Risk for lymph node metastasis in Epstein–Barr virus‐associated gastric carcinoma with submucosal invasion

Objectives Epstein–Barr virus‐associated gastric cancer (EBVGC) has been reported to be associated with a low risk for lymph node metastasis (LNM). However, the curative criteria for endoscopic submucosal dissection (ESD) for submucosal EBVGC (pT1b‐EBVGC) remain unclear. Our study aimed to investigate the risk factors for LNM in pT1b‐EBVGC. Methods This was a retrospective multicenter study at five institutes in Japan. We reviewed medical records and extracted all pT1b‐EBVGC cases that met the following criteria: (i) histologically proven submucosal gastric cancer; (ii) surgical or endoscopic resection between January 2000 and December 2016; and (iii) presence of Epstein–Barr virus (EBV) in tumor cells verified by EBV‐encoded small RNA in situ hybridization (EBER‐ISH). The association between clinicopathological factors and LNM were assessed using multivariable logistic regression analysis. Results A total of 185 pT1b‐EBVGC cases were included in the analysis. LNM was found in nine cases (4.9%). Multivariable logistic regression analysis demonstrated that lymphatic invasion (OR 9.1; 95% CI 2.1–46.1) and submucosal invasion ≥4000 μm (OR 9.2; 95% CI 1.3–110.3) were significant risk factors for LNM. When we focused on pT1b‐EBVGC without lymphatic invasion and with submucosal invasion <2000 μm, the rate of LNM was 0% (0/96, 95% CI 0–3.8%). Conclusions Our findings indicated that lymphatic invasion and submucosal invasion ≥4000 μm were significant risk factors for LNM. ESD could be an appropriate option for pT1b‐EBVGC without lymphatic invasion and with submucosal invasion <2000 μm.