All Tests

Prostate specific antigen (PSA) is a protein produced primarily by cells in the prostate, a small gland that encircles the urethra in males and produces a fluid that makes up part of semen. Most of the PSA that the prostate produces is released into this fluid, but small amounts of it are also released into the bloodstream. This test measures the amount of PSA in the blood.

The PSA test is used as a tumor marker to screen for and to monitor prostate cancer. It is a good tool but not a perfect one, and most experts agree that screening should be done on asymptomatic men only after thorough discussions with their healthcare providers on the benefits and risks and after informed decisions are made to undergo screening. Elevated levels of PSA are associated with prostate cancer, but they may also be seen with prostatitis and benign prostatic hyperplasia (BPH). PSA levels tend to increase in all men as they age, and men of African American heritage may have levels that are higher than other men, even at earlier ages.

PSA is not diagnostic of cancer. The gold standard for identifying prostate cancer is the prostate biopsy, collecting small samples of prostate tissue and identifying abnormal cells under the microscope. (Read the article on Anatomic Pathology for more information on biopsies.) The total PSA test and digital rectal exam (DRE) are used together to help determine the need for a prostate biopsy.

The goal of screening is to detect prostate cancer while it is still confined to the prostate. Once the presence of prostate cancer is confirmed by biopsy, another decision must be made with regard to treatment. Prostate cancer is relatively common in men as they age and many, if not most, of the tumors are very slow-growing. While prostate cancer is the number two cause of death in men, the slow-growing type is an uncommon cause of death. A pathologist may be able to help differentiate between slow-growing cases and cancers that are likely to grow aggressively and spread to other parts of the body (metastasize).