal carcinoma begins in the milk ducts but breaks through the wall of the ducts, invading the surrounding breast tissue. It can also spread to other parts of the body. It accounts for about 80% of invasive breast cancers.

Invasive lobular carcinoma begins in the milk-producing glands of the breast but invades surrounding breast tissue and spreads to other parts of the body. It is more likely than other types of breast cancer to occur in both breasts. It accounts for most of the rest of invasive breast cancers.

Rare types of invasive breast cancers include

  • Medullary carcinoma

  • Tubular carcinoma

  • Metaplastic carcinoma

  • Mucinous carcinoma

Mucinous carcinoma tends to develop in older women and to be slow growing. Women with these rare types of breast cancer have a much better prognosis than women with other types of invasive breast cancer.

Tumor receptors

All cells, including breast cancer cells, have molecules on their surfaces called receptors. A receptor has a specific structure that allows only particular substances to fit into it and thus affect the cell’s activity. Whether breast cancer cells have certain receptors affects how quickly the cancer spreads and how it should be treated.

Tumor receptors include the following:

  • Estrogen and progesterone receptors: Some breast cancer cells have receptors for estrogen. The resulting cancer, described as estrogen receptor–positive, grows or spreads when stimulated by estrogen. This type of cancer is more common among postmenopausal women than among younger women. About two thirds of postmenopausal women with cancer have estrogen receptor–positive cancer. Some breast cancer cells have receptors for progesterone. The resulting cancer, described as progesterone receptor–positive, is stimulated by progesterone. Breast cancers with estrogen receptors and possibly those with progesterone receptors grow more slowly than those that do not have these receptors, and the prognosis is better. (Estrogen and progesterone are female sex hormones.)

  • HER2 (HER2/neu) receptors: Normal breast cells have HER2 receptors, which help them grow. (HER stands for human epithelial growth factor receptor, which is involved in multiplication, survival, and differentiation of cells.) In about 20% of breast cancers, cancer cells have too many HER2 receptors. Such cancers tend to be very fast growing.

Other characteristics

Sometimes cancer is also classified based on other characteristics.

Inflammatory breast cancer is an example. The name refers to the symptoms of the cancer rather than the affected tissue. This type is fast growing and often fatal. Cancer cells block the lymphatic vessels in the skin of the breast, causing the breast to appear inflamed: swollen, red, and warm. Usually, inflammatory breast cancer spreads to the lymph nodes in the armpit. The lymph nodes can be felt as hard lumps. However, often no lump may be felt in the breast itself because this cancer is dispersed throughout the breast. Inflammatory breast cancer accounts for about 1% of breast cancers.

Symptoms

At first, breast cancer causes no symptoms.

Most commonly, the first symptom of breast cancer is a lump, which usually feels distinctly different from the surrounding breast tissue. In many breast cancer cases, women discover the lump themselves. Such a lump may be cancer if it is a firm, distinctive thickening that appears in one breast but not the other. Usually, scattered lumpy changes in the breast, especially the upper outer region, are not cancerous and indicate fibrocystic changes.

Breast pain is not usually the first symptom of breast cancer.

In the early stages, the lump may move freely beneath the skin when it is pushed with the fingers.

In more advanced stages, the lump usually adheres to the chest wall or the skin over it. In these cases, the lump cannot be moved at all or it cannot be moved separately from the skin over it. Sometimes women can determine whether they have a cancer that even slightly adheres to the chest wall or skin by lifting their arms over their head while standing in front of a mirror. If a breast contains cancer that adheres to the chest wall or skin, this maneuver may make the skin pucker or dimple or make one breast appear different from the other.

In very advanced cancer, swollen bumps or festering sores may develop on the skin. Sometimes the skin over the lump is dimpled and leathery and looks like the skin of an orange (peau d’orange) except in color.

The lump may be painful, but pain is an unreliable sign. Pain without a lump is rarely due to breast cancer.

If the cancer has spread, lymph nodes, particularly those in the armpit on the affected side, may feel like hard small lumps. The lymph nodes may be stuck together or adhere to the skin or chest wall. They are usually painless but may be slightly tender.

Occasionally, the first symptom occurs only when the cancer spreads to another organ. For example, if it spreads to a bone, the bone may ache or become weak, resulting in a fracture. If the cancer spreads to a lung, women may cough or have difficulty breathing.

In inflammatory breast cancer, the breast is warm, red, and swollen, as if infected (but it is not). The skin of the breast may become dimpled and leathery, like the skin of an orange, or may have ridges. The nipple may turn inward (invert). A discharge from the nipple is common. Often, no lump can be felt in the breast, but the entire breast is enlarged.

Screening

Because breast cancer rarely causes symptoms in its early stages and because early treatment is more likely to be successful, screening is important. Screening is the hunt for a disorder before any symptoms occur.

Screening for breast cancer may include

  • Monthly breast self-examination

  • Yearly breast examination by a health care practitioner

  • Mammography

  • If women have an increased risk of breast cancer, magnetic resonance imaging (MRI)

Concerns about screening for breast cancer

People may think that any test capable of diagnosing a serious disorder should be done. However, this notion is not true. Although screening has great benefits, it can also create problems. For example, screening tests for breast cancer sometimes indicate a cancer is present when no cancer is present (called a false-positive result). When results of a breast screening test are positive, a breast biopsy is usually done. Having a false-positive result means having a biopsy that is not needed and being exposed to unnecessary anxiety, pain, and expense.

On the other hand, screening tests may not detect cancer that is present (called a false-negative result). A false-negative result may give women false reassurance and cause them to disregard later symptoms that would otherwise have sent them to their doctor.

Also, doctors are learning that some abnormalities, identified by a breast biopsy, appear to be cancerous but do not need to be treated.

Because of these concerns, doctors are trying to limit the use of screening tests. However, different doctors and different medical organizations do not all agree on exactly which screening tests should be done and when (see table Breast Cancer: When to Start Screening Mammography?). Women should discuss their individual risk with their doctor, and they and their doctor should decide which type of screening, if any, is appropriate for them.

Breast self-examination

In the past, most doctors recommended that women examine their breasts for lumps each month. The thought was that routine self-examination would detect lumps that might be cancer at an early stage.

However, self-examination alone does not reduce the death rate from breast cancer, and it does not detect as many early cancers as routine screening with mammography. Because self-examination may not detect all lumps, women who do not detect any lumps should continue to see their doctor and to have mammograms as recommended.

How to Do a Breast Self-Examination

1. While standing in front of a mirror, look at the breasts. The breasts normally differ slightly in size. Look for changes in the size difference between the breasts and changes in the nipple, such as turning inward (an inverted nipple) or a discharge. Look for puckering or dimpling.

How to Do a Breast Self-Examination

2. Watching closely in the mirror, clasp the hands behind the head and press them against the head. This position helps make subtle changes caused by cancer more noticeable. Look for changes in the shape and contour of the breasts, especially in the lower part of the breasts.

