What is the prostate-specific antigen (PSA) test?
Prostate-specific antigen (PSA) is a protein produced by cells of the prostate gland. The PSA test measures the level of PSA in the blood. The doctor takes a blood sample, and the amount of PSA is measured in a laboratory. Because PSA is produced by the body and can be used to detect disease, it is sometimes called a biological marker or a tumor marker.
It is normal for men to have a low level of PSA in their blood; however, prostate cancer or benign (not cancerous) conditions can increase a man’s PSA level. As men age, both benign prostate conditions and prostate cancer become more common. The most frequent benign prostate conditions are prostatitis (inflammation of the prostate) and benign prostatic hyperplasia (BPH) (enlargement of the prostate). There is no evidence that prostatitis or BPH causes cancer, but it is possible for a man to have one or both of these conditions and to develop prostate cancer as well.
A man’s PSA level alone does not give doctors enough information to distinguish between benign prostate conditions and cancer. However, the doctor will take the result of the PSA test into account when deciding whether to check further for signs of prostate cancer.
Why is the PSA test performed?The U.S. Food and Drug Administration (FDA) has approved the use of the PSA test along with a digital rectal exam (DRE) to help detect prostate cancer in men 50 years of age or older. During a DRE, a doctor inserts a gloved finger into the rectum and feels the prostate gland through the rectal wall to check for bumps or abnormal areas. Doctors often use the PSA test and DRE as prostate cancer screening tests; together, these tests can help doctors detect prostate cancer in men who have no symptoms of the disease.
The FDA has also approved the use of the PSA test to monitor patients who have a history of prostate cancer to see if the cancer has recurred (come back). If a man’s PSA level begins to rise, it may be the first sign of recurrence. Such a “biochemical relapse” typically precedes clinical signs and symptoms of a relapse by months or years. However, a single elevated PSA measurement in a patient with a history of prostate cancer does not always mean the cancer has come back. A man who has been treated for prostate cancer should discuss an elevated PSA level with his doctor. The doctor may recommend repeating the PSA test or performing other tests to check for evidence of a recurrence. The doctor may look for a trend of rising PSA measurements over time rather than a single elevated PSA level.
It is important to note that a man who is receiving hormone therapy for prostate cancer may have a low PSA level during, or immediately after, treatment. The low level may not be a true measure of the man’s PSA level. Men receiving hormone therapy should talk with their doctor, who may advise them to wait a few months after hormone treatment before having a PSA test.
For whom might a PSA screening test be recommended?Doctors’ recommendations for screening vary. Some encourage yearly screening for men over age 50, and some advise men who are at a higher risk for prostate cancer to begin screening at age 40 or 45. Others caution against routine screening. Although specific recommendations regarding PSA screening vary, there is general agreement that men should be informed about the potential risks and benefits of PSA screening before being tested. Currently, Medicare provides coverage for an annual PSA test for all men age 50 and older.
Several risk factors increase a man’s chances of developing prostate cancer. These factors may be taken into consideration when a doctor recommends screening. Age is the most common risk factor, with nearly 63 percent of prostate cancer cases occurring in men age 65 and older (1). Other risk factors for prostate cancer include family history, race, and possibly diet. Men who have a father or brother with prostate cancer have a greater chance of developing prostate cancer. African American men have the highest rate of prostate cancer, while Asian and Native American men have the lowest rates. In addition, there is some evidence that a diet higher in fat, especially animal fat, may increase the risk of prostate cancer.
Key PointsFor more information about the Prostate-Specific Antigen (PSA) Test, click here. Or click here to readhow Buffett's Cancer Is Shaping National Dialogue
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