Recurrence with malignancy after endoscopic resection of large colon polyps with high-grade dysplasia: incidence and risk factors.

Background: In the West, piecemeal endoscopic resection remains the primary treatment for large colon polyps (LCP), as most recurrences are believed to be benign and resectable with follow-up endoscopy. However, invasive malignancy at the site of prior piecemeal endoscopic mucosal resection has been reported in the Asian literature. This study aims to identify the incidence of and the risk factors for local recurrence with malignancy after endoscopic resection of LCP with high-grade dysplasia (HGD).

Methods: In this retrospective cohort study, we identified patients undergoing complete endoscopic resection of LCPs (≥ 20 mm) with HGD at the Cleveland Clinic between January 2000 and December 2016. Demographic, endoscopic, and pathologic data were collected. All subsequent endoscopic and pathology reports were reviewed to identify recurrence. The cumulative incidence of malignancy at the polypectomy site was determined and univariate analysis was performed to assess risk factors.

Results: A total of 254 LCPs with HGD were resected in 229 patients. Mean polyp size was 29.2 mm. There were 138 lesions resected in piecemeal fashion and 116 en-bloc. After a median follow-up of 28.7 months for the entire cohort, local recurrence with malignancy was diagnosed in six cases. Median time to malignancy diagnosis was 28.5 months. All malignant cases occurred after piecemeal resection and none after en-bloc resection (HR 11.4; 95% CI 0.48-273).

Conclusion: Malignancy after endoscopic resection of LCPs with HGD is uncommon and may be associated with piecemeal resection. When possible, en-bloc resection should be the goal for the management of LCPs.