Colorectal Cancer Screening: A Community Case-Control Study of Proctosigmoidoscopy, Barium Enema Radiography, and Fecal Occult Blood Test Efficacy

To examine the effectiveness of screening proctosigmoidoscopy, barium enema radiography, and the fecal occult blood test (FOBT) in decreasing colorectal cancer mortality in a community setting. In this population-based case-control study, cases comprised 218 Rochester, Minn, residents who died of colorectal cancer between 1970 and 1993. Controls were 435 age- and sex-matched residents who did not have a diagnosis of colorectal cancer. Screening proctosigmoidoscopy, barium enema radiography, and FOBT results were documented for the 10 years prior to and including the date of diagnosis of fatal colorectal cancer in cases and for the same period in matched controls. History of general medical examinations and hospitalizations was also recorded. Within the 10 years prior to diagnosis, the percentages of cases vs controls with at least 1 screening proctosigmoidoscopy were 23 (10.6%) of 218 cases vs 43 (9.9%) of 435 controls; at least 1 screening barium enema radiographic study was done in 12 (5.5%) of 218 vs 25 (5.7%) of 435. Within 3 years prior to diagnosis, the percentages of cases vs controls with at least 1 screening FOBT were 27 (12.4%) of 218 vs 44 (10.1%) of 435. Adjusted odds ratios were 1.04 (95% confidence interval [CI], 0.21-5.13) for proctosigmoidoscopy (distal rectosigmoid cancers only), 0.67 (95% CI, 0.31-1.48) for barium enema radiography, and 0.83 (95% CI, 0.45-1.52) for FOBT over the above time periods. In this case-control study within a community setting, a colorectal cancer-specific mortality benefit could not be demonstrated for screening by FOBT, proctosigmoidoscopy, or barium enema radiography. Screening frequency was low, which may have contributed to the lack of measurable effects.