SAN DIEGOIn the VA Cooperative Study 380, screening colonoscopy
found advanced adenomas in approximately 10% of asymptomatic
veterans, and approximately 20% to 40% of those patients had no
lesions within reach of a sigmoidoscope, depending on the insertion
depth of the scope.
However, 97% of the study population were men, and that left
researchers without adequate data about the efficacy of screening
colonoscopy in women.
We decided to duplicate the VA 380 study, but this time with
women only, said Brooks Cash, MD, a gastroenterology fellow at
the National Naval Medical Center, Bethesda. He presented the results
at an American Gastroenterological Association research forum held
during the Digestive Disease Week conference.
Subjects completed questionnaires about multiple risk factors for
adenomas prior to undergoing colonoscopy. The questions dealt with
age, race, alcohol use, tobacco use, NSAID use, and family history of
The study included consecutive asymptomatic women referred for
screening. Excluded were women who had had colonoscopy or barium
enema within the last 10 years, flexible sigmoidoscopy in the last 5
years, hematochezia within the last year, iron deficiency anemia, or
positive stool guiaics.
Dr. Cash said that the sample size calculations mirror that of the VA
Cooperative Study 380, with 215 completing the study thus far of a
planned 1,500. The mean age of these initial patients was 58.7 years;
15.8% had a positive family history, and 7.9% were black.
Of the 215 women screened, 40 women (18.6%) were found to have
adenomas during colonoscopy. Ten (4.65%) had advanced adenomas. Of
these 10, four had no adenomas within reach of the flexible sigmoidoscopy.
Had flexible sigmoidoscopy been the only screening test, those
proximal adenomas would have been missed, Dr. Cash said.
Based on our preliminary data, I think colonoscopy may be
preferable to flexible sigmoidoscopy for colorectal cancer screening
in asymptomatic women.
Age over 65 was the only significant risk factor for colorectal
cancer in this group, although alcohol use (more than 2 oz daily)
approached significance as an independent risk factor.