| Summary: | For colorectal cancer screening, the predictive value of distal
findings in the ascertainment of proximal lesions is not fully established. The
aims of this study were to assess distal findings as predictors of advanced
proximal neoplasia and to compare the predictive value of endoscopy alone vs.
combined endoscopic and histopathologic data. METHODS: Primary colonoscopy
screening was performed in 2210 consecutive, average-risk adults. Age, gender,
endoscopic (size, number of polyps), and histopathologic distal findings were
used as potential predictors of advanced proximal neoplasms (i.e., any adenoma >
or =1 cm in size, and/or with villous histology, and/or with severe dysplasia or
invasive cancer). Polyps were defined as distal if located in the descending
colon, the sigmoid colon, or the rectum. Those in other locations were designated
proximal. RESULTS: Neoplastic lesions, including 11 invasive cancers, were found
in 617 (27.9%) patients. Advanced proximal neoplasms without any distal adenoma
were present in 1.3% of patients. Of the advanced proximal lesions, 39% were not
associated with any distal polyp. Older age, male gender, and distal adenoma were
independent predictors of advanced proximal neoplasms. The predictive ability of
a model with endoscopic data alone did not improve after inclusion of
histopathologic data. In multivariate logistic regression analysis, the
predictive ability of models that use age, gender, and any combination of distal
findings was relatively low. The proportion of advanced proximal neoplasms
identified if any distal polyp was an indication for colonoscopy was only 62%.
CONCLUSIONS: A strategy in which colonoscopy is performed solely in patients with
distal colonic findings is not effective screening for the detection of advanced
proximal neoplasms in an average-risk population
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