Endoscopic full‐thickness resection for gastric submucosal tumors: Japanese multicenter prospective study

Objectives Early gastric cancer endoscopic resection (ER) is prominent in Japan. However, evidence regarding ER of gastric submucosal tumors (SMT) is limited. This prospective multicenter phase II study investigated the efficacy and safety of endoscopic full‐thickness resection (EFTR) for gastric SMT. Methods Endoscopic full‐thickness resection indication for gastric SMT was 11–30 mm, histologically proven or clinically suspicious (irregular margin, increasing size, or internal heterogeneity) gastrointestinal stromal tumors (GIST), with no ulceration and intraluminal growth type. The primary end‐point was the complete ER (ER0) rate, with a sample size of 42. Results We enrolled 46 patients with 46 lesions between September 2020 and May 2023 at seven Japanese institutions. The mean ± SD (range) endoscopic tumor size was 18.8 ± 4.5 (11–28) mm. The tumor resection and defect closure times were 54 ± 26 (22–125) min and 33 ± 28 (12–186) min, respectively. A 100% ER0 was achieved in all 46 patients. The EFTR procedure was accomplished in all patients without surgical intervention. One patient had delayed perforation and was managed endoscopically. GIST accounted for 76% ( n = 35) of the cases. R0, R1, and RX rates were 33 (77%), 3 (6.5%), and 7 (15%), respectively. Conclusion Endoscopic full‐thickness resection for gastric SMT of 11–30 mm is efficacious. It warrants further validation in a large‐scale cohort study to determine the long‐term outcome of this treatment for patients with gastric GIST.