|
Among men in the United States, prostate cancer is the most common cancer and one of the most common causes of cancer death. The chance of developing prostate cancer increases with age and is greater for
Prostate cancer usually grows very slowly and may take decades to produce symptoms. Thus, particularly because it occurs more often in older men, far more men have prostate cancer than die from it. Many men with prostate cancer die from other causes without ever knowing that the cancer was present.
Prostate cancer begins as a small bump in the gland. Most prostate cancers grow very slowly and never cause symptoms. Some, however, grow rapidly or spread outside the prostate. The cause of prostate cancer is not known.
Symptoms
Prostate cancer usually causes no symptoms until it reaches an advanced stage. Sometimes, symptoms similar to those of benign prostatic hyperplasia (BPH) develop, including difficulty urinating and a need to urinate frequently or urgently. However, these symptoms do not develop until after the cancer grows large enough to compress the urethra and partially block the flow of urine. Later, prostate cancer may cause bloody urine or a sudden inability to urinate.
In some men, symptoms of prostate cancer develop only after it spreads (metastasizes). The areas most often affected by cancer spread are bone (typically the pelvis, ribs, or vertebrae) and the kidneys. Bone cancer tends to be painful and may weaken the bone enough for it to easily fracture. Prostate cancer can also spread to the brain, which eventually causes seizures, confusion, headaches, weakness, or other neurologic symptoms. Spread to the spinal cord, which is also common, can cause pain, numbness, weakness, or urinary incontinence. After the cancer spreads, anemia is common.
Diagnosis
Doctors may suspect prostate cancer based on the symptoms, the results of a digital rectal examination, or the results of screening blood tests. The screening blood test is a measurement of prostate-specific antigen (PSA) levels. PSA is a substance produced only by prostate gland tissue.
If results of these tests suggest cancer, ultrasound scanning is usually done. In men with prostate cancer, ultrasound scans may or may not reveal the cancer but are used to guide biopsy of the prostate.
If the results of a digital rectal examination or PSA test suggest prostate cancer, tissue samples from the prostate are taken and analyzed (biopsy). When doing a biopsy, doctors usually first obtain images of the prostate by inserting an ultrasound probe (transducer) into the rectum (transrectal ultrasound). Doctors then insert a needle through the probe and use the needle to obtain tissue samples several times. Usually, 5 or 6 samples are taken from each side of the prostate to increase the likelihood of finding a small cancer. This procedure takes only a few minutes, and men are given local anesthesia.
Grading and staging help doctors determine the likely course and the best treatment of the cancer.
Grading:
The Gleason scoring system is the most common way to grade prostate cancer. Based on the microscopic examination of tissues obtained from the biopsy, a number between 1 and 5 is assigned based on how distorted the cells appear. Because cancer cells often vary in their appearance, the number score for the most common abnormal cells is added to the number for the next most common abnormal cells to give a total score from 2 to 10. Scores between 6 and 7 are most common. The higher the number (high grade), the more aggressive the cancer is and the more likely it is that the cancer will spread.
Staging:
Prostate cancers are staged according to three criteria:
Testing to stage the cancer is often done when cancer is diagnosed. However, such testing may not be necessary when the likelihood of spread beyond the prostate is extremely low. Likelihood of spread is low when cancers have a Gleason score of 7 or less, the PSA level is less than 10 ng/mL, and the cancer has not penetrated the surface of the gland. Results of the digital rectal examination, ultrasound scan, and biopsy reveal how far the cancer has spread within the prostate.
If likelihood of spread is not low, doctors usually do a computed tomography (CT) scan or magnetic resonance imaging (MRI) of the abdomen and pelvis. Sometimes the MRI is done using a special coil inserted in the rectum. A bone scan may be done in people who have pain in their bones or who have a very high PSA level.
If spread to the brain or spinal cord is suspected, CT or MRI of those organs is done.
Screening:
Because prostate cancer is common, many doctors check for it in men with no symptoms (screening). However, because screening tests are positive in many men who do not have cancer and because some men who do have cancer may not require treatment, experts disagree about whether and when screening is helpful. Screening is considered in men older than 50 and in those older than 40 who have risk factors, such as being black or having a family history of prostate cancer. Benefits of screening may decrease with age. For example, one professional organization recommends against screening men who are older than 75 or who are not expected to live at least 10 more years. Screening, once begun, is usually repeated yearly.
