Increase in Serrated Polyp Detection Rate Over Time in a Cohort of Average Risk Patients Undergoing Screening Colonoscopy

Abstract

Purpose: Serrated polyps represent precursor lesions in an alternative pathway to colorectal cancer which may account for 15% of all colorectal cancers diagnosed in the United States. Premalignant serrated polyps are frequently flat or sessile, subtle, located in the proximal colon and may be overlooked during colonoscopy. Awareness of the association of such lesions with risk for carcinoma has become generally known only in recent years. The aim of this study was to determine if the detection rate of serrated polyps in an average risk screening population has increased over time. Methods: Endoscopy and pathology reports were reviewed from all patients undergoing average risk colorectal neoplasia screening colonoscopies at Boston Medical Center from 2006 through 2008. Polyps were classified as adenoma (including tubular adenoma, tubulovillous and villous adenoma), serrated polyp (including hyperplastic polyp, serrated adenoma and sessile serrated adenoma), normal mucosa, or other. Polyp detection was summarized with count statistics and reported as rate per 100 screening colonoscopies. Differences in polyp distribution were assessed with the χ2 test for trends in proportions with α set to 0.05 and two-sided P values. All analyses were performed with the R Language and Environment for Statistical Computing version 2.9.0. Results: Included in the study were specimens of 4805 polypoid lesions from 8739 average risk screening colonoscopies. The rate of polyp detection per 100 screening colonoscopies was 24.0 (95% CI 23.2 to 24.7) for adenomas and 16.4 (95% CI 15.7 to 17.0) for serrated polyps. The detection rate of proximal serrated polyps, proximal sessile serrated adenomas, and both proximal and distal adenomas increased from 2006 to 2008 (Table). The difference in serrated polyp detection rates by year appeared to be mainly attributable to increased detection of proximal sessile serrated adenomas.Table: Table. Rate of detected polyps per 100 colonoscopies by year and locationConclusion: This study describes the detection rate of colorectal polyps in average risk screening colonoscopies at an urban academic medical center over a recent 3 year period. Practice personnel and technology were constant over this time. There was a statistically significant increase in the detection rate of proximal serrated polyps and both proximal and distal adenomas over the period. Increased awareness of the clinical significance of flat and sessile lesions including proximal hyperplastic polyps and sessile serrated adenomas may account in part for these findings.