Potential for expanding indications and curability criteria of endoscopic resection for early gastric cancer in elderly patients: results from a Japanese multicenter prospective cohort study

Background and Aims: Evidence for endoscopic resection (ER) in elderly patients with early gastric cancer (EGC) is limited. We assessed its clinical outcomes and explored new indications and curability criteria. Methods: We analyzed data from a Japanese multicenter, prospective cohort study. Patients aged >= 75 years with EGC treated with ER were included. We classified eCuraC-2 (corresponding to noncurative ER, defined in the Japanese gastric cancer treatment guidelines) into elderly-high (>10% estimated metastatic risk) and elderly-low (ELL) (<= 10% estimated metastatic risk). Results: In total, 3371 patients with 3821 EGCs were included; endoscopic submucosal dissection was the prominent treatment choice. Among them, 3586 lesions met the guidelines' ER indications, and 235 did not. The proportions of en bloc and R0 resections and perforations were 98.9%, 94.4%, and 0.8%, respectively, in EGCs within the indications. In EGCs beyond the indications, they were 99.5%, 85.4%, and 5.9%, respectively, for lesions diagnosed as <= 3 cm and 96.0%, 64.0%, and 18.0%, respectively, for those >3 cm. Curative ER and EL-L were observed in 83.6% and 6.2% of lesions within the indications, respectively, and in 44.2% and 16.8% of lesions <3 cm beyond the indications, respectively. The 5-year cumulative gastric cancer death rates after curative ER and elderly-high were 0.3% (95% confidence interval [CI], 0.2-0.6) and 3.5% (95% CI, 2.0-5.7), respectively. After EL-L, the rate was 0.9% (95% CI, 0.2-3.5) even without subsequent treatment. Conclusions: The usefulness of endoscopic submucosal dissection for elderly EGC patients was confirmed by their clinical outcomes. Lesions of <= 3 cm and EL-L emerged as new ER indication and curability criteria, respectively.