What Is Prostate Cancer?
Prostate cancer is the growth of malignant cells in the prostate, a walnut-size gland located just below the bladder in men, which produces about 30 percent of the fluid portion of semen. Prostate cancer is common: Men have a lifetime chance of between one in 10 and one in 13 of developing the disease.
It is the most commonly diagnosed male cancer and the second leading cause of male cancer deaths. Indeed, autopsy studies have shown that 60 to 70 percent of all men who reach the age of 80 have at least some microscopic evidence of prostate cancer. Prostate cancer may be confined to the prostate or it may spread (metastasize) to tissues near the prostate, to the lymph node, and to more distant parts of the body, such as the bones or lungs. Symptoms do not occur until the cancer has spread beyond the prostate. However, today the diagnosis of prostate cancer at an advanced stage is unusual because of widespread screening for the disease with the PSA test.
Because prostate cancer tends to grow very slowly and takes years to spread, immediate and aggressive treatment may not be advised in older men. For such patients a diagnosis of prostate cancer may warrant a strategy of “active surveillance.” This involves regular examinations and blood tests, but treatment is undertaken only if evidence indicates tumor growth.
The specific treatment plan depends upon a number of factors: the patient’s age, the characteristics of the cancerous cells, the size of the tumor, whether cancer appears to have spread to other sites, and the risk of complications. Prostate cancer may be cured by removing the prostate gland or treating it with radiation before the cancer has spread. However, much controversy prevails about when to advise treatment because it is not possible to predict which cancers will spread and which will not. There is no cure once the cancer has spread beyond the prostate—though in some cases prostate cancer never spreads. In general, the outlook is good when the cancer is detected early.
Who Gets Prostate Cancer?
According to the American Cancer Society, prostate cancer is the most common type of cancer in men in the United States, other than skin cancer. The National Cancer Institute estimates that about 238,000 new cases were diagnosed in 2013 and about 29,700 men died of the disease. Prostate cancer is the second leading cause of cancer death in men, exceeded only by lung cancer.
Prostate cancer typically causes no symptoms in its early stages. But as the cancer causes the prostate to grow larger, a man may experience the following symptoms:
- Frequent or urgent need to urinate; delayed or interrupted urinary stream; dribbling.
- Pain upon urination.
- Blood in the urine.
- Painful or bloody ejaculation.
- Erectile dysfunction (impotence).
- Pain in the pelvis or lower back (from cancer that has spread beyond the prostate).
- The cause of prostate cancer is unknown, but age, family history, and race are the strongest risk factors.
- Age: The incidence of prostate cancer (rate of newly diagnosed cancer) increases faster with age than any other form of cancer.
- Family history: A family history of prostate cancer and early age at onset (under age 55) within a family increase the risk that a male will develop the disease.
- Race: African Americans have a one-and-a-half times greater incidence of prostate cancer than whites.
- The role of lifestyle factor, especially diet, has been widely researched, but without definitive results. Many studies have found a higher risk of prostate cancer among men with a higher fat intake, especially saturated fat from animal products. A high intake of cruciferous vegetables, such as cabbage and broccoli, appear to lower the risk of prostate cancer. Obesity is known to increase the risk of some types of cancer, but it is unclear whether it influences the development of prostate cancer specifically.
What If You Do Nothing?
Once prostate cancer has been diagnosed, determining the extent of the cancer is important for predicting the course of the disease and in choosing the best course of action. It’s understandable that the first instinct for many men diagnosed with prostate cancer is to assume that aggressive treatment should begin right away. But if you are at low or very low risk for developing advanced prostate cancer without treatment, don't be surprised if your doctor recommends doing what seems to be nothing. Some cancers pose a very low risk, especially in older men whose cancers are unlikely to become life threatening—and in these cases, no treatment, at least initially, may be the recommended option. But even these low-risk cancers need to be regularly monitored to determine whether the cancer is progressing—a strategy called “active surveillance” (see Treatment).
- Patient history and physical examination, including a digital rectal examination.
- Blood tests. The prostate specific antigen (PSA) blood test is the most useful test for early detection. PSA, an enzyme secreted by the cells lining the prostate, functions to liquefy semen after ejaculation. Normally, little PSA enters the blood, but prostate cancer tends to boost levels of PSA in the bloodstream. However, since nonmalignant abnormalities such as benign prostatic hyperplasia (BPH, or prostate enlargement) and prostatitis may also cause increased blood levels of PSA, other tests are necessary to confirm the diagnosis. Researchers have also developed ways of improving the PSA test’s accuracy—for example, taking the size of a man’s prostate into account (PSA density), measuring annual changes in PSA values (PSA velocity), or measuring the amount of PSA that is not attached to a protein (free PSA).
