Screening Sigmoidoscopy and Colorectal Cancer Mortality

Background: Sigmoidoscopy may reduce colorectal cancer mortality by identifying both cancers and precursor lesions (including polyps) for treatment; however, evidence regarding the efficacy of this technique as a screening procedure is extremely limited. Purpose: In the absence of data from radomized controlled trials, we performed a retrospective case control study to determine if sigmoidoscopy screening is assoicated with a reduation in colorectal cancer mortality. Methods: The medical records of 66 members of the Greater Marshfields Community Health Plan(GMCHP)who died of large -bowel cancer from 1979 to 1988 were reviewed for history of screening for colorectal cancer (case subjects). For comparison, the records of 196 GMCHP members of similar gender, age, and enrollment duration were randomly selected for review (control subjects). Results: History of screening sigmoidosciopy was much less common among case subjects (10%) than among control subjects (30%); Rist for death from colorectal cancer was reduced among individulas having had a single examination by screening sdigmoidoscopy (odds ratio=0.21; 95% confidence interval =0.08–0.52), compared with the risk for those who never had one. The reduction in risk appeared to be limited to tumbers in the rectum and distal colon. Neither fecal occult boold testing nore ditital rectal rectal examination was associated with a reduction in colorectal cancer mortal; ity. Conclusions: These results suggest that screening sigmoidoscopy can substantially reduce mortality from cancers of the recrum and distal colon.[J Natl Cancer Inst 84: 1572–1575, 1992]