239 Detection Rate of Serrated Adenomas in the Screening Colonoscopy Population

Abstract

INTRODUCTION: Colorectal cancers arise from 3 distinct pathways: the adenoma to carcinoma pathway, the Lynch syndrome pathway, and the serrated pathway. The serrated pathway is characterized by neoplastic transformation of serrated polyps, which are classified into hyperplastic polyps (HP), sessile serrated adenomas (SSA) and traditional serrated adenomas (TSA). HPs distal to descending colon have no malignant potential, while SSA & TSA are precancerous lesions. SSA are the major precursor lesions responsible of cancer via serrated pathway. SSA are difficult to differentiate histologically from HPs in the proximal colon. Recent studies have shown SSAs to be more common than previously believed. Our study purpose is to determine the prevalence of SSAs, variability amongst endoscopists in detecting serrated adenomas, and the identification of significant risk factors. METHODS: Patients undergoing screening colonoscopy were enrolled into this prospective cross-sectional study conducted at a tertiary community teaching hospital and an outpatient endoscopy unit. Screening colonoscopy was defined as the first colonoscopy performed in an asymptomatic patient without risk factors between the age of 50 and 80. Patients reported as having poor bowel preparation were excluded from the study. Statistical analysis was conducted to determine the overall detection rate of serrated adenomas and assess the variability among 6 endoscopists. RESULTS: Of the 263 screening colonoscopies, the serrated adenoma detection rate was 12.2% (95% CI 8.2–16.2%) with a wide range of variability amongst the 6 endoscopists from 3.4–15%. The total serrated polyp detection rate, which includes SSA, TSA and proximal HPs, was 13.7% (95% CI 9.5–17.9%) with a range of 10.2–17.5% amongst endoscopist. The adenoma detection rate for the endoscopists was 46.4% (95% CI 40.4–52.4%). Study results revealed serrated polyps have a significant association with Caucasians (P = 0.002), while adenomatous polyps are significantly associated with males (P = 0.001) and current smokers (P = 0.01). CONCLUSION: The increasing prevalence of SSA found in recent studies seems directly related to improving histologic distinction between SSA and HPs. Despite this improvement, the reported prevalence is still highly variable. Our study found that by using a total serrated polyp detection rate we were able to reduce variability amongst endoscopists, and a significant association between Caucasians and development of serrated polyps.