The 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 5 institutes in Japan. We reviewed medical records and extracted all pT1b-EBVGC cases that met the following criteria; 1) histologically proven submucosal gastric cancer, 2) surgical or endoscopic resection between January 2000 and December 2016, and 3) presence of 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 9 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.