How to Do a Breast Self-Examination

3. Place the hands firmly on the hips and bend slightly toward the mirror, pressing the shoulders and elbows forward. Again, look for changes in shape and contour.

How to Do a Breast Self-Examination

Many women do the next part of the examination in the shower because the hand moves easily over wet, slippery skin.

How to Do a Breast Self-Examination

4. Raise the left arm. Using three or four fingers of the right hand, probe the left breast thoroughly with the flat part of the fingers. Moving the fingers in small circles around the breast, begin at the nipple and gradually move outward. Press gently but firmly, feeling for any unusual lump or mass under the skin. Be sure to check the whole breast. Also, carefully probe the armpit and the area between the breast and armpit for lumps.

How to Do a Breast Self-Examination

5. Squeeze the left nipple gently and look for a discharge. (See a doctor if a discharge appears at any time of the month, regardless of whether it happens during breast self-examination.)

Repeat steps 4 and 5 for the right breast, raising the right arm and using the left hand.

6. Lie flat on the back with a pillow or folded towel under the left shoulder and with the left arm overhead. This position flattens the breast and makes it easier to examine. Examine the breast as in steps 4 and 5. Repeat for the right breast.

How to Do a Breast Self-Examination

Women who choose to examine their breasts should do so at the same time each month. For menstruating women, 2 or 3 days after their period ends is a good time because the breasts are less likely to be tender and swollen. Postmenopausal women may choose any day of the month that is easy to remember, such as the first.

Adapted from a publication of the National Cancer Institute.

Breast examination by a health care practitioner

A breast examination may be part of a routine physical examination. However, as with breast self-examination, a doctor's examination may miss a cancer. If women need or want screening, a more sensitive test, such as mammography, should be done, even if a doctor's examination did not detect any abnormalities. Many doctors and medical organizations no longer require an annual breast examination by a doctor.

During the examination, a doctor inspects the breasts for irregularities, dimpling, tightened skin, lumps, and a discharge. The doctor feels (palpates) each breast with a flat hand and checks for enlarged lymph nodes in the armpit—the area most breast cancers invade first—and above the collarbone. Normal lymph nodes cannot be felt through the skin, so those that can be felt are considered enlarged. However, noncancerous conditions can also cause lymph nodes to enlarge. Lymph nodes that can be felt are checked to see if they are abnormal.

Mammography

For mammography, x-rays are used to check for abnormal areas in the breast. A technician positions the woman’s breast on top of an x-ray plate. An adjustable plastic cover is lowered on top of the breast, firmly compressing the breast. Thus, the breast is flattened so that the maximum amount of tissue can be imaged and examined. X-rays are aimed downward through the breast, producing an image on the x-ray plate. Two x-rays are taken of each breast in this position. Then plates may be placed vertically on either side of the breast, and x-rays are aimed from the side. This position produces a side view of the breast.

Mammography: Screening for Breast Cancer

Mammography: Screening for Breast Cancer

Mammography is one of the best ways to detect breast cancer early. Mammography is designed to be sensitive enough to detect the possibility of cancer at an early stage, sometimes years before it can be felt. Because mammography is so sensitive, it may indicate cancer when none is present—a false-positive result. About 85 to 90% of abnormalities detected during screening (that is, in women with no symptoms or lumps) are not cancer. Typically, when the result is positive, more specific follow-up procedures, usually a breast biopsy, are scheduled to confirm the result. Mammography may miss up to 15% of breast cancers. It is less accurate in women with dense breast tissue.

Breast tomosynthesis (3-dimensional mammography) may be used with mammography to produce a clear, highly focused 3-dimensional picture of the breast. This technique makes it somewhat easier to detect cancer, especially in women with dense breast tissue. However, this type of mammography exposes women to almost twice as much radiation as traditional mammography.

Recommendations for routine screening with mammography vary. Experts disagree about

  • When it should start

  • How often it should be done

  • When (or if) it should be stopped

Screening mammography is recommended for all women starting at age 50, but some experts recommend starting at age 40 or 45. Whenever it is started, mammography is then repeated every 1 or 2 years. Experts have different recommendations about when to start routine mammography because the benefit of screening is not as clear in women aged 40 to 49. Experts are also concerned about starting screening too soon or screening too often because exposure to radiation would be increased and because tumors that would not develop into invasive cancer during the woman's lifetime may be treated unnecessarily.

Women with risk factors for breast cancer are more likely to benefit from starting mammography before age 50. They should discuss the risks and benefits of screening mammograms with their doctor.

Routine mammography may be stopped at age 75, depending on the woman's life expectancy and her wish for continued screening.

Mammography is more accurate in older women, partly because as women age, the amount of fatty tissue in breasts increases, and abnormal tissue is easier to distinguish from fatty tissue than other types of breast tissue.

Did You Know...

  • Only about 10 to 15% of the abnormalities detected during routine screening with mammography turn out to be cancer.

The dose of radiation used is very low and is considered safe.

Mammography may cause some discomfort, but the discomfort lasts only a few seconds. Mammography should be scheduled at a time during the menstrual period when the breasts are less likely to be tender.

Deodorants and powders should not be used on the day of the procedure because they can interfere with the image obtained. The entire procedure takes about 15 minutes.

Breast Cancer: When to Start Screening Mammography?

Experts sometimes disagree about when regular screening with mammography should be started. Because screening identifies cancer and cancers can be fatal, people might think that screening should be started sooner (at age 40) rather than later (at age 50). However, screening has some disadvantages, and the benefits for younger women are not as clear as those for older women.

The following are some reasons for the controversy:

  • Screening, particularly in younger women, detects abnormalities that may not be cancers. Finding an abnormality often results in a biopsy to determine what it is. Thus, screening results in many more breast biopsies, sometimes causing women unnecessary anxiety and expense, as well as possibly resulting in scar tissue in the breast.

  • Some breast cancers, such as in situ breast cancers (cancers that have not spread), are not fatal. Some breast cancers grow slowly and would not cause death in a woman's lifetime. However, other breast cancers continue to grow and invade other tissues. How many of the cancers detected by screening would eventually be fatal is unclear. Nonetheless, all cancers are treated because currently, health care practitioners do not have enough evidence to determine which ones should be treated and which ones should not be treated.

  • Mammography is less accurate in younger women. Thus, screening may miss cancers, possibly including those that could be fatal.

  • Many women must be screened to save one life. When women are older, fewer women need to be screened to save a life. For women 50 and over, screening saves lives and is recommended.

Magnetic resonance imaging

MRI is usually used to screen women with a high risk of breast cancer, such as those with a BRCA mutation. For these women, screening should also include mammography and breast examination by a health care practitioner.

Diagnosis

  • Mammography

  • Breast examination

  • Biopsy

  • Sometimes ultrasonography

When a lump or another abnormality is detected in the breast during a physical examination or by a screening procedure, other procedures are necessary.

