A prostate-specific antigen (PSA) test measures the amount of prostate-specific antigen in the blood. PSA is released into a man's blood by his prostate gland. Healthy men have low amounts of PSA in the blood. The amount of PSA in the blood normally increases as a man's prostate enlarges with age. PSA may increase as a result of an injury, a digital rectal exam, sexual activity (ejaculation), inflammation of the prostate gland (prostatitis), or prostate cancer.

Prostate cancer often grows very slowly, without causing major problems. Detecting prostate cancer early and treating it may prevent some health problems and reduce the risk of dying from the cancer. However, some treatments for prostate cancer can cause other problems, such as controlling urination (incontinence) or erection problems (erectile dysfunction). Some men may choose not to have a PSA test or treat prostate cancer if it is detected. For example, a man older than age 75 who has no bothersome symptoms of prostate cancer may choose not to treat the cancer if it is found, so he would not need a PSA test.

Should I have a prostate-specific antigen (PSA) test to screen for prostate cancer?

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Why It Is Done

The prostate-specific antigen (PSA) test is done to:

• Watch prostate cancer and see if treatment is working. If PSA levels increase, the cancer may be growing or spreading. PSA is usually not present in a man who has had his prostate gland removed. A PSA level that rises after prostate removal may mean the cancer has returned or has spread.
• Check if cancer may be present when results from other tests, such as a digital rectal exam, are not normal. A PSA test does not diagnose cancer, but it can be used along with other tests to determine if cancer is present.
• Check men for prostate cancer. Experts disagree on the usefulness of PSA testing as a screening tool for prostate cancer. If a PSA test is used for screening, it is usually done for men older than age 50 or for those at high risk for prostate cancer, such as men with a family history of prostate cancer, or for African-American men who have a higher chance of developing cancer than other men. Since other common medical conditions, such as prostatitis, can cause high PSA levels, a prostate biopsy is needed to confirm a diagnosis of cancer.