Dual-modality management of non-lifting colorectal neoplasia: CAST or ACA?

We read with great interest the article by Tate et al. on cold-forceps avulsion with adjuvant snare-tip soft coagulation (CAST) for non-lifting portions of laterally spreading lesions [1]. In spite of an impressive 98.9 % surgery-sparing rate following CAST, deep mural injuries were reported relatively frequently, with an intraprocedural perforation rate of up to 5.3 % and a need for clip application in up to 23.7 % of procedures.

We previously described a similar dual-modality ablation/avulsion method to treat benign non-lifting fibrotic polyps (ablation with cold avulsion [ACA]), which showed good results and no reported perforation or need for clip application [2]. A key difference is that ACA delivers thermal energy first to soften and diathermize the adherent polyp tissue, followed by gentle mechanical separation using standard biopsy forceps of the charred surface layer from the underlying fibrotic tissue ([Fig. 1]). CAST relies on forceful pulling on adherent polyp tissue, which can lead to unpredictable tearing and separation of the underlying muscle layer, as well as to bleeding that obscures the endoscopic view.

Fig. 1 Endoscopic views of the ablation with cold avulsion (ACA) procedure showing: a a 15-mm recurrent laterally spreading lesion alongside the ileocecal valve; b the fibrotic base after ablation with argon plasma coagulation; c the appearance after avulsion with biopsy forceps; d a healed scar that is free of recurrence at follow-up.

In addition, ACA uses argon plasma coagulation as the thermal modality. This gives a superficial [3] [4] and controlled non-contact diathermy effect that rarely causes bleeding and can rapidly treat even a large area of fibrotic polyp tissue. The sequence of ablation followed by avulsion in ACA can be repeated until all polyp tissue has been “peeled away,” often leaving a white visible scar below.

Finally, it is important to emphasize that both CAST and ACA require careful optical assessment [5], with or without standard biopsies, to avoid ablative treatment of invasive tumors that would necessitate more invasive techniques, such as endoscopic submucosal dissection or surgery, for cure.

• 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 ZP, 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 (Suppl. 01) E248-E249
• 3 Burgess NG, Bahin FF, Pellise M. et al. Argon plasma coagulation compared with snare tip soft coagulation in an in-vivo porcine model of endoscopic mucosal resection. Gastrointest Endosc 2015; 81: AB269
• 4 Watson JP, Bennett MK, Griffin SM. et al. The tissue effect of argon plasma coagulation on esophageal and gastric mucosa. Gastrointest Endosc 2000; 52: 342-345
• 5 Backes Y, Moss A, Reitsma JB. et al. Narrow band imaging, magnifying chromoendoscopy, and gross morphological features for the optical diagnosis of T1 colorectal cancer and deep submucosal invasion: A systematic review and meta-analysis. Am J Gastroenterol 2017; 112: 54-64