Biopsy for Prostate Cancer

A core needle biopsy is the main method used to diagnose prostate cancer. A biopsy is a procedure in which a sample of tissue is removed and then examined under a microscope. The doctor will use transrectal ultrasound (TRUS) for guidance and insert a narrow needle through the wall of your rectum into several areas of your prostate gland. The needle then removes a cylinder of tissue, usually about 1/2-inch long and 1/16-inch across, that is sent to the laboratory to see if cancer is present.

Though the procedure sounds painful, it typically causes little discomfort because a special instrument called a biopsy gun inserts and removes the needle in a fraction of a second. The doctor can also numb the area with a local anesthetic. The procedure takes about 15 minutes and is usually done in the doctor's office. Several biopsy samples are often taken from different areas of the prostate. Anywhere from 6 to 13 samples are usually needed to determine if cancer is present and how much of the gland is affected, but as many as 18 samples may be taken from some patients. You may want to discuss the number of biopsies to be taken with your doctor before the procedure starts.

Unfortunately, even when taking more samples, biopsies can occasionally miss detecting cancer. This is known as a "false negative" result. If your doctor still strongly suspects you may have prostate cancer (due to a very high PSA level, for example) a repeat biopsy may be needed to help rule this out.

Some doctors will perform the biopsy through the perineum, the skin between the rectum and the scrotum. The doctor will place his or her finger in your rectum to feel the prostate and then insert the biopsy needle through a small incision in the skin of the perineum. The doctor will also use a local anesthetic to numb the area. Your biopsy sample will then be sent to a pathology laboratory. There, the pathologist (a doctor who specializes in diagnosing disease in tissue samples) will determine if there are cancer cells in your biopsy sample by examining it under the microscope. This analysis usually takes 1 to 3 days. If cancer is present, the pathologist will also assign it a grade.

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