Does the double-opening submucosal tunneling endoscopic resection technique really work for submucosal tumors in the esophagus and gastric fundus near the cardia?

We read with great interest the article by Zhang et al., who carried out a preliminary evaluation of the feasibility and safety of submucosal tunneling endoscopic resection (STER) with a double opening (DO-STER) [1]. In this study, the modified technique of DO-STER was applied on the basis of two considerations. One was the limited tunnel space that affects the endoscopic resection of large tumors in the esophagus. The other was that, for large tumors in the esophagogastric junction (EGJ) and the gastric fundus near the cardia, it is difficult to dissect the submucosal layer over the tumor to form the submucosal tunnel operating space on the distal side of the tumor. Resection of 10 submucosal tumors (SMTs) was attempted using DO-STER, of which 9 were resected en bloc and 1 was resected in two pieces without postoperative complications. Therefore, the seemingly encouraging results in this study led to the conclusion that DO-STER seems to provide an alternative approach for resection of tumors in the esophagus and gastric fundus near the cardia.

However, we have concerns about the appropriateness of DO-STER. Firstly, Zhang et al included 10 SMTs, with sizes ranging from 1.0 × 1.2 cm to 3.5 × 5.0 cm. There were three SMTs of relatively small size at the EGJ, namely 1.0 × 2.0 cm, 1.0 × 1.2 cm, and 1.0 × 2.0 cm. These might not have been included if the selection criteria of the study had allowed large tumors only, although there is no specific definition in the literature of the term “large tumor.” Employing the DO-STER technique for these three tumors entailed larger wounds and the cost of treatment might also have been greater, imposing an unwanted economic burden on patients.

Secondly, the tumor diameters were not distinctly described in the study. According to Chen et al., the maximal inner diameter of the tunnel is about 3.0 – 4.0 cm. Thus, the transverse diameter of the SMTs treated by STER cannot be more than the inner diameter of the tunnel (approximately 3.5 cm), but the length, can be up to 7.0 cm [2]. A previous study has shown the en bloc resection rate for SMTs in the upper gastrointestinal (GI) tract to be 97.6 % [3]. Therefore a high rate of en bloc resection of SMTs can be accomplished by STER. Was the high en bloc resection rate of 90 % in this study achieved because of the effectiveness of DO-STER or because tumor diameters were less than 3.5 cm?

In addition, according to our own study, the en bloc resection rate for SMTs in the EGJ was 74.5 %, and irregular shape was one of the reliable risk factors for failure of en bloc resection [4]. In the study by Zhang et al., one out of four tumors in the EGJ, being of size 1.5 × 2.5 cm, was resected in two pieces. This result was comparable to those of our study.

In summary, the modified technique provides an innovative concept for managing large SMTs in the upper GI tract. However, the indefinite description of the basic characteristics of the tumors and the selection criteria in this study weaken the argument for DO-STER. Further studies are warranted to elucidate the indications and feasibility regarding DO-STER.

• References

• 1 Zhang Q, Cai JQ, Xiang L. et al. Modified submucosal tunneling endoscopic resection for submucosal tumors in the esophagus and gastric fundus near the cardia. Endoscopy 2017; 49: 784-791
• 2 Chen T, Zhang C, Yao LQ. et al. Management of the complications of submucosal tunneling endoscopic resection for upper gastrointestinal submucosal tumors. Endoscopy 2016; 48: 149-155
• 3 Wang H, Tan Y, Zhou Y. et al. Submucosal tunneling endoscopic resection for upper gastrointestinal submucosal tumors originating from the muscularis propria layer. Eur J Gastroenterol Hepatol 2015; 27: 776-780
• 4 Li Z, Gao Y, Chai N. et al. Effect of submucosal tunneling endoscopic resection for submucosal tumors at esophagogastric junction and risk factors for failure of en bloc resection. Surg Endosc 15.08.2017; DOI: 10.1007/s00464-017-5810-8. [Epub ahead of print]