Colon cancer missed in simple screening test

May 18 2005

A new U.S. study has revealed that a commonly used screening tool for colon cancer, sigmoidoscopy, does not pick up precancerous growths in almost two-thirds of women and the failure rate is twice as high as in men.

The researchers were surprised to find that men and women do not develop polyps in the same area of the colon.

Apparently precancerous polyps in men tend to grow in the lower portion of the colon, whereas women's polyps tend to grow deeper in the colon, beyond a flexible sigmoidoscopy's reach.

As a result of this revelation, researchers are recommending that colonoscopy, which is a more reliable but more expensive test, be considered the preferred method for most women.

Dr. Phillip Schoenfeld, of the University of Michigan Medical School, the lead researcher, says that it is known that men and women develop symptoms differently and require different approaches with other diseases such as heart attacks, and colon cancer screening should be no exception.

Sigmoidoscope exams were already in question because they find growths in only 66 percent of average-risk men, and in this new women's study, the exams did even worse, detecting growths just 35 percent of the time.

Medical guidelines recommend either procedure for those above age 50 to detect early cases of colon cancer.

The study appears in current issue of the New England Journal of Medicine.