Mammography is usually done first if it was not the way the abnormality was detected. Mammography provides a reference for future comparison. It can also help identify tissue that should be removed and examined under a microscope (biopsied).

If doctors suspect advanced cancer based on results of a physical examination, a biopsy is done first. Otherwise, the evaluation is the same as evaluation of a breast lump.

Ultrasonography is sometimes used to help distinguish between a fluid-filled sac (cyst) and a solid lump. This distinction is important because cysts are usually not cancerous. Cysts may be monitored (with no treatment) or drained (aspirated) with a small needle and syringe. The fluid from the cyst is examined to check for cancer cells only if any of the following occurs:

  • The fluid is bloody or cloudy.

  • Little fluid is obtained.

  • The lump remains after it is drained.

Otherwise, the woman is checked again in 4 to 8 weeks. If the cyst can no longer be felt at this time, it is considered noncancerous. If it has reappeared, it is drained again, and the fluid is examined under a microscope. If the cyst reappears a third time or if it is still present after it was drained, a biopsy is done. Rarely, when cancer is suspected, cysts are removed.

Breast biopsy

If the abnormality is a solid lump, which is more likely to be cancerous, a sample of tissue is biopsied to check for cancer cells.

Doctors may do one of several types of biopsy:

  • Core needle biopsy: A wide, hollow needle with a special tip is used to remove a sample of breast tissue.

  • Open (surgical) biopsy: Doctors make a small cut in the skin and breast tissue and remove part or all of a lump. This type of biopsy is done when a needle biopsy is not possible (for example, because no lump is felt). It may also be done after a needle biopsy that does not detect cancer to be sure that the needle biopsy did not miss a cancer.

Imaging is often done during a biopsy to help doctors determine where to place the biopsy needle. Using imaging to guide biopsy improves the accuracy of a core needle biopsy.

For example, if a solid lump is felt, ultrasonography can be used during the core needle biopsy to help doctors locate the abnormal tissue.

When an abnormality is seen only on an MRI scan, MRI is used to guide the placement of the biopsy needle.

A stereotactic biopsy is being done more and more often. It helps doctors accurately locate and remove a sample of the abnormal tissue. For a stereotactic biopsy, doctors take mammograms from two angles and send the two-dimensional images to a computer. The computer compares them and calculates the precise location of the abnormality in three dimensions.

When imaging is used to guide placement of the needle, a clip to mark the spot is typically placed during the biopsy.

The biopsied tissue is x-rayed, and the x-ray is compared with the prebiopsy mammogram to determine whether all of the abnormal tissue was removed. Mammography may be done 6 to 8 weeks after the biopsy to check for any bits of abnormal tissue that was missed.

Most women do not need to be hospitalized for these procedures. Usually, only a local anesthetic is needed.

If Paget disease of the nipple is suspected, a biopsy of nipple tissue is usually done. Sometimes this cancer can be diagnosed by examining a sample of the nipple discharge under a microscope.

A pathologist examines the biopsy samples under the microscope to determine whether cancer cells are present. Generally, a biopsy confirms cancer in only a few women with an abnormality detected during mammography.

If cancer cells are detected, the biopsy sample is analyzed to determine the characteristics of the cancer cells, such as

  • Whether the cancer cells have estrogen or progesterone receptors

  • How many HER2 receptors are present

  • How quickly the cancer cells are dividing

  • For some types of breast cancer, genetic testing of the cancer cells (multigene panels)

This information helps doctors estimate how rapidly the cancer may spread and which treatments are more likely to be effective.

Evaluation after cancer diagnosis

After cancer is diagnosed, doctors usually consult a team of cancer specialists (oncologists), including surgeons, cancer drug treatment specialists, and radiologists (called a tumor board), to determine which tests should be done and to plan treatment.

Tests may include

  • A chest x-ray to determine whether the cancer has spread

  • Blood tests, including a complete blood count (CBC), liver function tests, and measurement of calcium, also to determine whether the cancer has spread

  • In women with risk factors for BRCA genes, analysis of blood or saliva to check for these genes

  • Sometimes bone scanning (imaging of bones throughout the body), computed tomography (CT) of the abdomen and chest, and MRI

Staging

When cancer is diagnosed, a stage is assigned to it. The stage is a number from 0 to IV (sometimes with substages indicated by letters) that reflects how extensive and aggressive the cancer is:

  • Stage 0 is assigned to in situ breast cancers, such as ductal carcinoma in situ. In situ means cancer in place. That is, the cancer has not invaded surrounding tissues or spread to other parts of the body.

  • Stages I through III are assigned to cancer that has spread to tissues within or near the breast (localized or regional breast cancer).

  • Stage IV is assigned to metastatic breast cancer (cancer that has spread from the breast and lymph nodes in the armpit to other parts of the body).

Staging the cancer helps doctors determine the appropriate treatment and the prognosis.

Many factors go into determining the stage of breast cancer, such as the TNM classification system.

The TNM classification is based on the following:

  • Tumor size and extent (T): The size of the cancer, scored from 0 to 4

  • Lymph node involvement (N): The extent cancer has spread to lymph nodes, scored from 1 to 3

  • Metastasis (M): Whether the cancer has spread (metastasized) to other organs, scored as 0 (none) or 1 (has spread)

Other important staging factors include the following:

  • Grade: How abnormal the cancer cells look under a microscope, scored from 1 to 3

  • Hormone receptor status: Whether the cancer cells have estrogen, progesterone, and/or HER2 receptors

  • Genetic testing of the cancer (such as the Oncotype DX test): For some breast cancers, how many and which abnormal genes are present in the cancer

Grade varies because although all cancer cells look abnormal, some look more abnormal than others. If the cancer cells do not look very different from normal cells, the cancer is considered well-differentiated. If the cancer cells look very abnormal, they are considered undifferentiated or poorly differentiated. Well-differentiated cancers tend to grow and spread more slowly than undifferentiated or poorly differentiated cancers. Based on these and other differences in microscopic appearance, doctors assign a grade to most cancers.

The presence of hormone receptors and abnormal genes in the cancer cells affect how the cancer responds to different treatments and what the prognosis is.

The woman's doctor discusses the stage of the cancer with her and explains what it means in terms of treatment and outcome.

Prognosis

Generally, a woman's prognosis depends on

  • How invasive and how large the cancer is

  • What type of cancer it is

  • Whether it has spread to the lymph nodes

(See also the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) Program.)

The number and location of lymph nodes that contain cancer cells is one of the main factors that determine whether the cancer can be cured and, if not, how long women will live.

