Significance of small distal adenoma for detection of proximal neoplasms in the colorectum

Background: The significance of the small distal tubular adenoma detected by sigmoidoscopy as a predictor of proximal neoplasm remains controversial. The aim of this study was to examine the prevalence of proximal neoplasms in patients with and without distal neoplasms. Methods: This is a retrospective study of 3131 asymptomatic middle-aged men who underwent total colonoscopy. For 812 men with colorectal neoplasms characteristics of the identified neoplasms were determined. Results: The prevalence of proximal neoplasms in patients with small distal tubular adenoma was 20% (92 of 461), whereas the prevalence of proximal neoplasms in patients without distal neoplasms was 11.5% (301 of 2620). The prevalence of advanced proximal neoplasms in patients with small distal tubular adenoma and without distal neoplasm was 1.3% and 0.8%, respectively. In the 29 patients with advanced proximal neoplasms, only 6 (21%) had a small distal tubular adenoma. Conclusions: The presence of small distal tubular adenomas may provide a clue to the presence of small proximal tubular adenomas. However, the majority of advanced proximal neoplasms (79%) do not have a synchronous small distal tubular adenoma.