Advantages of CAST for non-lifting adenomas

We would like to thank the authors for their kind reflection on our manuscript.

There are predominantly three techniques described for the management of non-lifting adenoma at endoscopic mucosal resection (EMR): cold avulsion with subsequent (adjuvant) snare-tip soft coagulation (CAST) [1], initial argon plasma coagulation (APC) ablation of non-lifting tissue and subsequent avulsion [2], and hot forceps avulsion [3]. We believe CAST has significant advantages over the other described techniques.

The authors highlight the important need for meticulous lesion inspection prior to the application of these techniques. This comment highlights a major advantage of CAST – all tissue is reliably retrieved for histopathological analysis. With ablation of visible adenoma prior to tissue retrieval, there is always a significant risk of incompletely ablating invasive disease that is therefore unrecognized, and which may present with disseminated disease at later follow-up.

Other advantages of the CAST technique are the precision of the technique and the cost-effectiveness of using the same snare that is used for the resection. Whilst no difference in the depth of tissue injury between the techniques has been shown in an animal model [4], APC is anecdotally more unpredictable to apply, in addition to there being a high cost for the consumables.

It is important to emphasize that the 101 non-lifting lesions described in our study were the most difficult 16 % of lesions that presented to our center over the study period and that, without CAST, they would otherwise have required surgical resection. Importantly, the rate of intraprocedural perforation was not significantly different in the consecutive lesions resected using CAST when compared to the naïve lifting group resected using standard snare resection.

The high rate of endoscopic clip application in this study reflects our previous observation that Sydney type II deep mural injury, often found in lesions requiring CAST because of the associated submucosal fibrosis that precludes snare resection, is a risk factor for delayed perforation [5]. Circumstantial evidence in the described study [1] suggests that this is sensible, given that the only delayed perforation in the entire cohort occurred in a patient with a lifting laterally spreading lesion resected using standard snare resection without CAST.

• References

• 1 Tate DJ, Bahin FF, Desomer L. et al. Cold-forceps avulsion with adjuvant snare-tip soft coagulation (CAST) is an effective and safe strategy for the management of non-lifting large laterally spreading colonic lesions. Endoscopy 2018; 50: 52-62
• 2 Tsiamoulos Z, Rameshshanker R, Gupta S. et al. Augmented endoscopic resection for fibrotic or recurrent colonic polyps using an ablation and cold avulsion technique. Endoscopy 2016; 48: E248-E249
• 3 Veerappan SG, Ormonde D, Yusoff IF. et al. Hot avulsion: a modification of an existing technique for management of nonlifting areas of a polyp (with video). Gastrointest Endosc 2014; 80: 884-888
• 4 Burgess NG, Bahin FF, Pellise M. et al. Sa1580 argon plasma coagulation compared with snare tip soft coagulation in an in-vivo porcine model of endoscopic mucosal resection. Gastrointest Endosc 2015; 81: AB269
• 5 Burgess NG, Bassan MS, McLeod D. et al. Deep mural injury and perforation after colonic endoscopic mucosal resection: a new classification and analysis of risk factors. Gut 2017; 66: 1779-1789