What is the PSA blood test, and how is it used to screen for prostate cancer?
Prostate-specific antigen (PSA) is a protein produced by prostate tissue. An elevated PSA level in the blood may identify the presence of cancerous abnormalities of the prostate gland before symptoms are reported, and thus has been used as a screening test. The limitation of PSA as a diagnostic test is that PSA levels can be elevated in benign diseases of the prostate as well as in malignancies.
