One of the methods doctors sometimes use to check for the possibility of prostate cancer is a prostate-specific antigen blood test, or PSA, since many men with prostate cancer also have high levels of PSA in the blood. If blood test results show high levels of the substance in the bloodstream, the likelihood of prostate cancer being present increases.

Upon finding high levels of PSA in a blood test, your doctor will most likely recommend further testing or a biopsy. Doctors cannot diagnose prostate cancer on the results of a blood test alone, or even in conjunction with other diagnostic tests like digital rectal exams (DREs). In order for a diagnosis to be made, a biopsy of the prostate must be taken for microscopic examination in a lab. There, a pathologist can determine if the prostatic tissue indeed has cancerous cells developing and can diagnose the disease. The pathologist then puts the findings in a report which includes, among other information, the stage the prostate cancer has reached.