The PSA test is a blood test used primarily to screen for prostate cancer. The test measures the amount of prostate-specific antigen (PSA) in your blood. PSA is a protein produced by both cancerous and noncancerous tissue in the prostate, a small gland that sits below the bladder in men. PSA is mostly found in semen, which also is produced in the prostate. Small amounts of PSA ordinarily circulate in the blood. The PSA test can detect high levels of PSA that may indicate the presence of prostate cancer. However, many other conditions, such as an enlarged or inflamed prostate, can also increase PSA levels. Therefore, determining what a high PSA score means can be complicated. There is a lot of conflicting advice about PSA testing. To decide whether to have a PSA test, discuss the issue with your doctor, considering your risk factors and weighing your personal preferences.
Why it’s done
Prostate cancer is common, and a frequent cause of cancer death. Early detection may be an important tool in getting appropriate and timely treatment.
Men with prostate cancer may have elevated levels of PSA. However, many noncancerous conditions also can increase the PSA level. The PSA test can detect high levels of PSA in the blood but doesn’t provide precise diagnostic information about the condition of the prostate.
The PSA test is only one tool used to screen for early signs of prostate cancer. Another common screening test, usually done in addition to a PSA test, is a digital rectal exam.
In this test, your doctor inserts a lubricated, gloved finger into your rectum to reach the prostate. By feeling or pressing on the prostate, the doctor may be able to judge whether it has abnormal lumps or hard areas.
Neither the PSA test nor the digital rectal exam provides enough information for your doctor to diagnose prostate cancer. Abnormal results in these tests may lead your doctor to recommend a prostate biopsy.
During this procedure, samples of tissue are removed for laboratory examination. A diagnosis of cancer is based on the biopsy results.