New Concerns About Colon Polyps?

By Andrew Mayer, M.D., Scripps Memorial Hospital La Jolla

For years, we’ve stressed to patients the need to screen for colon cancer, the second leading cause of cancer death in men and women, with colonoscopy. A recent study regarding potentially cancerous flat lesions within the colon emphasizes the importance for patients and physicians to be as diligent as possible when preparing for and performing colonoscopy.

Colonoscopy allows the physician to inspect and sample the tissue in the colon via a long, flexible tube with an attached camera. With the patient sedated, the tube is inserted through the anus and passed through the length of the colon. Images from the camera are displayed on a video monitor, which enables the physician to see polyps, which are abnormal growths within the colon, and other irregularities. Should any abnormalities be found, they may be biopsied or removed during the procedure.

A study published in the Journal of the American Medical Association (JAMA) reports that flat polyps, another type of abnormality found in the colon, may be overlooked during colonoscopy. Unlike conventional polyps, which are raised and easy to detect, these flat lesions look much like healthy tissue. What’s more, not only are they more common among Americans than previously suspected, they are more likely than raised polyps to become cancerous. Of the 1,819 military veterans included in the study, 9.35 percent of them had flat polyps. These flat lesions were five times as likely as raised polyps to harbor cancerous or precancerous tissue.

What does this mean to you as a patient? First of all, don’t panic—colonoscopy remains the “gold standard” for detecting and removing colon polyps. These most recent findings suggest that physicians and patients alike should make every effort to ensure that colonoscopy exams are performed as thoroughly as possible.

One of the most important factors is the preparation for the exam: patients follow a liquid diet and use strong laxatives to completely clear the colon prior to the exam. While this can be unpleasant, patients who don’t take the laxatives as directed may have residual waste in their colon during the exam. This is one of the main reasons why flat lesions may not be detected. Studies have found that bowel preparation is lacking in about 25% of colonoscopies. It is, therefore, vitally important to follow the preparation instructions exactly to enable the physician to get the clearest view possible of the intestinal lining.

Physicians also should take plenty of time to thoroughly examine the colon and look carefully for flat as well as raised polyps and other abnormalities. Some physicians may benefit from additional training to learn to spot and remove the indented or depressed growths in the bowel lining.

The JAMA study also raises questions about the effectiveness of virtual colonoscopy, also known as CT colonography or CT colonoscopy. Virtual colonoscopy uses a very thin tube inserted into the rectum to inflate the colon with air. Specialized scanning equipment takes images which are transferred to a video monitor, creating a detailed “virtual” picture of the inside of the colon. The physician may then look for the same abnormalities that would be seen with conventional colonoscopy. While the scanning equipment may detect protruding lesions such as raised polyps, it is much less likely to detect flat lesions.

If you’ve had a recent colonoscopy and the results were clear, you probably don’t need to have it repeated to look exclusively for flat lesions. Follow your physician’s recommendations for future screenings. But if you are worried about flat lesions, call your physician and express your concerns. If you are over age 50 and haven’t had a colonoscopy, now is the time to get one. And certainly, if you have symptoms such as rectal bleeding, a change in bowel habits, or weight loss, call your doctor right away.

Andrew Mayer, M.D., is a gastroenterologist at Scripps Memorial Hospital La Jolla. For more information or to schedule an appointment, please call 1-800-SCRIPPS (1-800-727-4777).