The 5-year survival rate for breast cancer (the percentage of women who are alive 5 years after diagnosis) is

  • 98.8% if the cancer remains at its original site (localized)

  • 85.5% if the cancer has spread to nearby lymph nodes but no further (regional)

  • 27.4% if the cancer has spread to distant sites (metastasized)

  • 54.5% if the cancer has not been staged

Women with breast cancer tend to have a worse prognosis if they have any of the following:

  • Diagnosis of breast cancer during their 20s and 30s

  • Larger tumors

  • Cancer that has rapidly dividing cells, such as tumors that do not have well-defined borders or cancer that is dispersed throughout the breast

  • Tumors that do not have estrogen or progesterone receptors

  • Tumors that have too many HER2 receptors

  • A BRCA1 gene mutation

Having the BRCA2 gene mutation probably does not make the current cancer result in a worse outcome. However, having either BRCA gene mutation increases the risk of developing a second breast cancer.

Prevention

Taking drugs that decrease the risk of breast cancer (chemoprevention) may be recommended for the following women:

  • Those who are over age 35 and have had a previous lobular carcinoma in situ or abnormal tissue structure (atypical hyperplasia) in the milk ducts or milk-producing glands

  • Those who have a BRCA1 or BRCA2 gene mutation

  • Those who have a high risk of developing breast cancer based on their current age, age when menstruation began (menarche), age at the first birth of a child, number of first-degree relatives with breast cancer, and results of prior breast biopsies

Chemoprevention drugs include

  • Tamoxifen

  • Raloxifene

Women should ask their doctor about possible side effects before beginning chemoprevention.

Risks of tamoxifen include

These risks are higher for older women.

Raloxifene appears to be about as effective as tamoxifen in postmenopausal women and to have a lower risk of endometrial cancer, blood clots, and cataracts.

Both drugs may also increase bone density and thus benefit women who have osteoporosis.

Treatment

  • Surgery

  • Radiation therapy

  • Hormone-blocking drugs, chemotherapy, or both

Usually, treatment for breast cancer begins after the woman’s condition has been thoroughly evaluated, about a week or more after the biopsy.

Treatment options depend on the stage and type of breast cancer and the receptors that the cancer has. However, treatment is complex because the different types of breast cancer differ greatly in characteristics such as growth rate, tendency to spread (metastasize), and response to various treatments. Also, much is still unknown about breast cancer. Consequently, doctors may have different opinions about the most appropriate treatment for a particular woman.

The preferences of a woman and her doctor affect treatment decisions. Women with breast cancer should ask for a clear explanation of what is known about the cancer and what is still unknown, as well as a complete description of treatment options. Then, they can consider the advantages and disadvantages of the different treatments and accept or reject the options offered. Losing some or all of a breast can be emotionally traumatic. Women must consider how they feel about this treatment, which can deeply affect their sense of wholeness and sexuality.

Doctors may ask women with breast cancer to participate in research studies investigating a new treatment. New treatments aim to improve the chances of survival or quality of life. All women who participate in a research study are treated because a new treatment is compared with other effective treatments. Women should ask their doctor to explain the risks and possible benefits of participation, so that they can make a well-informed decision.

Treatment usually involves surgery and often includes radiation therapy and chemotherapy or hormone-blocking drugs. Women may be referred to a plastic or reconstruction surgeon, who can remove the cancer and reconstruct the breast in the same operation.

Surgery

The cancerous tumor and varying amounts of the surrounding tissue are removed. There are two main options for removing the tumor:

  • Breast-conserving surgery

  • Removal of the breast (mastectomy)

For women with invasive cancer (stage I or higher), mastectomy is no more effective than breast-conserving surgery plus radiation therapy as long as the entire tumor can be removed during breast-conserving surgery. In breast-conserving surgery, doctors remove the tumor plus some surrounding normal tissue to reduce the risk that tissue that may contain cancer is left behind.

Before surgery, chemotherapy may be used to shrink the tumor before removing it. This approach sometimes enables some women to have breast-conserving surgery rather than mastectomy.

Breast-conserving surgery

Breast-conserving surgery leaves as much of the breast intact as possible (for cosmetic reasons). However, it is more important for doctors to be sure they remove the whole cancer than to risk leaving tissue that may contain cancer.

For breast-conserving surgery, doctors first determine how big the tumor is and how much tissue around it (called margins) needs to be removed. The size of the margins is based on how big the tumor is in relation to the breast. Then the tumor with its margins is surgically removed. Tissue from the margins is examined under a microscope to check for cancer cells that have spread outside the tumor. These findings help doctors decide on whether further treatment is needed. Various terms (for example, lumpectomy, wide excision, quadrantectomy) are used to describe how much breast tissue is removed.

Breast-conserving surgery is usually followed by radiation therapy.

The main advantage of breast-conserving surgery is cosmetic: This surgery may help preserve body image. Thus, when the tumor is large in relation to the breast, this type of surgery is less likely to be useful. In such cases, removing the tumor plus some surrounding normal tissue means removing most of the breast. Breast-conserving surgery is usually more appropriate when tumors are small. In about 15% of women who have breast-conserving surgery, the amount of tissue removed is so small that little difference can be seen between the treated and untreated breasts. However, in most women, the treated breast shrinks somewhat and may change in contour.

Mastectomy

Mastectomy is the other main surgical option. There are several types. In all types, all breast tissue is removed, but which other tissues and how much of them are left in place or removed vary by type:

  • Skin-sparing mastectomy leaves the muscle under the breast and enough skin to cover the wound. Reconstruction of the breast is much easier if these tissues are left. The lymph nodes in the armpit are not removed.

  • Nipple-sparing mastectomy is the same as skin-sparing mastectomy plus it leaves the nipple and the area of pigmented skin around the nipple (areola).

  • Simple mastectomy leaves the muscle under the breast (pectoral muscle) and the lymph nodes in the armpit.

  • Modified radical mastectomy consists of removing some lymph nodes in the armpit but leaves the muscle under the breast.

  • Radical mastectomy consists of removing the lymph nodes in the armpit and the muscle under the breast. This procedure is rarely done now unless the cancer has invaded the muscle under the breast.

Lymph node assessment

A network of lymphatic vessels and lymph nodes (lymphatic system) drain fluid from the tissue in the breast (and other areas of the body). Lymph nodes are designed to trap foreign or abnormal cells (such as bacteria or cancer cells) that may be contained in this fluid. Thus, breast cancer cells often end up in lymph nodes near the breast, such as those in the armpit. Usually, foreign and abnormal cells are then destroyed. However, the cancer cells sometimes continue to grow in the lymph nodes or pass through the nodes into the lymphatic vessels and spread to other parts of the body.

Doctors assess lymph nodes to determine whether cancer has spread to the lymph nodes in the armpit. If cancer is detected in these lymph nodes, it is more likely to have spread to other parts of the body. In such cases, different treatment may be needed.

Doctors first feel the armpit to check for enlarged lymph nodes. Depending on what doctors find, they may do one or more of the following:

  • Ultrasonography to check for lymph nodes that may be enlarged

  • A biopsy (by removing a lymph node or taking a sample of tissue with a needle using ultrasonography to guide placement of the needle)

  • Axillary lymph node dissection: Removal of many (typically 10 to 20) lymph nodes in the armpit

  • Sentinel lymph node dissection: Removal of only the lymph node or nodes that cancer cells are most likely to spread to

If doctors feel an enlarged lymph node in the armpit or are uncertain whether lymph nodes are enlarged, ultrasonography is done. If an enlarged lymph node is detected, a needle is inserted into it to remove a sample of tissue to be examined (fine-needle aspiration or core needle biopsy). Ultrasonography is used to guide placement of the needle.

