As of Tuesday, June 4, 2013
DEAR DOCTOR K: I recently had a PSA test and my levels came back elevated. I’m scheduled to have a prostate biopsy. What can I expect?
DEAR READER: The prostate-specific antigen (PSA) blood test is a screening test designed to detect prostate cancer before symptoms develop. An elevated PSA value can suggest that cancer may be present. But only a prostate biopsy can confirm the actual presence of cancer.
A prostate biopsy involves removing snippets of tissue from the prostate and checking them for cancerous cells under a microscope. Your prostate gland lies right next to your rectum, and the rectum is a passageway inside your body.
During the biopsy, your doctor will insert an ultrasound probe into your rectum. The ultrasound probe sends out sound waves that travel into the prostate and bounce back like an echo in a canyon. When they bounce back, they create a picture of your prostate gland. The picture shows the parts of the prostate that look like they might have cancer. This helps identify the best targets for the biopsy.
Guided by the ultrasound picture, the doctor uses a spring-loaded “biopsy gun” that directs a needle into the part of the prostate that looks cancerous. The device quickly sends a needle through your rectal wall and into the prostate. The needle removes small tissue samples — a typical biopsy removes 10 to 12 samples. When the needle is withdrawn from the body, the prostate tissue inside the needle is examined with a microscope to look for cancer.
You may feel a slight pinch as the needle punches into the prostate gland and takes the sample. Most men feel only mild to moderate discomfort.
Possible risks of a prostate biopsy include:
— erectile problems
— blood in the urine or stool
— short-term rectal bleeding
— blood in the semen
— difficulty urinating
— urinary incontinence
— urinary tract or prostate gland infection
If your biopsy result is positive, that means it has confirmed the presence of cancer in your prostate. If the biopsy specimen shows cancer, it’s cancer. But some prostate cancers just sit there for the rest of your life and never cause trouble, whereas others do cause problems. The main question your doctor asks when the biopsy is positive: What kind of prostate cancer is this?
The detailed biopsy findings will help you and your doctor decide what kind of prostate cancer you have, the extent and location of the cancer, and how malignant the cells look. This information helps your doctor determine how aggressive your cancer will be and the best course of action.
If no cancerous cells are found in the samples, that’s a good sign. But there’s still some room for doubt. About 10 percent of biopsies are “false negatives.” This means they have missed existing cancer.
Yes, the prostate biopsy can have side effects and can sometimes miss cancer. But the development of ultrasound pictures and biopsy guns and needles has made the diagnosis of prostate cancer much more accurate and has saved many lives.
Dr. Komaroff is a physician and professor at Harvard Medical School. To send questions, go to AskDoctorK.com, or write: Ask Doctor K, 10 Shattuck St., Second Floor, Boston, MA 02115.