Doctors use a variety of tests to detect and diagnose prostate cancer, as stated by American Cancer Society. The first tests that catch prostate cancer are usually the digital rectal exam, or DRE, and the prostate-specific antigen, or PSA, blood test.
Cancer of the prostate is detected by doctors first through a PSA blood test or a DRE exam. The test used usually depends on the patient's comfort level with either one. A DRE exam involves placing two gloved fingers inside the rectum to feel the prostate gland for abnormalities. A PSA test requires a blood draw to look for levels of a specific protein produced primarily by the prostate gland. Low levels of the antigen could indicate cancer.
If either of these test are positive for prostate cancer, the doctor may want to perform a transrectal ultrasound and biopsy of the prostate gland. The TRUS uses a small ultrasound probe inserted into the rectum to create an image of the prostate gland. During this ultrasound the doctor takes about 12 small samples from the prostate with a special biopsy needle. These samples are examined by a pathologist who determines if the cells are cancerous and grades the cancer by its potential level of severity. This requires sending the samples to a lab, and diagnosis may take a few days.