Long-term outcomes after non-curative endoscopic submucosal dissection for early gastric cancer according to hospital volumes in Japan: a multicenter propensity-matched analysis

Background: There is a lack of data regarding the long-term outcomes of endoscopic submucosal dissection (ESD) for early gastric cancer (EGC) without curative resection, and the relationship of these outcomes with hospital volumes remains unclear. This study evaluated long-term outcomes of patients who underwent ESD for EGC without curative resection according to hospital volumes in Japan. Methods: This multicenter retrospective study evaluated 1,969 patients who did not meet the criteria of the Japanese Gastric Cancer Association for curative resection between January 2000 and August 2011. Hospitals were classified according to the annual number of ESD procedures: low- and medium-volume group (LMVG), high-volume group (HVG), and very high-volume group (VHVG). Clinicopathological features, overall survival (OS), disease-specific survival (DSS), and recurrence-free survival (RFS) were compared across groups after a generalized propensity score matching analysis. Results: In 495 pairs of generalized propensity score-matched patients, the 5-year OS, DSS, and RFS rates were 81.5%, 97.9%, and 97.6% for LMVG; 86.9%, 98.2%, and 97.0% for HVG; and 85.4%, 98.5%, and 97.6% for VHVG, respectively. The 5-year DSS and RFS rates did not significantly differ among the three groups. However, 5-year OS was significantly worse in the LMVG than in the HVG and VHVG (P < 0.001 and P = 0.008, respectively). Conclusions: DSS and RFS in patients with EGC who did not meet the criteria for curative resection did not differ across hospital volumes in Japan. Even in cases in which ESD for EGC involved non-curative resection, the procedure is feasible across Japanese hospitals with different volumes.