If the biopsy detects cancer, axillary lymph node dissection is usually done. Removing many lymph nodes in the armpit, even if they contain cancer, does not help cure the cancer. However, it does help remove cancer from the armpit and helps doctors decide what treatment to use.

If the biopsy after ultrasonography does not detect cancer, a sentinel lymph node biopsy is done because even if there are no cancer cells in a biopsy sample, cancer cells may be present in other parts of a lymph node.

If doctors cannot feel any enlarged lymph nodes in the armpit, they do a sentinel lymph node biopsy as part of the operation to remove the cancer.

A sentinel lymph node biopsy is usually done instead of axillary lymph node dissection to assess the lymph nodes that otherwise appear normal. For a sentinel lymph node biopsy, doctors inject a blue dye and/or a radioactive substance into the breast near the tumor. These substances map the pathway from the breast to the first lymph node (or nodes) in the armpit. Doctors then make a small incision in the armpit, enabling them to see the area around the tumor. Doctors look for lymph nodes that look blue or give off a radioactive signal (detected by a handheld device). These lymph nodes are the ones that cancer cells are most likely to have spread to. These nodes are called sentinel lymph nodes because they are the first to warn that cancer has spread. Doctors remove these nodes and send them to a laboratory to be checked for cancer.

If the sentinel lymph nodes do not contain cancer cells, no other lymph nodes are removed.

If the sentinel nodes contain cancer, axillary lymph node dissection may be done, depending on various factors, such as

  • Whether a mastectomy is planned

  • How many sentinel nodes are present and whether the cancer has spread outside the nodes

Sometimes during surgery to remove the tumor, doctors discover that the cancer has spread to the lymph nodes, and axillary lymph node dissection is required. Before the surgery is done, women may be asked whether they are willing to let the surgeon do more extensive surgery if cancer has spread to the lymph nodes. Otherwise, a second surgical procedure, if needed, is done later.

Removal of lymph nodes often causes problems because it affects the drainage of fluids in tissues. As a result, fluids may accumulate, causing persistent swelling (lymphedema) of the arm or hand. Arm and shoulder movement may be limited. The more lymph nodes removed, the worse the swelling. Sentinel lymph node biopsy causes less lymphedema than axillary lymph node biopsy.

If lymphedema develops, it is treated by specially trained therapists. They teach women how to massage the area, which may help the accumulated fluid drain, and how to apply a bandage, which helps keep fluid from reaccumulating. The affected arm should be used as normally as possible, except that the unaffected arm should be used for heavy lifting. Women should exercise the affected arm daily as instructed and bandage it overnight indefinitely.

If lymph nodes have been removed, women may be advised to ask health care practitioners not to insert catheters or needles in veins in the affected arm and not to measure blood pressure in that arm. These procedures makes lymphedema more likely to develop or worsen. Women are also advised to wear gloves whenever they are doing work that may scratch or injure the skin of the hand and arm on the side of the surgery. Avoiding injuries and infections can help reduce the risk of developing lymphedema.

Other problems that may occur after lymph nodes are removed include temporary or persistent numbness, a persistent burning sensation, and infection.

What Is a Sentinel Lymph Node?

A network of lymphatic vessels and lymph nodes drain fluid from the tissue in the breast. The lymph nodes are designed to trap foreign or abnormal cells (such as bacteria or cancer cells) that may be contained in this fluid. Sometimes cancer cells pass through the nodes into the lymphatic vessels and spread to other parts of the body.

Although fluid from breast tissue eventually drains to many lymph nodes, the fluid usually drains first through one or only a few nearby lymph nodes. Such lymph nodes are called sentinel lymph nodes because they are the first to warn that cancer has spread.

What Is a Sentinel Lymph Node?

Breast reconstruction surgery

Breast reconstruction surgery may be done at the same time as a mastectomy or later.

Women and their doctor should consult with a plastic surgeon early during treatment to plan the breast reconstruction surgery. When reconstruction is done depends not only on the woman's preference but also on the other treatments needed. For example, if radiation therapy is done before reconstruction surgery, reconstruction options are limited.

Most often, the surgery is done by

  • Inserting an implant (made of silicone or saline)

  • Reconstructing the breast using tissue taken from other parts of the woman’s body

Surgeons often obtain tissue for breast reconstruction from a muscle in the lower abdomen. Alternatively, skin and fatty tissue (instead of muscle) from the lower abdomen can be used to reconstruct the breast.

Before inserting an implant, doctors use a tissue expander, which resembles a balloon, to stretch the remaining chest skin and muscle to make room for the breast implant. The tissue expander is placed under the chest muscle during mastectomy. The expander has a small valve that health care practitioners can access by inserting a needle through the skin. Over the next several weeks, a salt solution (saline) is periodically injected through the valve to expand the expander a little at a time. After expansion is complete, the expander is surgically removed, and the implant is inserted.

Alternatively, tissues taken from the woman's body (such as muscle and tissues under the skin) can be used for reconstruction. These tissues are taken from the abdomen, back, or buttock and moved to the chest area to create the shape of a breast.

The nipple and surrounding skin are usually reconstructed in a separate operation done later. Various techniques can be used. They include using tissue from the woman's body and tattooing.

Surgery may also be done to modify (augment, reduce, or lift) the other breast to make both breasts match.

Rebuilding a Breast

After a general surgeon removes a breast tumor and the surrounding breast tissue (mastectomy), a plastic surgeon may reconstruct the breast. A silicone or saline implant may be used. Or in a more complex operation, tissue may be taken from other parts of the woman’s body, such as the abdomen, buttock, or back.

Reconstruction may be done at the same time as the mastectomy—a choice that involves being under anesthesia for a longer time—or later—a choice that involves being under anesthesia a second time.

Reconstruction of the nipple and surrounding skin is done later, often in a doctor's office. A general anesthetic is not required.

In many women, a reconstructed breast looks more natural than one that has been treated with radiation therapy, especially if the tumor was large.

If a silicone or saline implant is used and enough skin was left to cover it, the sensation in the skin over the implant is relatively normal. However, neither type of implant feels like breast tissue to the touch. If skin from other parts of the body is used to cover the breast, much of the sensation is lost. However, tissue from other parts of the body feels more like breast tissue than does a silicone or saline implant.

Silicone occasionally leaks out of its sack. As a result, an implant can become hard, cause discomfort, and appear less attractive. Also, silicone sometimes enters the bloodstream.

Some women are concerned about whether the leaking silicone causes cancer in other parts of the body or rare diseases such as systemic lupus erythematosus (lupus). There is almost no evidence suggesting that silicone leakage has these serious effects, but because it might, the use of silicone implants has decreased, especially among women who have not had breast cancer.

