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Breast Cancer


The Manual's Editorial Staff

Reviewed/Revised Oct 2023
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Cancer is when cells grow abnormally. Cancer cells don't look or work like normal cells and keep multiplying out of control. Cancer cells can invade and destroy nearby healthy tissue. Sometimes, cancer cells travel to distant parts of the body and grow there. Cancer that has traveled to another part of the body is called metastatic cancer. Cancer can develop from any tissue in your body.

The Breasts

What is breast cancer?

Breast cancer is when cells in your breast become cancerous. Breast cancer often happens in the glands that make breast milk or in the milk ducts (tubes that carry milk from your milk-making glands to your nipples).

What causes breast cancer?

Doctors don't know exactly why some women get breast cancer. However, there are several risk factors. You have a higher chance of having breast cancer if:

  • You have the BRCA1 or BRCA2 gene, which cause breast cancer

  • You're older than 50

  • You've already had breast cancer before

  • Your mother, sister, or daughter had breast cancer

Women without these risk factors can also get breast cancer.

What are the symptoms of breast cancer?

The first symptom is usually:

  • A painless lump in your breast

If your cancer has grown:

  • The lump is bigger and may feel hard and stuck in place

  • The skin over the lump may be warm, red, and swollen

  • The skin over the lump may look dimpled and leathery like the skin of an orange

If the breast cancer has spread to other parts of your body, the first sign may be a problem in that body part, like trouble breathing or an achy or weak bone.

How can doctors tell if I have breast cancer?

If you don't have symptoms

Because breast cancer is common, doctors do tests for breast cancer in women who don't have any symptoms. These are called screening tests.

All women should be screened for breast cancer. For most women, doctors start screening at age 40 or 50. Screening tests are done every year or 2 until about age 75.

Breast cancer screening tests include:

A mammogram is a special x-ray of your breasts. Doctors use it to check for abnormal spots inside breasts. Here’s how a mammogram works:

  • You’ll take off your shirt and bra and put on a robe that opens in the front

  • A technician will place your breast on top of an x-ray plate

  • A plastic cover will press down on your breast, making it as flat as it can be

  • The technician will take x-rays of your breast from the top

  • The technician may turn the x-ray plate and plastic cover to get a side view of your breast

Mammograms are one of the best ways to find breast cancer early. But not all the spots they find are breast cancer. You will need other tests to determine if an abnormal spot is breast cancer. Talk to your doctor about when to start getting mammograms based on your age and your health.

Mammography: Screening for Breast Cancer

Mammography: Screening for Breast Cancer

A breast exam is part of a regular physical exam. During a breast exam, doctors feel each breast with their fingers to try to find lumps. They’ll also check for enlarged lymph nodes in your armpits and above your collarbone.

An MRI can be done if you have a high risk of getting breast cancer. An MRI is a test that uses a strong magnetic field to create a detailed picture of the inside of your body.

If you have symptoms

If you have a breast lump or other symptoms of breast cancer, doctors do tests to check for breast cancer:

Depending on your symptoms and the results of these tests, your doctor may:

  • Put a needle in the lump and take out fluid or a sample of tissue

  • Make a cut in the skin to take out part of the lump and look at it under a microscope (biopsy)

After breast cancer is diagnosed

If the biopsy finds cancer cells, doctors do tests to see whether your cancer will respond to hormone treatment. For example, doctors test the cancer for estrogen, progesterone, and HER2 receptors.

Doctors also do tests to see whether the cancer has spread. Tests usually include:

  • Blood tests

  • Chest x-ray

  • Sometimes a bone scan, or a CT (computed tomography) scan of your belly

Breast cancer stages

The stage describes how far along the cancer is. Stages are numbered 0 through 4 and given a letter A through C. The lower your cancer's stage number and letter, the more likely you are to survive.

To figure out the stage, doctors consider:

  • The size of the cancer

  • Whether it has spread to nearby areas, such as the lymph nodes in the armpit

  • If the cancer has spread to distant parts of the body, such as the lungs or bones

How do doctors treat breast cancer?

Doctors treat breast cancer based on what type and how far along it is. There are several types of treatment for breast cancer. You and your doctor will decide what types of treatment to do.


There are 2 main types of surgery for breast cancer:

  • Breast-conserving surgery removes just the cancer and leaves the rest of your breast

  • Mastectomy removes all of your breast and sometimes lymph nodes in your armpit

Some mastectomies leave behind some breast skin or your nipple. This makes it easier to do breast reconstruction surgery.

Losing some or all of a breast can be very upsetting. But the most important thing is to remove all of the cancer, rather than leave behind breast tissue that may contain cancer.

If you need to have a breast removed, you may be able to get reconstruction surgery done at the same time or later. There are 2 types of breast reconstruction surgery:

  • Doctors can insert an implant made of silicone or saline

  • Doctors can rebuild your breast using tissue from other parts of your body, such as your belly, back, or bottom

Radiation therapy

  • Doctors often give radiation therapy after surgery to lessen the chance of cancer coming back

  • If the cancer comes back in the breast area after surgery, you may get more radiation therapy

Radiation therapy can make your skin red and blistered, and you may feel tired all over.


  • Doctors often give chemotherapy before surgery to shrink the cancer and make it easier to remove completely

  • You may also get chemotherapy after surgery or if your cancer has spread

Chemotherapy medicines can cause you to lose your hair, throw up, feel sick to your stomach, or feel tired all over. You may also have trouble getting pregnant or stop having periods.

Hormone-blocking medicines

  • Some breast cancer cells are stimulated to grow by estrogen and progesterone, which are natural female hormones

  • Hormone-blocking medicines block these hormones so they don't make your tumor grow

  • Tamoxifen is a common medicine given to block the hormone estrogen

  • Doctors sometimes use hormone-blocking medicine rather than chemotherapy

After breast cancer treatment

You'll see your doctor regularly. At these visits, doctors will check your breasts, chest, neck, and armpits to see if the cancer has come back.

Pay attention to how your breasts look and feel and tell your doctor if you notice any changes or have any of these symptoms:

  • Pain

  • Losing weight or not feeling hungry

  • Changes in your monthly periods

  • Bleeding from your vagina that isn’t part of your monthly periods

  • Blurry vision

  • Any other symptoms that seem unusual or don’t go away

If you’re having a hard time after your treatment, consider joining a support group or talking to a counselor.

What if treatment doesn't work?

If you have very severe breast cancer, you may choose to focus on feeling better rather than trying to live longer. Doctors can help treat your symptoms.

A counselor or faith leader may also help you cope with your emotions.

If you don’t have them yet, set up a will and a legal document that tells what kind of care you want if you can’t tell your doctors on your own. The document is called an advance directive Advance Directives Health care advance directives are legal documents that communicate a person’s wishes about health care decisions in the event the person becomes incapable of making health care decisions. There... read more .

Drugs Mentioned In This Article

Generic Name Select Brand Names
Nolvadex, Soltamox
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