Journal Club

Paper discussion: Endoscopic mucosal resection combined with hybrid argon plasma coagulation to prevent recurrence of large nonpedunculated colorectal polyps (Motchum et al GIE 2022) https://giejournal.org/retrieve/pii/S0016510722017692)

In contrast to Japan, Korea and other Eastern countries, endoscopic mucosal dissection (EMR) is considered to be the standard of care for resecting colorectal non-polypoid lesions larger than 20 mm in most Western countries. Unfortunately, EMR, especially piecemal-EMR, is associated with high post-resection recurrence rates of up to 21% (1-4). Argon plasma coagulation (APC) has been shown to reduce recurrence rates after piecemeal EMR. A novel ablative method, hybrid APC (h-APC) encompasses submucosal injection and application of APC. The hope being that submucosal injection is going to prevent perforation when applying APC.

In a two-center, prospective case series Motchum et al enrolled 84 patients with 101 non-polypoid lesions larger than 20 mm during a 2-year period (5). The lesions measuring a median of 30 mm (range 20 to 60 mm) were resected using piecemal EMR and afterwards treated with h-APC. Patients were scheduled for follow-up colonoscopy at 4-6 months after the intervention. The authors found that the recurrence rate was 2.2%, with 13% complications, of which almost a third were severe (n = 4 patients, 3.6%) (5). An additional patient had a perforation during index EMR and was excluded from the study.

This data is quite encouraging and the efficacy almost matches that of endoscopic submucosal dissection. Although one could be encouraged to add h-APC to the armamentarium of techniques to decrease post-EMR polyp recurrence, it is important to recognize that the study has several potential drawbacks.

• First it was non-controlled, non-randomized. Ideally, this new method should have been compared to an established technique such as STSC (6).

• Second, the study was non-standardized. It was left at the discretion of the endoscopist how to apply h-APC. Some endoscopists applied APC at the borders and base and others just at the borders. The definition of border was also unclear, as it was defined an area extending 3 to 5 mm beyond the resection line. Furthermore, a total of seven different snares from three different manufacturers were used, ranging from 10 mm to 27 mm in diameter.

• Third, lots of patients were lost to follow-up (n=7).

• Fourth, the settings (0,8 liters flow, 40 W, effect 2) appeared somewhat “stiff”, as only this one setting was used for right and left colon lesions. In the study there were more than 85% of lesions coming from the proximal colon. But what about this large laterally-spreading tumors located in the distal colon, and especially the rectum. Do these settings suffice to ablate the remaining tumoral tissue?

• And fifth, on follow-up only 74 out of 84 patients underwent biopsy of the resection site. This may overestimate the “efficacy” rate of h-APC.

In sum, this open-label, two-center case series showed that h-APC is feasible and appears to have promising efficacy in decreasing polyp resection after piecemeal EMR. But this study also underscores the fact that traditional piecemeal EMR is an insufficient technique to completely resect colorectal polyps larger than 20 mm. Otherwise we would not need to continue evaluating ablative techniques to deal with neoplastic tissue left-overs (R1 or incomplete resection).