To screen for prostate cancer, doctors do a digital rectal examination and a blood test to measure PSA levels. If the prostate gland is hard, irregularly enlarged, or has a lump or if the PSA level is elevated, prostate cancer is more likely. However, PSA levels can be misleading. The PSA level can be normal when prostate cancer is present and can be elevated for reasons other than prostate cancer. PSA levels normally increase with age and with disorders such as BPH and prostatitis. Men with an elevated PSA level then require a transrectal prostate biopsy to identify those who have cancer. Because most men who have elevated PSA levels on screening tests do not have prostate cancer, many biopsies have negative results.
Some prostate cancers are aggressive and potentially fatal but may not cause symptoms until they are too advanced to be cured. Screening offers the advantage of finding such cancers early—when they might be cured. However, because many prostate cancers grow slowly and often never cause symptoms or death, screening may find cancers that would probably not hurt or kill a man even if they were never detected. The side effects of treating such a cancer can be more damaging than leaving the cancer untreated. Thus, it is not clear whether the benefits of screening outweigh the discomfort, stress, and possible harm from unnecessary testing and treatment.
Prognosis
Prognosis for most men with prostate cancer is very good. Most elderly men with prostate cancer tend to live as long as other men their age who have similar general health and do not have prostate cancer. For many men, long-term remission or even cure is possible. The prognosis depends upon the cancer's grade and stage. High-grade cancers have a poor prognosis unless treated very early. Cancers that have spread to surrounding tissues also have a poorer prognosis. Metastatic prostate cancer has no cure. Most men with metastatic cancer live about 1 to 3 years after diagnosis, but some live for many years.
Treatment
Choosing among treatment options can be complicated. Because studies have not directly compared one treatment to another, doctors are uncertain which treatment is most effective. Furthermore, for some men, doctors are not sure whether treatment will prolong life. Such men include those who are not expected to live very long (either because of old age or serious health problems) and those with low PSA levels who have low-grade cancers confined to the prostate. Thus, men often make their decision by balancing their degree of discomfort in living with a cancer that might or might not harm them against the possible side effects of treatment. Surgery, radiation therapy, and hormonal therapy may cause incontinence, erectile dysfunction (impotence), or other problems. For these reasons, men's preferences are a bigger consideration in choosing treatment for prostate cancer than they are for many other disorders.
Treatment for prostate cancer usually involves one of three strategies:
Active surveillance (formerly called watchful waiting) means doctors give no treatment unless the cancer progresses. The advantage of this strategy is avoiding or postponing the potential side effects of treatment. Active surveillance should be considered mainly by elderly men (perhaps those over 70) whose cancers are unlikely to spread or cause symptoms. For example, most cancers that are confined to a small area within the prostate and have low Gleason scores grow very slowly and usually do not spread for many years. Thus, older men, particularly those who have other serious health problems, are far more likely to die of other causes before such cancers kill them or cause symptoms. In younger men, particularly those who are healthy, even a slow-growing cancer may eventually cause symptoms. In such men, active surveillance may be less preferred. During active surveillance, doctors periodically ask about symptoms, measure the PSA level, and do digital rectal examinations to determine whether the cancer is causing symptoms, growing rapidly, or spreading. Younger men may also have periodic repeat biopsies. If testing shows growth or spread, doctors offer curative or palliative treatment.
Curative treatment aims to remove all of the cancer and includes
Curative (also called definitive) treatment is a common strategy for men with cancers confined to the prostate that are likely to cause troublesome symptoms or death. Such cancers include those that are growing rapidly as well as some small, slowly growing cancers in men who are likely to live for some time (perhaps at least 10 or 15 years). Such men are typically those who are healthy, younger (particularly those under 60), or both. Curative treatment is not pursued if cancer has spread widely, but it can benefit some men with cancers that have spread to the area just outside the prostate. Such cancers are likely to cause symptoms within a relatively short period. However, curative treatment is most likely to be successful with cancers that are still confined to the area near the prostate. Curative treatment can prolong life and reduce or eliminate severe symptoms resulting from some cancers. However, some men experience side effects of curative treatment, most significantly erectile dysfunction and incontinence, which can impair quality of life.
Palliative treatment aims to treat the symptoms rather than cure the cancer. Palliative therapies include
Palliative treatment is best suited to men with widespread prostate cancer, which is not curable. The growth or spread of such cancers can usually be slowed or temporarily reversed, relieving symptoms. Besides trying to slow the cancer's growth and spread, doctors may try to relieve symptoms resulting from the effects of cancer in other organs and tissues (such as the bones). However, because these treatments cannot cure the cancer, symptoms eventually worsen. Death from the disease eventually follows.