Rebuilding a Breast

Preservation of Fertility

Women should not become pregnant while being treated for breast cancer.

If women wish to have children (preserve fertility) after being treated, they are referred to a reproductive endocrinologist before treatment is started. These women can then find out about procedures that may enable them to have children after treatment.

Options to preserve fertility include assisted reproductive techniques with ovarian stimulation and freezing eggs or embryos.

Choice of the procedure to be used to preserve fertility depends on the following:

  • Type of breast cancer

  • Type of breast cancer treatment that is planned

  • The woman's preferences

Assisted reproductive techniques may have side effects in women with estrogen receptor–positive cancer.

Removal of the Breast Without Cancer

Certain women with breast cancer have a high risk of developing breast cancer in their other breast (the one without cancer). Doctors may suggest that these women have that breast removed before cancer develops. This procedure is called contralateral (opposite side) prophylactic (preventive) mastectomy. This preventive surgery may be appropriate for women with any of the following:

  • A genetic mutation that increases the risk of developing breast cancer (BRCA1 or BRCA2)

  • At least two close, usually first-degree relatives who have had breast or ovarian cancer

  • Radiation therapy directed at the chest when women were under 30 years old

  • Lobular carcinoma in situ (a noninvasive type)

In women with lobular carcinoma in situ in one breast, invasive cancer is equally likely to develop in either breast. Thus, the only way to eliminate the risk of breast cancer for these women is to remove both breasts. Some women, particularly those who are at high risk of developing invasive breast cancer, choose this option.

Advantages of contralateral prophylactic mastectomy include the following:

  • Longer survival for women with breast cancer and a BRCA1 or BRCA2 mutation and possibly for women who are under 50 years old when they are diagnosed with breast cancer

  • Decreased need for cumbersome follow-up imaging tests after treatment

  • For some women, decreased anxiety

Disadvantages of this procedure include the following:

  • Twice the risk of complications

Instead of having a contralateral prophylactic mastectomy, some women may choose to have their doctor monitor the breast closely for cancer—for example with imaging tests.

Radiation Therapy

Radiation therapy is used to kill cancer cells at and near the site from which the tumor was removed, including nearby lymph nodes. Radiation therapy after breast-conserving surgery or mastectomy reduces the risk of cancer recurring near the site and in nearby lymph nodes. It improves the chances of survival for women who have large tumors or cancer that has spread to several nearby lymph nodes and may improve the chances of survival for other women.

Side effects of radiation therapy include swelling in the breast, reddening and blistering of the skin in the treated area, and fatigue. These effects usually disappear within several months, up to about 12 months. Fewer than 5% of women treated with radiation therapy have rib fractures that cause minor discomfort. In about 1% of women, the lungs become mildly inflamed 6 to 18 months after radiation therapy is completed. Inflammation causes a dry cough and shortness of breath during physical activity that last for up to about 6 weeks. Lymphedema may develop after radiation therapy.

To improve radiation therapy, doctors are studying several new procedures. Many of these procedures aim to target radiation to the cancer more precisely and spare the rest of the breast from the effects of radiation.

Drugs

Chemotherapy and hormone-blocking drugs can suppress the growth of cancer cells throughout the body.

For women with invasive breast cancer, chemotherapy or hormone-blocking drugs are usually begun soon after surgery. These drugs are continued for months or years. Some, such as tamoxifen, may be continued for 5 to 10 years. If tumors are larger than 5 centimeters (about 2 inches), chemotherapy or hormone-blocking drugs may be started before surgery. These drugs delay or prevent the recurrence of cancer in most women and prolong survival in some. However, some experts believe that these drugs are not necessary if the tumor is small and the lymph nodes are not affected, particularly in postmenopausal women, because the prognosis is already excellent.

Analyzing the genetic material of the cancer (predictive genomic testing) may help predict which cancers are susceptible to chemotherapy or hormone-blocking drugs.

Chemotherapy

Chemotherapy is used to kill rapidly multiplying cells or slow their multiplication. Chemotherapy alone cannot cure breast cancer. It must be used with surgery or radiation therapy. Chemotherapy drugs are usually given intravenously in cycles. Sometimes they are given by mouth. Typically, a day of treatment is followed by 2 or more weeks of recovery. Using several chemotherapy drugs together is more effective than using a single drug. The choice of drugs depends partly on whether cancer cells are detected in nearby lymph nodes.

Commonly used drugs include cyclophosphamide, doxorubicin, epirubicin, 5-fluorouracil, methotrexate, and paclitaxel (see Chemotherapy).

Side effects (such as vomiting, nausea, hair loss, and fatigue) vary depending on which drugs are used. Chemotherapy can cause infertility and early menopause by destroying the eggs in the ovaries. Chemotherapy may also suppress the production of blood cells by the bone marrow and thus cause anemia or bleeding or increase the risk of infections. So drugs, such as filgrastim or pegfilgrastim, may by used to stimulate the bone marrow to produce blood cells.

Hormone-blocking drugs

Hormone-blocking drugs interfere with the actions of estrogen or progesterone, which stimulate the growth of cancer cells that have estrogen and/or progesterone receptors. Hormone-blocking drugs may be used when cancer cells have these receptors, sometimes instead of chemotherapy. The benefits of hormone-blocking drugs are greatest when cancer cells have both estrogen and progesterone receptors.

Hormone-blocking drugs include

  • Tamoxifen: Tamoxifen, given by mouth, is a selective estrogen-receptor modulator. It binds with estrogen receptors and inhibits growth of breast tissue. In women who have estrogen receptor–positive cancer, tamoxifen, taken for 5 years, increases the likelihood of survival by about 25%, and 10 years of treatment may be even more effective. Tamoxifen, which is related to estrogen, has some of the benefits and risks of estrogen therapy taken after menopause. For example, it may decrease the risk of osteoporosis and fractures. It increases the risk of blood clots in the legs and lungs. It also increases the risk of developing cancer of the uterus (endometrial cancer). Thus, if women taking tamoxifen have spotting or bleeding from the vagina, they should see their doctor. However, the improvement in survival after breast cancer far outweighs the risk of endometrial cancer. Tamoxifen, unlike estrogen therapy, may worsen the vaginal dryness or hot flashes that occur after menopause.

  • Aromatase inhibitors: These drugs (anastrozole, exemestane, and letrozole) inhibit aromatase (an enzyme that converts some hormones to estrogen) and thus reduce the production of estrogen. In postmenopausal women, these drugs may be more effective than tamoxifen. Aromatase inhibitors may be given instead of tamoxifen or after tamoxifen treatment has been completed. Aromatase inhibitors may increase the risk of osteoporosis.

Monoclonal antibodies

Monoclonal antibodies are synthetic copies (or slightly modified versions) of natural substances that are part of the body’s immune system. These drugs enhance the immune system’s ability to fight cancer.

