A biopsy, or sampling of prostate tissue, is currently the only definitive method of diagnosing prostate cancer. A biopsy is performed on all men with a strong suspicion of cancer based on PSA test results and other factors. A biopsy takes about 35 minutes to perform and is done as an outpatient procedure. Biopsies are generally well-tolerated with minimal pain and bleeding. Before the biopsy, the patient undergoes an enema and is given an antibiotic. Lidocaine is used to deaden the nerves that lie alongside the prostate gland to make the procedure more comfortable.
A transrectal ultrasound (TRUS) probe is inserted into the rectum so the oncologist can view the prostate, which takes about 10 minutes. Then, a fine-gauge, spring-loaded biopsy needle is used to remove six to 10 tiny “core” samples of tissue from specific, predetermined areas on the prostate gland. The biopsy specimens take about three to seven days to process.
Gleason Grading System
Prostate cancers contain several types of cells that appear differently under a microscope. The Gleason grading system uses the numbers 1– 5 to “grade” the most common (primary) and next most common (secondary) cell types found in a tissue sample. Together, the sum of these two numbers is the Gleason score, ranging from 2–10, and tells the physician how aggressive the tumor appears under the microscope. The higher the Gleason score, the more aggressive the cancer. The Gleason score is considered along with other factors to help select the most appropriate treatment for the patient.