Surgery:
Surgically removing the prostate (prostatectomy) is useful for cancer that is confined to the prostate. Prostatectomy is not done if staging tests show the cancer has spread. Prostatectomy is very effective in curing low-grade, slowly-growing cancers but is less effective in high-grade, fast-growing cancers. Such cancers are more likely to have spread even if spread is not detectable with staging tests at the time of diagnosis.
Prostatectomy requires general or spinal anesthesia, an overnight hospital stay, and a surgical incision. Following surgery, men must have a catheter in their penis for a week or two until the connection between the bladder and urethra heals. Doctors do not routinely give radiation therapy, chemotherapy, or hormone therapy before or after surgery, but studies are being done to determine whether such treatments may benefit certain men.
Prostatectomy may lead to permanent erectile dysfunction and urinary incontinence. Erectile dysfunction may occur because the nerves to the penis that control erection run across the prostate and may be damaged during surgery. Incontinence may occur because part of the sphincter that closes the opening at the bottom of the bladder must be removed during surgery.
Techniques for doing prostatectomy include open radical prostatectomy and laparoscopic or robotic radical prostatectomy.
In open radical prostatectomy, the entire prostate, the seminal vesicles, and part of the vas deferens are removed through an incision in the lower abdomen or, rarely, in the area between the scrotum and anus. In the laparoscopic and robotic-assisted laparoscopic procedures, the same structures are removed, but these procedures are done through smaller incisions and result in less postoperative pain and blood loss.
Radical prostatectomy, irrespective of technique, is the surgery done when trying to cure prostate cancer. However, the procedure causes incontinence in about 3% of men and partial incontinence in more. Temporary incontinence develops in most men and may last for several months. Incontinence is less likely in younger men. A degree of erectile dysfunction commonly develops after radical prostatectomy and is more common in older men. Blockage of urine flow caused by narrowing of part of the bladder or scarring of the urethra (urethral stricture) develops in 7 to 20% of men. More than 90% of men with cancer confined to the prostate live at least 10 years after radical prostatectomy. Younger men who can otherwise expect to live at least 10 to 15 more years are most likely to benefit from radical prostatectomy. Usually prostatectomy can be done in such a way that some of the nerves needed to achieve erection are spared—this procedure is called nerve-sparing radical prostatectomy. This procedure cannot be used to treat cancer that has invaded the nerves and blood vessels of the prostate. Nerve-sparing radical prostatectomy is less likely than non–nerve-sparing radical prostatectomy to cause erectile dysfunction. Most men are diagnosed early and, thus, can be treated with nerve-sparing radical prostatectomy.
Radiation Therapy:
Radiation therapy (see Prevention and Treatment of Cancer: Radiation Therapy) may cure cancers that are confined to the prostate, as well as cancers that have invaded tissues around the prostate. Although radiation therapy cannot cure cancer that has spread to distant organs, it can help relieve the pain resulting from the spread of prostate cancer to bone. Combining radiation therapy and surgery does not seem to work better than either alone.
For many stages of prostate cancer, 10-year survival rates with radiation therapy are nearly as high as those achieved with surgery. More than 90% of men with cancer confined to the prostate live at least 10 years after undergoing radiation therapy. Radiation therapy can be delivered as
External beam radiation therapy uses a machine to send beams of radiation to the prostate and surrounding tissues. CT is often used to help focus the radiation beams more precisely on the cancer by precisely identifying the structures affected. This approach is called three-dimensional conformal radiation therapy. Treatments are usually given 5 days per week for 7 to 8 weeks. Although some degree of erectile dysfunction can occur in up to 40% of men, it is less likely to develop after radiation therapy than after prostatectomy. Incontinence is rare when three-dimensional conformal radiation therapy is used. Scars that narrow the urethra and impede the flow of urine (urethral strictures) develop in about 7% of men. Other troublesome but usually temporary side effects of external beam radiation therapy include burning during urination, having to urinate frequently, blood in the urine, diarrhea that is sometimes bloody, irritation of the rectum and diarrhea (radiation proctitis), and sudden urges to defecate. Other forms of external beam radiation therapy that are newer and may have fewer side effects include proton beam therapy and intensity modulated radiation therapy (IMRT).
