Serrated Lesions of the Colorectum: Review and Recommendations From an Expert Panel

TLDR

Serrated colorectal lesions, including hyperplastic polyps, sessile serrated adenomas/polyps, and traditional serrated adenomas, account for about one‑third of colorectal cancers, most arising in the proximal colon, and are more difficult to detect endoscopically than conventional adenomas. The authors aimed to provide evidence‑based guidance for the clinical management of serrated colorectal lesions, covering definitions, classification, and clinical significance. A two‑day consensus conference reviewed serrated lesions from histology, molecular biology, epidemiology, clinical aspects, and serrated polyposis perspectives. The panel recommends that endoscopists be trained to recognize serrated lesions, that all lesions proximal to the sigmoid colon and rectosigmoid lesions >5 mm be completely removed, and that specific post‑polypectomy and serrated polyposis surveillance protocols be followed.

Abstract

Serrated lesions of the colorectum are the precursors of perhaps one-third of colorectal cancers (CRCs). Cancers arising in serrated lesions are usually in the proximal colon, and account for a disproportionate fraction of cancer identified after colonoscopy. We sought to provide guidance for the clinical management of serrated colorectal lesions based on current evidence and expert opinion regarding definitions, classification, and significance of serrated lesions. A consensus conference was held over 2 days reviewing the topic of serrated lesions from the perspectives of histology, molecular biology, epidemiology, clinical aspects, and serrated polyposis. Serrated lesions should be classified pathologically according to the World Health Organization criteria as hyperplastic polyp, sessile serrated adenoma/polyp (SSA/P) with or without cytological dysplasia, or traditional serrated adenoma (TSA). SSA/P and TSA are premalignant lesions, but SSA/P is the principal serrated precursor of CRCs. Serrated lesions have a distinct endoscopic appearance, and several lines of evidence suggest that on average they are more difficult to detect than conventional adenomatous polyps. Effective colonoscopy requires an endoscopist trained in the endoscopic appearance of serrated lesions. We recommend that all serrated lesions proximal to the sigmoid colon and all serrated lesions in the rectosigmoid > 5 mm in size, be completely removed. Recommendations are made for post-polypectomy surveillance of serrated lesions and for surveillance of serrated polyposis patients and their relatives.