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COPENHAGEN — Cold snare endoscopic mucosal resection (CS-EMR) is safer than hot snare (HS)-EMR for the removal of large, non-pedunculated colorectal polyps, but the general recurrence rate after cold snare is higher, the first data from a prospective, multi-center, randomized controlled trial (RCT) show.

“The safety of cold snare EMR is superior to hot snare EMR with an almost complete elimination of major complications,” said Ingo Steinbrück, MD, sibutramine australia ban gastroenterologist from the Evangelisches Diakoniekrankenhaus Freiburg, Germany, who presented the findings at the United European Gastroenterology (UEG ) Week 2023.

“But because the general recurrence rate [residual neoplasia] is higher after cold snare, careful selection of the target lesion should be made,” he said. Based on the study findings, “cold snare EMR should be considered the new standard of care for suspected sessile serrated adenomas, laterally spreading tumors [LSTs] of non-granular type with no macroscopic signs of malignancy, and selected laterally spreading tumors of granular-type homogenous of 20 mm or more.”

In another abstract in the same session, presented by Óscar Nogales, MD,
gastroenterologist from the Hospital General Universitario Gregorio Marañón, Spain, the data showed that the recurrence rate of large non-pedunculated colonic lesions was significantly higher after CS-EMR, compared with the standard technique (conventional EMR), although there was also a trend toward fewer adverse effects.

First RCT of Cold vs Hot Snare EMR

Guidelines note that polyps of 10 mm or less should be removed by the cold snare technique, while those larger than 10 mm should undergo hot snare EMR, said Steinbrück. “However, recent data suggest cold snare might be beneficial in larger polyps of over 20 mm too, finding that there were no significant adverse events in the cold snare and residual adenoma rate was equal [to hot snare EMR]” he explained.

To investigate this further, he and his colleagues set about conducting a randomized controlled trial known as CHRONICLE (Cold vs. Hot snare Resection of Non-pedunculated polyps ≥ 2 cm in the Colorectum). “We hypothesized the superiority of cold snare in comparison with hot snare for the resection of non-pedunculated colorectal polyps of, or greater than, 20 mm,” he said.

A total of 399 participants across 19 German gastroenterology centers were randomly assigned to either the cold snare group (192 intent to treat), or the hot snare group (202 intent to treat). All had non-pedunculated polyps of 20 mm or more in the colorectum. Patients were followed up with a phone call at around 4 weeks after the procedure to check for complications, then with a first endoscopic follow-up at around 4 months, and a second at around 12 months.

Major adverse events including perforations and/or clinically significant post-endoscopic bleeding, comprised the primary endpoint. Secondary endpoints were intraprocedural bleeding, post-polypectomy syndrome, technical success, resection speed, and recurrence rate after 4 months.

Fewer Adverse Events, More Residual Neoplasia

“Lesions were mainly located in the right colon, mostly LSTs, granular type homogeneous, and a large amount were suspected sessile serrated lesions. The mean diameter was 3-8 cm, and the majority were adenomas with low grade dysplasia and sessile serrated lesions,” said Steinbrück.

The major adverse event rate was significantly lower in the cold snare compared with hot snare group at 1% vs 8%, respectively (P = .001), with perforations at 0% vs 4% (P = .007) and delayed bleeding at 1% vs 4.5% (P = .03) respectively, he reported. “This is a clear superiority [for CS-EMR].”

The rate of intraprocedural bleeding was also significantly lower in the cold snare patients compared with hot snare patients (14% vs 29.9% respectively; P = .02), but post-polypectomy syndrome was equal between groups, he added.

But the other part of the story is the effectiveness, Steinbrück continued. “Here, the picture is different.”

Of the 283 patients who were included in this analysis, residual neoplasia at the first endoscopic follow up was 24.8% in the cold snare group vs 15% in the hot snare group (P = .037). “These are preliminary data, but I think the message is clear in that the rate of residual neoplasms is higher in the cold snare group,” said Steinbrück.

Technical success rate was also lower in the cold snare than in the hot snare groups at 92.2% compared with 97.5% respectively (P = .02).

Upon subgroup analyses, the researchers found that suspected sessile serrated lesions were good candidates for cold snare because residual neoplasia were equal in cold and hot snare procedures at around 5% each. LST nodular-mixed type lesions were considered unsuitable for cold snare EMR due to a much higher rate of residual neoplasia than hot snare EMR at 43.8% vs 16.7% respectively (P = .01). And selected lesions in LST granular type homogeneous and LST non-granular type might be candidates due to less clear differences in results, Steinbrück added.

Cold Snare EMR vs Conventional EMR

The second abstract compared the efficacy of complete resection between cold snare and conventional EMR in large non-pedunculated colonic lesions, measuring absence of recurrence at 6 months. The non-blinded RCT was carried out across 15 hospitals in Spain and involved consecutive, non-pedunculated lesions with adenoma or serrated histology, homogeneous type, with size 20 mm or more. A total of 229 patients (mean age, 68 years) were included. Median lesion size was 25 mm (predominantly adenomas), and nearly 79% of the lesions were found in the proximal colon.

Nogales reported that the recurrence rate was significantly higher in the cold snare group compared with the conventional EMR group at 33.6% vs 16.7%, respectively (P  = .007).

“Colonic lesions larger than 30 mm diameter were more prone to recurrence,” he reported, with recurrence rates of 44% and 19% in cold snare and conventional EMR respectively (P = .05). “Also, in serrated lesions in particular, the recurrence rate was higher in cold snare vs conventional EMR at 34.4% compared with 4.2%.” The rates were similar in adenomas.

“Adverse events were low overall, with no differences between groups and a slight tendency towards more complications in the conventional EMR patients,” said Nogales. En bloc and R0 resection rates were higher in the conventional arm, as were the use of clips for the closure of mucosal defects, “but numbers were low so take [the results] with caution,” he added. 

Selection of Right Lesion Is “Key”

Session co-moderators Nastazja Pilonis, MD, from the Department of Oncological Gastroenterology, Maria Sklodowska-Curie Institute of Oncology, Warsaw, Poland, and Marco Spadaccini, MD, from the Biomedical Science, Humanitas University, Milan, Italy, commented on the study results in a joint interview with Medscape Medical News.

With reference to the cold vs hot snare EMR techniques, Pilonis remarked, “I think recurrence is the price we have to pay for the lower event rate, but overall, I think these data provide great evidence.”

“Every new technique often looks like a game-changer, but despite the appeal, we need to recognize that there are some significant limitations,” she pointed out. “We need to choose the right lesions that are the best candidates for these techniques. If a patient is compliant with the next surveillance colonoscopy, then that’s the way to go, but if we felt we might not see them again, then we might reconsider using the cold snare technique.”

Spadaccini concurred, saying that selecting the right lesion to go cold is key, as is choosing those where recurrence risk is lower. “Most residual neoplasia are relatively easy to remove during endoscopy, but the problem is usually having the opportunity of seeing the patient again as well as finding the recurrence,” he added.

Steinbrück declares lecture fees and travel funds from Olympus Medical and Falk Pharma. Nogales, Pilonis, and Spadaccini report no relevant financial relationships.

United European Gastroenterology (UEG) Week 2023: Abstract LB06. Presented October 16, 2023.

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