Radioactive implants can be inserted into the prostate (brachytherapy). The implants are small, seedlike pieces of radioactive material. Doctors inject the implants into the prostate gland through the area between the scrotum and anus using guidance from ultrasound or CT scans. Brachytherapy can be done in less than 2 hours, does not require repeated treatment sessions, and uses only spinal anesthesia. Brachytherapy also can deliver high doses of radiation to the prostate while often sparing healthy surrounding tissues and producing fewer side effects. However, brachytherapy may cause urethral strictures in up to 10% of men. (Seeds may later be passed in the urine. They are radioactive, so they should be kept away from pregnant women, because the fetus may be susceptible to radiation-induced birth defects. The seeds can set off Homeland Security radiation detectors.) Cure rates 10 to 15 years after brachytherapy are similar to rates obtained with other treatments for some men. Combined treatment with brachytherapy and external beam radiation therapy is sometimes recommended for more aggressive cancers.
Hormonal Therapy:
Because most prostate cancers require testosterone to grow or spread, treatments that block the effects of this hormone (hormonal therapy) can slow progression of the tumors. Hormonal therapy is commonly used to delay the spread of the cancer that has come back after surgery or radiation therapy or to treat widespread (metastatic) prostate cancer. Hormonal therapy is sometimes combined with other treatments. It is not curative. Hormonal therapy can prolong life as well as decrease symptoms. Eventually, however, hormonal therapy becomes ineffective, and the disease progresses.
Hormonal drugs used to treat prostate cancer in the United States include leuprolide, goserelin, and buserelin, which prevent the pituitary gland from stimulating the testes to make testosterone. These drugs are administered by injection in a doctor's office every 1, 3, 4, or 12 months, usually for the rest of the man's life. For some men, this treatment may only be given for a year or two and possibly resumed at a later time.
Drugs that block testosterone's effects (such as flutamide, bicalutamide, and nilutamide) may also be used. These drugs are taken daily by mouth.
Side effects of hormonal therapy may include hot flashes, osteoporosis, loss of energy, reduction in muscle mass, fluid weight gain, reduction of libido, decrease in body hair, erectile dysfunction, and breast enlargement (gynecomastia).
The oldest form of hormonal therapy involves the removal of both testes (bilateral orchiectomy). The effects of bilateral orchiectomy on testosterone level are equivalent to those produced by leuprolide, goserelin, and buserelin. The physical and psychologic effects of bilateral orchiectomy and other hormonal therapies make these therapies difficult for some men to accept.
Hormonal therapy usually becomes ineffective within 3 to 5 years in men with widespread prostate cancer. When cancer eventually progresses despite hormonal therapy, most men die within 1 or 2 years. When hormonal therapy fails (hormone resistance), alternative hormone drugs or chemotherapy may be tried.
Other Treatments:
Chemotherapy is used in advanced cases when hormonal therapy has failed. Mitoxantrone, estramustine, and taxane drugs (such as docetaxel) can be used. Corticosteroids and the antifungal drug ketoconazole may also help relieve symptoms. Other treatments are being studied.
|
|
 | | |
| Common Methods and Strategies for Treating Prostate Cancer |
|
Characteristics of the Cancer
|
Treatment Strategy
|
Method of Treatment
|
|
Small, slow-growing cancer, confined to prostate in men expected to live many years
|
Curative treatment (to remove all traces of the cancer)
|
Surgery or radiation therapy
|
|
Small, slow-growing cancer, confined to prostate in men not expected to live many years
|
Active surveillance (to monitor and watch for symptoms)
|
No treatment
|
|
Large or fast-growing cancer, confined to prostate
|
Curative treatment
|
Surgery or radiation therapy
|
|
Cancer spread to areas around the prostate, but not to distant areas
|
Curative treatment
|
Radiation therapy
|
|
Widespread cancer
|
Palliative treatment (to relieve symptoms primarily rather than cure the cancer)
|
Hormonal therapy
|
|
Follow-up:
After all forms of treatment, PSA levels are measured at regular intervals (usually every 3 to 4 months for the first year, and then every 6 months for the rest of the man's life). By 1 month after surgery, PSA should not be detected. Following radiation therapy, PSA decreases more slowly and usually does not become undetectable but should remain stable at a low level. Increases in the PSA level may indicate that the cancer has recurred. Digital rectal examination is done at the same time in men who have a prostate gland.
Last full review/revision October 2008 by Gerald L. Andriole, MD
| 
