Bowel cancer test often misses the mark in women (Reuters)

NEW YORK (Reuters Health) - When used for colorectal cancer screening in women without symptoms of the disease, flexible sigmoidoscopy will miss 65 percent of advanced colorectal lesions, a study shows.

As such, colonoscopy may be the preferred screening method in women, researchers contend in this week's issue of The New England Journal of Medicine.

These findings may not have a major impact in the US as colonoscopic screening is already becoming widespread, they note. However, in other countries, they could assume greater importance as this modality is not widely used.

Flexible sigmoidoscopy is a test in which a lighted instrument is used to examine the lower part of the colon near the rectum, often referred to as the distal colon. It differs from a colonoscopy in which the entire colon is examined.

In the study, colonoscopy was performed in 1463 women. A total of 240 women (15.7 percent) had a family history of colon cancer.

Advanced lesions seen in the lower part of the colon (the distal colon) were considered to be detectable by flexible sigmoidoscopy as were lesions in the upper part of the colon (the proximal colon) provided that small polyps were also present in the distal colon that would have led to colonoscopy.

According to Dr. Philip Schoenfeld, from the University of Michigan at Ann Arbor, and colleagues found that 72 women had advanced tumors on colonoscopy. If only flexible sigmoidoscopy had been performed, the disease would have been identified in just 25 of these women.

"In our opinion, colonoscopy is the preferred method of colorectal-cancer screening" in women without symptoms that are deemed to be at average-risk for developing the disease, the investigators conclude.

SOURCE: The New England Journal of Medicine, May 19, 2005.