Related topics: •  Colorectal Cancer •  Digestive Disorders Center •  Digital Rectal Exam for Prostate Cancer

A digital rectal exam (DRE) is a simple, potentially life-saving procedure. It's also something that most people would rather avoid. If your doctor recommends a DRE, try to put your squeamishness aside and look at the big picture. A few moments of discomfort could be the key to a healthy future.

The exam is very straightforward: Your doctor will slide a gloved, well-lubricated finger into your rectum to feel for anything out of the ordinary, such as lumps or hardness that may indicate a hidden condition. It lasts less than a minute and usually doesn't cause any pain, although there might be some slight soreness afterwards.

The digital rectal exam is a valuable tool against one very deadly disease: prostate cancer. A DRE may also sometimes help doctors find tumors in the lower part of the colon, although other tests are necessary to verify colorectal cancer. With luck, the exam can help physicians detect these diseases in earlier, more treatable stages.

When screening for rectal cancer, your doctor feels for growths on the lining of the rectum. The technique can detect both precancerous polyps and full-blown tumors.

If you're a man, your doctor can use the DRE to check your prostate gland for unusual swelling, lumps, or areas of hardness, all potential red flags for cancer. If your prostate is larger than normal, you may have benign prostatic hyperplasia, a very common, noncancerous condition that can make it difficult for you to urinate. If your prostate is tender when it's touched, the gland may be infected, a condition called prostatitis.

Digital rectal exams are helpful, but they can't tell your doctor everything. In most cases, a doctor will run additional tests to get the full story.

Because fewer than 10 percent of all colorectal cancers occur within reach of a finger, your doctor will want to combine a DRE with a test that looks for blood in your stool (such as a fecal occult blood test). He or she may also order a colonoscopy or sigmoidoscopy (in which a flexible tube with a tiny camera on the end is used to explore the colon), or have a barium enema x-ray taken. If the DRE detects a growth, your doctor will order further tests to see if it's a polyp or a tumor.

Sometimes tumors on the prostate gland can also lie just out of reach. According to the American Urological Association, most prostate cancers are detected with a prostate specific antigen (PSA) blood test.

If either the DRE or the PSA test results are abnormal, the doctor can collect a biopsy, or sample, of the prostate for further testing. A biopsy is the only way to confirm whether or not cancer is present.

Because rectal cancer and prostate diseases are rare in people under 40, young patients usually don't need digital rectal exams. Some gynecologists conduct DREs as part of a routine pelvic exam in young women, but a study published in the Journal of Family Practice found that this rarely uncovers any hidden disease.

There are some cases where DRE may be appropriate for young patients. People with a family history of adenomatous polyposis, a rare inherited disorder characterized by cancer of the colon and rectum, may need to start screening as early as age 10. Also, anyone over 25 who has symptoms of rectal cancer may need a DRE along with a colonoscopy or other test.

Experts agree that a DRE isn't the best way to find colon cancer. To help diagnose colon cancer, the US Preventive Services Task Force (USPSTF), an independent group of experts that reviews the value of medical tests for the US Public Health Service, advocates fecal occult blood testing, colonoscopy, or sigmoidoscopy in people 50 to 75-years-old.

The picture for prostate screening is also murky. The American Cancer Society does not recommend routine testing for prostate cancer, but it does recommend that all men be offered annual DREs and PSA tests starting at age 50. African Americans and men with a family history of prostate cancer -- two groups at especially high risk for the disease -- should talk with their doctors about whether they should begin annual testing at 45. The USPSTF notes that there is not enough evidence to determine whether prostate screening improves health outcomes in men younger than age 75. Therefore, the USPSTF also recommends that doctors discuss the potential benefits and risks of PSA screening with patients younger than 75, and they not screen patients over 75.

You can cut through the confusion by talking to your doctor. If he or she recommends a DRE to screen for rectal polyps or cancer, find out why. If you're over 40 and your doctor hasn't suggested a DRE, find out why not. Ask your doctor if PSA screening is necessary and how often you should be screened. Working together, you can develop a sensible, workable approach to screening.

-- Chris Woolston, M.S., is a health and medical writer with a master's degree in biology. He is a contributing editor at Consumer Health Interactive, and was the staff writer at Hippocrates, a magazine for physicians. He has also covered science issues for Time Inc. Health, WebMD, and the Chronicle of Higher Education. His reporting on occupational health earned him an award from the northern California Society of Professional Journalists.

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Last updated July 31, 2009
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