PROSTATE CANCER About prostate specific antigen (PSA) The prostate specific antigen (PSA) test is a blood test that measures the level of PSA in the bloodstream. PSA is a substance produced by the prostate gland. Elevated levels of PSA in the blood can indicate the presence of prostate cancer, although other conditions affecting the prostate can also cause an increase in PSA levels. Typically, a higher PSA level suggests a higher likelihood of a prostate issue. However, it's important to note th