Nationwide Multicenter Study of Advanced Endoscopic Resection and Malignant Risk Model for Gastric Myogenic Tumors (GASTRO Trial)

<b>Background/Objectives:</b> The prevalence of gastric subepithelial lesions (SELs) is rising. Endoscopic resection (ER) technique provides a minimally invasive alternative to manage gastric SELs. This study aims to evaluate the effectiveness and safety of ER for gastric myogenic tumors, and examine predictors for gastrointestinal stromal tumors (GISTs). <b>Methods:</b> The retrospective study was conducted between 2012 and 2024 at nine tertiary centers in Taiwan. We enrolled patients with endoscopic ultrasound (EUS)-documented gastric myogenic tumors managed by endoscopic muscular dissection (EMD), endoscopic subserosal dissection (ESSD), submucosal tunneling endoscopic resection (STER), and endoscopic full-thickness resection (EFTR). Clinical manifestation, endoscopic features, and outcomes were analyzed. <b>Results:</b> We enrolled 325 patients with 332 lesions [mean EUS size 14.5 mm, 153 (46.1%) leiomyoma, 152 (45.8%) GISTs, 27 (8.1%) other histology]. ER techniques were 193 (58.1%) EMD, 46 (13.9%) ESSD, 28 (8.4%) STER, and 65 (19.6%) EFTR. Technical success, en bloc, and R0 resection rates were 97.0%, 94.3%, and 88.9%, respectively. Twenty-four (9.0%) procedures were shifted to unintentional EFTR, and 21 (6.3%) patients had complications. No recurrence occurred during mean follow-up period of 921.4 days. Two (0.6%) patients died of non-procedure related reasons. Old age, fundus location, heterogeneous echotexture, and exophytic growth pattern were independent risk factors for GIST (all with <i>p</i> < 0.05). Using the above factors, we built a prediction model with sensitivity of 77.0%, specificity of 85.6%, and AUC of 0.8771. <b>Conclusions:</b> ER is an efficient and safe management for gastric myogenic tumors. The histological type could be predicted by demographic characteristics and EUS features.