Inadequate sigmoidoscopy tied to colorectal cancer risk
Last Updated: August 26, 2005



NEW YORK (Reuters Health) - The results of study of more than 55,000
patients who underwent flexible sigmoidoscopy indicate that
inadequate insertion leads to a greater risk of subsequent colorectal
cancer, researchers report.


"The effectiveness of sigmoidoscopy as a colorectal cancer screening
test is dependent upon an adequate depth of insertion of the
sigmoidoscope," lead investigator Dr. V. Paul Doria-Rose told Reuters
Health. "We observed a threefold increase in the risk of subsequent
colorectal cancer among those who had a sigmoidoscopy examination in
which the sigmoidoscope was inserted to less than 40 centimeters."

Dr. Doria-Rose at the Fred Hutchinson Cancer Research Center in
Seattle and colleagues studied data for 55,791 members of a
Californian health maintenance organization screened as part of a
colon cancer prevention program. The findings are published in the
September issue of Gut.

Compared with participants between the ages of 50 and 59 years, those
who were 80 years or older had a relative risk of 2.6 for having an
inadequate examination. This was also true of women in general
(relative risk, 2.3).

The risk of distal colorectal cancer was increased approximately
threefold in those in whom baseline sigmoidoscopy did not reach 40
cm. There was a smaller increased risk for insertions of 40 to 59 cm.

Thus, concluded Dr. Doria-Rose, "because women and older individuals
had more than double the risk of having an incomplete sigmoidoscopy,
physicians should take special care to ensure a complete examination
in these groups, or, failing this, should consider an alternate
screening test such as colonoscopy or barium enema."