Trastuzumab and pertuzumab are a type of monoclonal antibody called anti-HER2 drugs. They are used with chemotherapy to treat metastatic breast cancer only when the cancer cells have too many HER2 receptors. These drugs bind with HER2 receptors and thus help prevent cancer cells from multiplying. Sometimes both of these drugs are used. Trastuzumab is usually taken for a year. Both drugs can weaken the heart muscle. So doctors monitor heart function during treatment.

Treatment of Noninvasive Cancer (Stage 0)

For ductal carcinoma in situ, treatment usually consists of one the following:

  • A mastectomy

  • Removal of the tumor and a large amount of surrounding normal tissue (wide excision) with or without radiation therapy

Some women with ductal carcinoma in situ are also given hormone-blocking drugs as part of their treatment.

For lobular carcinoma in situ, treatment includes the following:

  • Classic lobular carcinoma in situ: Surgical removal to check for cancer and, if no cancer is detected, close observation afterward and sometimes tamoxifen, raloxifene, or an aromatase inhibitor to reduce the risk of developing invasive cancer

  • Pleomorphic lobular carcinoma in situ: Surgery to remove the abnormal area and sometimes tamoxifen or raloxifene to reduce the risk of developing invasive cancer

Observation consists of a physical examination every 6 to 12 months for 5 years and once a year thereafter plus mammography once a year. Although invasive breast cancer may develop, the invasive cancers that develop are usually not fast growing and can usually be treated effectively. Furthermore, because invasive cancer is equally likely to develop in either breast, the only way to eliminate the risk of breast cancer for women with lobular carcinoma in situ is removal of both breasts (bilateral mastectomy). Some women, particularly those who are at high risk of developing invasive breast cancer, choose this option.

Women with lobular carcinoma in situ are often given tamoxifen, a hormone-blocking drug, for 5 years. It reduces but does not eliminate the risk of developing invasive cancer. Postmenopausal women may be given raloxifene or sometimes an aromatase inhibitor instead.

Treatment of Localized or Regional Invasive Cancer (Stages I Through III)

For cancers that have not spread beyond nearby lymph nodes, treatment almost always includes surgery to remove as much of the tumor as possible. Also, one of the following is done to help stage the cancer.

  • Axillary lymph node dissection (removal of many lymph nodes from the armpit)

  • A sentinel lymph node biopsy (removal of the lymph node or the first few nodes that are nearest the breast)

A mastectomy or breast-conserving surgery is commonly used to treat invasive cancer that has spread extensively within the milk ducts (invasive ductal carcinoma). Breast-conserving surgery is used only when the tumor is not too large because the entire tumor plus some of the surrounding normal tissue must be removed. If the tumor is large, removing the tumor plus some surrounding normal tissue essentially results in removing most of the breast. The initial surgery may include axillary lymph node surgery and is usually followed by radiation therapy.

Sometimes, when the tumor is too large for breast-conserving surgery, chemotherapy is given before surgery to reduce the size of the tumor. If chemotherapy reduces the size of the tumor enough, breast-conserving surgery may be possible.

Whether radiation therapy, chemotherapy, or both are used after surgery depends on many factors, such as the following:

  • How large the tumor is

  • Whether menopause has occurred

  • Whether the tumor has receptors for hormones

  • How many lymph nodes contain cancer cells

After surgery and radiation therapy, chemotherapy is usually given. If the cancer has estrogen receptors, women who are still menstruating are usually given tamoxifen, and postmenopausal women are given an aromatase inhibitor.

Treatment of Cancer That Has Spread (Stage IV)

Breast cancer that has spread beyond the lymph nodes is rarely cured, but most women who have it live at least 2 years, and a few live 10 to 20 years. Treatment extends life only slightly but may relieve symptoms and improve quality of life. However, some treatments have troublesome side effects. Thus, deciding whether to be treated and, if so, which treatment to choose can be highly personal.

Choice of therapy depends on the following:

  • Whether the cancer has estrogen and progesterone receptors

  • How long the cancer had been in remission before it spread

  • How many organs and how many parts of the body the cancer has spread to (where the metastases are)

  • Whether the woman is postmenopausal or still menstruating

Most women are treated with chemotherapy or hormone-blocking drugs. However, chemotherapy, especially regimens that have uncomfortable side effects, is often postponed until symptoms (pain or other discomfort) develop or the cancer starts to worsen quickly. Pain is usually treated with analgesics. Other drugs may be given to relieve other symptoms. Chemotherapy or hormone-blocking drugs are given to relieve symptoms and improve quality of life rather than to prolong life.

The most effective chemotherapy regimens for breast cancer that has spread include capecitabine, docetaxel, doxorubicin, gemcitabine, paclitaxel, and vinorelbine.

Hormone-blocking drugs are preferred to chemotherapy in certain situations. For example, these drugs may be preferred when the cancer is estrogen receptor–positive, when cancer has not recurred for more than 2 years after diagnosis and initial treatment, or when cancer is not immediately life threatening. Different hormone-blocking drugs are used in different situations:

  • Tamoxifen: For women who are still menstruating, tamoxifen is usually the first hormone-blocking drug used.

  • Aromatase inhibitors: For postmenopausal women who have estrogen receptor–positive breast cancer, aromatase inhibitors (such as anastrozole, letrozole, and exemestane) may be more effective as a first treatment than tamoxifen.

  • Progestins: These drugs, such as medroxyprogesterone or megestrol, may be used after aromatase inhibitors and tamoxifen when these drugs are no longer effective.

  • Fulvestrant: This drug may be used when tamoxifen is no longer effective. It destroys the estrogen receptors in cancer cells.

Alternatively, for women who are still menstruating, surgery to remove the ovaries, radiation to destroy them, or drugs to inhibit their activity (such as buserelin, goserelin, or leuprolide) may be used to stop estrogen production. These therapies may be used with tamoxifen.

Trastuzumab (a type of monoclonal antibody called an anti-HER2 drug) can be used to treat cancers that have too many HER2 receptors and that have spread throughout the body. Trastuzumab can be used alone or with chemotherapy drugs (such as paclitaxel), with hormone-blocking drugs, or with pertuzumab (another anti-HER2 drug). Trastuzumab plus chemotherapy plus pertuzumab slows the growth of breast cancers that have too many HER2 receptors and increases survival time more than trastuzumab plus chemotherapy. Trastuzumab can also be used with hormone-blocking drugs to treat women who have estrogen receptor–positive breast cancer.

Tyrosine kinase inhibitors (such as lapatinib and neratinib), another type of anti-HER drug, block the activity of HER2. These drugs are being increasingly used in women with cancers that have too many HER2 receptors.

In some situations, radiation therapy may be used instead of or before drugs. For example, if only one area of cancer is detected and that area is in a bone, radiation to that bone might be the only treatment used. Radiation therapy is usually the most effective treatment for cancer that has spread to bone, sometimes keeping it in check for years. It is also often the most effective treatment for cancer that has spread to the brain.