- Prostate biopsy is necessary to confirm the diagnosis. Transrectal ultrasonography (ultrasound scan with a rectal probe) allows visual imaging of the prostate and accurate placement of biopsy needles to obtain tissue samples. Typically 12 areas of small tissue samples are obtained with a needle inserted into the prostate through the rectum, guided by ultrasound.
- If an ultrasound guided prostate biopsy is inadequate, MRI-guided biopsy may be done to target suspicious areas.
- If biopsy results indicate cancer, additional diagnostic tests may be needed to determine the extent of the disease—how far the cancer has spread. A pathologist will assign a Gleason score to the cancer, which provides an estimate of how aggressive the cancer is. Depending on the Gleason score and PSA results, imaging studies (CT scan or bone scan) may be conducted to determine whether the cancer has spread to distant sites.
- For men with very-low- to low-risk cancers, active surveillance—which involves regular doctor visits and testing to monitor the progress of the tumor, with more aggressive treatment initiated when warranted—is a viable option for management of prostate cancer. Because prostate cancer generally progresses slowly, active surveillance is less risky in older men with favorable-risk disease. Therefore, the best candidates for active surveillance are men who have very-low-risk localized cancers or those with additional comorbidities. (Many men aged 65 and older are very healthy, and age alone does not exclude treatment. The American Urological Association suggests that men who benefit from treatment of prostate cancer are those who have at least a 10-year life expectancy.) If there are signs that your disease has progressed, you and your doctor would then pursue one of the following definitive treatment options.
- For men whose cancers are intermediate- or high-risk, total surgical removal of the prostate gland (radical prostatectomy) is the most common treatment. Radical prostatectomy offers the possibility of a cure only if the cancer has not spread to the seminal vesicles, the lymph nodes, or to a distant site such as bone. The procedure can be done as open surgery or performed via laparoscopy, with or without the use of robotic equipment, using tiny instruments and a tiny camera inserted through small incisions in the abdomen. A better understanding of the location of structures important for erectile function and urinary control has greatly reduced the risk of impotence and incontinence. After radical prostatectomy, PSA testing is performed to evaluate the success of the surgery and to monitor for disease recurrence.
- External bean radiation therapy involves aiming beams of radiation at the prostate to destroy cancerous cells. It is a treatment option for men with localized prostate cancer or locally advanced disease. External beam radiation may also be used as an adjuvant therapy—that is, performed after radical prostatectomy. The complications of radiation therapy are primarily adverse effects on the urinary tract and bowel. However, these effects usually disappear days to weeks after treatment is completed.
- Brachytherapy is another type of radiation treatment in which radioactive seeds are implanted directly into the prostate through the skin between the scrotum and rectum under ultrasound guidance. The pellets emit radiation for several months, and then remain harmlessly in the body. Brachytherapy is appropriate for men with early-stage, local prostate cancer (very low to low risk) or it can be used in conjunction with external radiation therapy.
- In advanced cases in which the cancer has spread, or in men whose cancer is expected to spread, hormonal therapy to block the release or function of male hormones, especially testosterone, can slow the growth of prostate cancer and thus minimize or arrest the further spread of the cancer. A variety of medications can also be used to interfere with the body’s production of testosterone.
- Chemotherapy is used when hormonal therapy is unable to control tumor growth.
- There is no known way to prevent prostate cancer. Some drugs have been investigated for prostate cancer prevention, but none have proven to be effective.
- There has been much debate in recent years about screening healthy men in an effort to detect prostate cancer in its earliest stages. Even though PSA screening has the potential to save lives, most of the cancers detected as a result of PSA testing are not aggressive and will never pose a serious health threat—yet the testing can lead to multiple biopsies and treatments that can produce serious long-term side effects. Therefore, men and their doctors must decide together whether prostate cancer screening is appropriate after a discussion of its benefits and risks. Such a discussion should take place when a man turns 50, or earlier if he is at high risk. Men at high risk are African Americans or men who have a first-degree relative (father or brother) with prostate cancer. For these men, screening should begin at the age of 40.
When To Call Your Doctor
- Contact your doctor if you experience difficult, painful, or unusually frequent urination. Also discuss screening for prostate cancer with your doctor when you turn age 50—earlier if you are at high risk (for example, if you have a family history of prostate cancer).
Reviewed by Sovrin M. Shah, M.D., F.A.C.S., Assistant Professor of Urology, Icahn School of Medicine at Mount Sinai, Pelvic Medicine and Reconstructive Surgery, Sol and Margaret Berger Department of Urology, Mount Sinai Beth Israel, and Phillips Ambulatory Care Center, New York, NY. Review provided by VeriMed Healthcare Network.