The test for PSA measures the level of prostate-specific antigen (PSA) in the blood, which is a protein produced by the cells of the prostate gland. Doctors often use this test to screen for prostate cancer or to see if cancer has recurred in people with a history of the disease. The test, however, has its limitations, and doctors are divided as to actual value of the test.
Prostate-specific antigen (PSA) is a protein produced by the cells of the prostate gland. Because PSA is produced by the body and can be used to detect disease, it is sometimes called a biological marker or tumor marker.
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.
It is normal for men to have low levels of PSA in their blood; however, both prostate cancer and benign (noncancerous) conditions can increase these levels. As men age, both benign prostate conditions and prostate cancer become more frequent. The most common benign prostate conditions are:
- Prostatitis (inflammation of the prostate)
- Benign prostatic hyperplasia (BPH), or enlargement of the prostate.
There is no evidence that prostatitis or BPH cause cancer, but it is possible for a man to have one or both of these conditions and to develop prostate cancer as well.
PSA levels alone do 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.