Long-term oncological outcomes of submucosal manipulation during non-curative endoscopic submucosal dissection for submucosal invasive gastric cancer: a multicenter retrospective study in Japan

Background: Sufficient information is not available on the extent to which lymph node metastasis (LNM) and prognosis are affected by submucosal manipulation during endoscopic submucosal dissection (ESD) for submucosal invasive gastric cancer (SMGC). We aimed to identify the effects of submucosal manipulation during ESD on LNM and prognosis in patients with SMGC. Methods: From 19 institutions in Japan, 2526 patients who failed to meet the current curative criteria for ESD between 2000 and 2011 were recruited. After exclusion, 1969 patients were remained. Based on the treatment strategy after ESD, 1064 patients underwent additional radical surgery. A total of 890 of 1064 patients with SMGC, LNM and cancer recurrence, and prognosis were retrospectively reviewed. Results: The median follow-up duration was 67 months. A total of 214 patients had SM1 (depth of tumor invasion from the muscularis mucosae <500 μm) invasive cancer and 676 patients had SM2 (depth of tumor invasion from the muscularis mucosae ≥500 μm) invasive cancer. LNM was found in 84 patients (9.4%), and 14 patients (1.6%) developed cancer recurrence. The 3-year and 5-year overall survival rates were 96.1 and 91.7%, respectively. The 3-year and 5-year disease-specific survival rates were 99.3 and 98.5%, respectively. Conclusions: The rates of LNM and cancer recurrence, and prognosis of patients who underwent additional radical surgery after non-curative ESD for SMGC were excellent. Submucosal manipulation during ESD for SMGC does not seem to enhance the risk for LNM or worsen the prognosis compared to surgical series.