Surgery may be done to remove single tumors in other parts of the body (such as the brain) because such surgery can relieve symptoms. Mastectomy (removing the breast) may be done to help relieve symptoms. But it is unclear whether removing the breast helps prolong life when cancer has spread to other parts of the body and has been treated and controlled.

Bisphosphonates (used to treat osteoporosis), such as pamidronate or zoledronate, reduce bone pain and bone loss and may prevent or delay bone problems that can result when cancer spreads to bone.

Table
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Treating Breast Cancer Based on Type

Type

Possible Treatments

Ductal carcinoma in situ (cancer confined to the milk ducts of the breast)

Mastectomy

Sometimes breast-conserving surgery (removal of the tumor, leaving as much of the breast intact as possible) with or without radiation therapy

Sometimes hormone-blocking drugs

Lobular carcinoma in situ, classic (cancer confined to the milk-producing glands of the breast)

Sometimes surgery to check for cancer

If no cancer is detected, observation plus regular examinations and mammograms

Tamoxifen or, for some postmenopausal women, raloxifene or an aromatase inhibitor (such as anastrozole, exemestane, or letrozole) to reduce the risk of invasive cancer

Rarely, bilateral mastectomy (removal of both breasts) to prevent invasive cancers

Lobular carcinoma in situ, pleomorphic (which, unlike the classic type, leads to invasive cancer)

Surgery to remove the abnormal area and some of the tissue around it

Sometimes tamoxifen or raloxifene to try to prevent cancer from developing

Stages I and II (early-stage) cancer

Chemotherapy before surgery if the tumor is larger than 5 centimeters (about 2 inches) or is stuck to the chest wall to increase the chances of being able to do breast-conserving surgery

Breast-conserving surgery to remove the tumor and some surrounding tissue, followed by radiation therapy

Mastectomy with or without breast reconstruction

After surgery, chemotherapy, hormone-blocking drugs, anti-HER2 drugs (such as trastuzumab), or a combination, except in some postmenopausal women with tumors smaller than 0.5 to 1.0 centimeter (about 0.2 to 0.4 inches) and no cancer in the lymph nodes

Stage III (locally advanced) cancer (including inflammatory breast cancer)

Chemotherapy or sometimes hormone-blocking drugs before surgery to reduce the tumor’s size

Breast-conserving surgery or mastectomy if the tumor is small enough to be completely removed

Usually, radiation therapy after surgery

Sometimes chemotherapy, hormone-blocking drugs, or both after surgery

For inflammatory breast cancer, mastectomy, chemotherapy, and radiation therapy

Stage IV (metastatic) cancer

If cancer causes symptoms and occurs in several sites, hormone-blocking drugs, ovarian ablation therapy,* or chemotherapy

If the cancer cells have too many HER2 receptors, trastuzumab, sometimes with pertuzumab

Radiation therapy for the following:

  • Metastases to the brain

  • Metastases that recur in the skin

  • Metastases that occur in one area of bone and that cause symptoms

For metastases to bone, bisphosphonates (such as zoledronate or pamidronate) given intravenously to reduce bone pain and bone loss

Paget disease of the nipple

If breast cancer is also present, treatment based on that type of breast cancer

Occasionally, surgical removal of only the nipple with some surrounding normal tissue (local excision)

Breast cancer that recurs in the breast or nearby structures

Mastectomy sometimes preceded by chemotherapy or hormone-blocking drugs

Sometimes radiation therapy

Chemotherapy or hormone therapy

Phyllodes tumors

Removal of the tumor and surrounding normal tissue (wide excision)

Radiation therapy if the tumor is cancerous

Mastectomy if the tumor is large or if analysis of the abnormal cells suggests cancer

* Ovarian ablation therapy involves removing the ovaries or using drugs to suppress estrogen production by the ovaries. The ovaries are the main source of estrogen in premenopausal women.

Treatment of Specific Types of Breast Cancer

For inflammatory breast cancer, treatment usually consists of both chemotherapy and radiation therapy. Mastectomy is usually done.

For Paget disease of the nipple, treatment is usually similar to that of other types of breast cancer. It often involves simple mastectomy or breast-conserving surgery plus removal of the lymph nodes. Breast-conserving surgery is usually followed by radiation therapy. Less commonly, only the nipple with some surrounding normal tissue is removed. If another breast cancer is also present, treatment is based on that type of breast cancer.

For phyllodes tumors (whether cancerous or not), treatment usually consists of removing the tumor and a large amount of surrounding normal tissue (wide excision). If the tumor is large in relation to the breast, a simple mastectomy may be done. After surgical removal, about 20 to 35% of tumors recur near the same site. About 10 to 20% of tumors metastasize to distant sites. If the tumor is cancerous, radiation therapy is used.

Follow-up Care

After treatment is completed, follow-up physical examinations, including examination of the breasts, chest, neck, and armpits, are done every 3 months for 2 years, then every 6 months for 5 years from the date the cancer was diagnosed. Regular mammograms and breast self-examinations are also important. Women should promptly report certain symptoms to their doctor:

  • Any changes in their breasts

  • Pain

  • Loss of appetite or weight

  • Changes in menstruation

  • Bleeding from the vagina (if not associated with menstrual periods)

  • Blurred vision

  • Any symptoms that seem unusual or that persist

Diagnostic procedures, such as chest x-rays, blood tests, bone scans, and computed tomography (CT), are not needed unless symptoms suggest the cancer has recurred.

The effects of treatment for breast cancer cause many changes in a woman’s life. Support from family members and friends can help, as can support groups. Counseling may be helpful.

End-of-Life Issues

For women with metastatic breast cancer, quality of life may deteriorate, and the chances that further treatment will prolong life may be small. Staying comfortable may eventually become more important than trying to prolong life.

Cancer pain can be adequately controlled with appropriate drugs. So if women are having pain, they should ask their doctor for treatment to relieve it. Treatments can also relieve other troublesome symptoms, such as constipation, difficulty breathing, and nausea.

Psychologic and spiritual counseling may also help.

Women with metastatic breast cancer should prepare advance directives indicating the type of care they desire in case they are no longer able to make such decisions. Also, making or updating a will is important.

Drugs Mentioned In This Article

Generic Name Select Brand Names
PROVERA
CYTOXAN (LYOPHILIZED)
NEULASTA
CARAC
CRINONE
XELODA
OTREXUP
AREDIA
GEMZAR
NAVELBINE
FASLODEX
HERCEPTIN
ARIMIDEX
EVISTA
NEUPOGEN
PERJETA
AROMASIN
LUPRON
TAXOL
ELLENCE
MEGACE
TYKERB
No US brand name
TAXOTERE
FEMARA
ZOLADEX
NOLVADEX
Neratinib
NOTE: This is the Consumer Version. DOCTORS: Click here for the Professional Version
Click here for the Professional Version
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