Long-term outcomes of endoscopic submucosal dissection versus surgery in early gastric cancer meeting expanded indication including undifferentiated-type tumors: a criteria-based analysis

Background Endoscopic submucosal dissection (ESD) for early gastric cancer (EGC) meeting the expanded indication is considered investigational. We aimed to compare long-term outcomes of ESD and surgery for EGC in the expanded indication based on each criterion. Methods This study included 1823 consecutive EGC patients meeting expanded indication conditions and treated at a tertiary referral center: 916 and 907 patients underwent surgery or ESD, respectively. The expanded indication included four discrete criteria: (I) intramucosal differentiated tumor, without ulcers, size > 2 cm; (II) intramucosal differentiated tumor, with ulcers, size <= 3 cm; (III) intramucosal undifferentiated tumor, without ulcers, size <= 2 cm; and (IV) submucosal invasion < 500 mu m (sm1), differentiated tumor, size <= 3 cm. We selected 522 patients in each group by propensity score matching and retrospectively evaluated each group. The primary outcome was overall survival (OS); the secondary outcomes were disease-specific survival (DSS), recurrence-free survival (RFS), and treatment-related complications. Results In all patients and subgroups meeting each criterion, OS and DSS were not significantly different between groups (OS and DSS, all patients: p = 0.354 and p = 0.930; criteria I: p = 0.558 and p = 0.688; criterion II: p = 1.000 and p = 1.000; criterion III: p = 0.750 and p = 0.799; and criterion IV: p = 0.599 and p = 0.871). RFS, in all patients and criterion I, was significantly shorter in the ESD group than in the surgery group (p < 0.001 and p < 0.003, respectively). The surgery group showed higher rates of late and severe treatment-related complications than the ESD group. Conclusions ESD may be an alternative treatment option to surgery for EGCs meeting expanded indications, including undifferentiated-type tumors.