Recurrence rate during long-term follow up after cold and hot resection of large non-pedunculated polyps in the colorectum – results from the multicentric, randomized controlled CHRONICLE-trial

Aims As shown recently in two randomized controlled trials, cold resection of non-pedunculated colorectal polyps≥20 mm appears to be significantly safer than endoscopic mucosal resection (EMR) with the hot snare, but at the cost of a higher rate of residual adenoma at first follow-up (FU) endoscopy [1] [2]. Since guidelines recommend FU endoscopy within 6 months after piecemeal-EMR, with subsequent endoscopic resection of residual adenoma [3], we hypothesize that the significantly higher rate of residual adenoma after cold snare-EMR of 23.7% vs. 13.8% in the CHRONICLE-trial¹ should become similar in the long term for both resection techniques. Thus, the higher rate of residual adenoma after cold snare resection at first FU may be of less clinical relevance. We therefore performed a comparative analysis of the long-term FU data from the CHRONICLE trial.

Methods Comparative study of 4- and 12-month FU data from the prospective, randomized CHRONICLE trial. Primary endpoint for this analysis was the rate of residual adenoma at the second endoscopic FU.

Results Between 2021 and 2023 396 polyps in 363 patients (48.2% female) had been enrolled in this study. Data on first FU examination were available in 92.2% of the previously resected polyps. In the intention-to-treat dataset the rate of residual adenoma was 18.6% (68/365), followed by endoscopic re-resection in 62 (91.2%) cases (polypectomy/EMR in 35, Endoscopic full thickness resection (EFTR) in 5 and forceps resection in 22 cases). 6 cases (8.8%) were transferred for surgical treatment. Data on second FU endoscopy were currently available for 268 polyps (67.7%). The rate of residual adenoma was 13.6% (18/132; 95%-CI: 8,2-19,7%) in the cold and 10.3% (14/136; 95%-CI: 5,2-15,4%) in the hot EMR group (p=0.399). All but one case in the hot EMR group that underwent surgery were re-retreated endoscopically (polypectomy/EMR in 15, EFTR in 5 and forceps resection in 11 cases).

Conclusions Rates of residual adenoma at the second FU (after retreatment of recurrent neoplasia at the first FU endoscopy) were still high around 10%, but similar in both groups. Thus, the disadvantage of cold EMR with regards to recurrence was less relevant at this stage. Assuming good patient compliance, cold snare EMR with subsequent resection of residual adenoma in the first FU endoscopy may be considered for benign, large, non-pedunculated colorectal polyps. Efforts to reduce rates of residual/recurrent neoplasia (like margin coagulation) have to be intensified.

• References

• 1 Ferlitsch M, Moss A, Bisshops R. et al. Colorectal polypectomy and endoscopic mucosal resection: European Society of Gastrointestinal Endoscopy (ESGE) Guideline – Update 2024. Endoscopy 2024; 56 (07): 516-545
• 2 Schmiegel W, Buchberger B, Follmann M. et al. S3-Leitlinie Kolorektales Karzinom. Z Gastroenterol 2017; 55 (12): 1344-1498
• 3 O´Sullivan T, Cronin O, van Hattem WA. et al. Cold versus hot snare endoscopic mucosal resection for large (≥ 15 mm) flat non-pedunculated colorectal polyps: a randomised controlled trial. Gut 2024; 73 (11): 1823-1830