Supplementary Material for: Comparison of Safety and Outcomes between Endoscopic and Surgical Resections of Intermediate-risk Primary Gastric Gastrointestinal Stromal Tumors

The objective of this study was to compare the safety and efficacy of endoscopic resection with surgical resection in the treatment of intermediate-risk gastric GISTs, and to further evaluate whether imatinib adjuvant treatment is necessary for resected intermediate-risk gastric GIST by ER. Methods: We retrospectively studied 128 cases for intermediate-risk gastric GISTs that were distributed in endoscopic (n=33) and surgical groups (n=95) at our center between December 2009 to July 2020. We statistically compared the clinical features, pathological reports, perioperative data, and long-term follow-up outcomes. Results: Compared with the surgery group, the endoscopy group was associated with smaller tumor size (2.4±1.0 vs 6.0±1.7cm, P<0.001), shorter operating time (67.3 ±36.5 vs 145.9±74.8min, P<0.001), fewer incidence of short term post-operative complications (3% vs 32.6%, P=0.002). Shorter post-operative hospital days (4.5±1.4 vs 8.5±2.4d, P<0.001), shorter gastric functional recovery time (P<0.001) and a lower overall medical cost of hospitalization (P<0.001) was detected in the endoscopy group. During the median 44.5 months follow-up period , there were no cases of recurrence, metastasis, and death in the endoscopy group. Among 128 patients, 68 accepted adjuvant therapy with imatinib after resection. It was observed that the OS of the adjuvant treatment group with imatinib was lower than that of the group without imatinib (P=0.033). Conclusions: Endoscopic resection for intermediate-risk gastric GIST is a feasible and safe method. And there is no significant benefit for patients with intermediate-risk gastric GIST to accept imatinib adjuvant treatment after ER.