What is a prostate biopsy?
For many men 50 and over, digital rectal exams (DREs) have become a routine part of the annual checkup, as have prostate specific antigen (PSA) tests. These tests can uncover signs of prostate cancer, a disease that kills roughly 29,000 Americans each year. But before a doctor can make the diagnosis, he needs to do another procedure: the prostate biopsy. To confirm the presence of prostate cancer, a doctor uses a needle to collect a sample of cells from the prostate. This sample is then examined by a pathologist, an expert who can distinguish cancerous from noncancerous cells.
As reported in the January 2002 issue of Urology, widespread use of the PSA test has led to a boom in biopsies. With more and more men undergoing biopsies, doctors are making every effort to ensure the procedure is as safe, comfortable, and accurate as possible.
How is a biopsy performed?
A prostate biopsy is a simple procedure. In most cases, the whole process takes about 20-30 minutes. Usually, as you lie on an exam table, a doctor will insert a slender ultrasound device into your rectum. The device will emit sound waves to produce an image of your prostate. This process is called transrectal ultrasound or TRUS.
Guided by the ultrasound image, your doctor will slide a tiny needle through your rectal wall and into the prostate. The key word is "tiny": According to the University of Pittsburgh Cancer Institute, prostate biopsy needles are only 1.2 millimeters in diameter.
Prostate tumors tend to be very small and can be located just about anywhere on the prostate. For this reason, doctors take samples from several different areas of the gland. The most common approach is to take 10 to 12 samples. However, some doctors will take as many as 45 samples in a search for cancer. This "saturation" approach can uncover tumors that regular biopsies miss. As you might imagine, patients undergoing such a comprehensive procedure have to be anesthetized first.
What are the side effects of a prostate biopsy?
By some accounts, a prostate biopsy hurts -- but not as much as you might think. Usually, the prostate itself isn't especially sensitive to pain. In most cases, anxiety over the biopsy causes more trouble than the biopsy itself. If your doctor is only collecting a few samples and doesn't think you need to be anesthetized, but you're concerned about pain, ask your doctor if it's possible to get a dose of a numbing agent to numb the area during the procedure. Lidocaine gel, a common pain reliever, can significantly improve a patient's comfort.
Many patients notice small amounts of blood in their urine, stools, or semen in the days after a biopsy. This is to be expected and is no cause for alarm. According to the University of Pittsburgh Cancer Institute, fewer than 1 percent of all patients develop severe bleeding or an infection of the prostate or urinary tract.
How accurate is a prostate biopsy?
As vividly described in a 2002 bulletin from Johns Hopkins University, prostate tumors are like a few small seeds scattered on a large strawberry. Whether a surgeon takes six biopsy samples, or a dozen or more, there's a chance that the cancer will be missed. In a study published in the September 2001 issue of the Journal of Urology, researchers performed biopsies on 820 men who had recently had negative biopsies. In 10 percent of the cases, the second biopsies turned up cancer. According to researchers at the Oregon Health and Science University Cancer Center, however, up to 25 percent of prostate biopsies give a false negative.
In other words, a negative biopsy is no guarantee that you are truly cancer-free. If you're over 50 and you have signs of prostate cancer, such as an enlarged prostate or a high PSA, your doctor may want to take another biopsy in the future. Researchers at a VA hospital in Oregon have developed a way to determine which patients need a second biopsy based on their PSA adjusted for prostate size. Even if you don't have any signs of cancer, you should continue to get regular PSA tests and digital rectal exams as recommended by your doctor.
2004 U.S. cancers by typemale," United States Cancer Statistics, Centers for Disease Control and Prevention.
University of Pittsburgh Cancer Institute. Prostate Needle Biopsy. February 2002.
Djavan B, et al. Safety and morbidity of first and repeat transrectal ultrasound guided prostate needle biopsies. The Journal of Urology. September 2001. 166: 856-860.
Harvard Medical School. Prostate ultrasound.
Issa, MM, et al. A randomized prospective trial of intrarectal lidocaine for pain control during transrectal prostate biopsy: the Emory University experience. Journal of Urology 2000: August; 164 (2):405.
Johns Hopkins Prostate Bulletin. 2002.
American Cancer Society. How Many Men Get Prostate Cancer? May 2006.
Mayo Clinic. Prostate biopsy. September 4, 2008.
OHSU Cancer Institute. VA researcher finds way to identify which men need a second biopsy. February 22, 2007.