Harvard Men's Health Watch

On call: The digital rectal exam

Q. I just reviewed your article on PSA testing. After talking with my wife, I've decided to skip the PSA test when I go for my annual physical next month. But your article doesn't say much about rectal exams. Should I skip that also?

A. It's a good question. We didn't have much to say about the digital rectal exam (DRE) because we were focusing on studies that don't tell us much about the DRE. The Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial tested the combination of prostate-specific antigen (PSA) and DRE and found that the pair did not reduce the risk of dying from prostate cancer. The European Randomized Study of Screening for Prostate Cancer (ERSPC) was conducted in seven countries; all used the PSA, but only a few added DREs — and even these included DREs for just a portion of the nine-year trial. As you may recall, the ERSPC found that screening reduced prostate cancer deaths by 20%, but at the cost of treating 48 men unnecessarily to prevent one prostate cancer death.

The DRE is, of course, much simpler than the PSA blood test. The doctor inserts a well-lubricated gloved index finger into the patient's rectum, and then feels the prostate gland in a process called palpation. At the same time, the physician feels for rectal masses that might indicate rectal cancer or other abnormalities. In most cases, the exam takes less than 15 seconds, but immediately after the DRE, many docs will perform an additional step, using an inexpensive but very sensitive chemical test to check for traces of blood in a tiny fecal specimen. Because the test looks for amounts of blood too small to be visible to the eye, it's called the fecal occult blood test (FOBT).

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