The yield of flexible fiberoptic sigmoidoscopy in the detection of asymptomatic colorectal neoplasia.

Recent evidence of a reduction in mortality rates from distal colorectal cancers in populations screened by rigid sigmoidoscopy suggests that further benefits may be achieved by the use of fiberoptic sigmoidoscopy as the screening modality. However, there is limited evidence as to the expected yield of neoplasia using the standard 60-cm instrument. The aim of this study was to determine the yield of neoplasia in an asymptomatic population in the at-risk age group undergoing fiberoptic sigmoidoscopy. Recruitment into the screening program was among State Department personnel. In total, 4,216 asymptomatic subjects (50-65 years) were offered flexible sigmoidoscopic screening performed following a simple enema bowel preparation. Those in whom a neoplastic condition was identified underwent further investigation (colonoscopy or barium enema). Of those offered screening 4,005 (95%) underwent the examination. Eleven carcinomas were detected at flexible sigmoidoscopy and two carcinomas were detected at further investigation in subjects with rectosigmoid polyps. The overall detection rate of carcinomas was 3.2 per 1,000 subjects screened. Histologically proven adenomas were detected in 217 subjects, 5.4% of the population screened. In this cohort of individuals flexible sigmoidoscopy appears to have been an acceptable form of screening. The detection rate of neoplasia, particularly colorectal adenomas, is higher than that reported from studies of fecal occult blood screening.