S0973 Outcomes of en-bloc vs Piecemeal Endoscopic Resection for Colorectal Polyps With High-Grade Dysplasia or Intramucosal Cancer

Abstract

INTRODUCTION: Benign colorectal polyps with high grade dysplasia (HGD) or intramucosal cancer (ImCA) are often large and can be completely removed by endoscopic resection (ER). However, malignant recurrence after ER of HGD/ImCA has been described in Asian literature, which is of significant concern. Also, it is uncertain whether type of ER (piecemeal vs. en-bloc) for HGD/ImCA impacts clinical outcomes. We evaluated the short- and long-term outcomes of endoscopic resection of colorectal polyps with HGD/ImCA. METHODS: Retrospective chart review was performed to identify patients who underwent ER for colorectal polyps with HGD/ImCA in two academic medical centers from 2005 to 2019. Clinical, endoscopic, and pathological characteristics of all patients were extracted. To adjust for potential censoring bias, Competing-Risk Regression was performed to estimate the benign recurrence as malignant lesions were counted as a competing risk due to surgical referrals with no follow-up procedures. RESULTS: A total of 196 patients with HGD/ImCA lesions were included; 66 (33.6%) were resected en bloc and 130 (66.3%) piecemeal. Polyps resected by piecemeal ER (p-ER) were larger in size (22.8 vs. 15.1 mm, P < 0.0001), sessile in morphology (P < 0.0001), and right-sided in location (P < 0.0001) compared to en-bloc [Table 1]. 17 (8.6%) patients were referred for surgery after index colonoscopy, all after p-ER. Adverse events occurred in 4 patients (3 delayed bleeding and 1 post polypectomy syndrome). 126 (64%) patients entered surveillance colonoscopy. A total of 31 recurrences occurred over a mean follow-up period of 21 months. Benign recurrences were 11 times (HR = 10.8, 95% CI: 1.5–78.9; P = 0.019) more likely in p-ER than en-bloc group [Figure 1A]. HGD/malignant recurrence occurred in 4/31 patients, all among p-ER (log-rank P = 0.132) with the number needed to treat to prevent 1 malignant recurrence 4.9 (95% CI 2.8–19.2) [Figure 1B]. All these patients were referred for surgery. 26/31 (84%) underwent repeat ER. Of these, 8/26 (30.7%) had successful ER without any further recurrence, and 5/26 (19%) still had residual adenoma despite repeated ER attempts after a mean of 1.9 ± 0.79 procedures, and 2/26 died of unrelated reasons. CONCLUSION: Piecemeal resection of polyps with HGD/ImCA resulted in higher proportion of malignant recurrence and surgical referral compared to en-bloc resection. Thus, en-bloc resection should be preferred for these lesions whenever technically feasible.Table 1.: Baseline characteristics for all included patientsFigure 1.: A: Risk of adenoma recurrence. B: Risk of advanced adenoma and malignant recurrence.