Clinicopathological features of Epstein–Barr virus associated gastric carcinoma with submucosal invasion.

Abstract

4029 Background: The incidence of lymph node metastasis (LNM) in pathological T1b (pT1b) gastric cancer (GC) is around 20% and the majority of them have no LNM. The Cancer Genome Atlas Research Network proposed the concept of molecular phenotype classifying GC into 4 phenotypes including Epstein-Barr virus-CIMP (EBV). EBV positive gastric cancer (EBVGC) is associated with a low prevalence of LNM; however, EBV status is not considered in the present indication of endoscopic resection (ER). We aimed to clarify the implication of EBV status for ER of pT1b GC. Methods: Consecutive cases of pT1b GCs treated with curative surgery between 2005 and 2014 were retrospectively analyzed. Tissue microarray was made and EBV-encoded RNA in situ hybridization was performed for evaluation of EBV status. Clinicopathological factors and LNM status were compared between EBVGC and non-EBVGC groups. Results: Among the 1221 pT1b GCs that underwent gastrectomy with regional lymph node dissection, 898 pT1bGCs were eligible in this study. EBVGC accounted for 7.9% (71 of 898) cases. Compared to non-EBVGC, EBVGC was more frequent in males (p = 0.0055), the upper third region (p < 0.0001), showed elevated growth features (p = 0.0059), and was associated with a lower frequency of accompanying ulceration (p = 0.002), greater depth of submucosal invasion (p = 0.017), and lower frequency of lymphatic invasion (p < 0.0001). Frequency of LNM was significantly lower in EBVGC than in non-EBVGC (4.2% vs. 21.9%, p < 0.0001). In EBVGC, tumors without lymphovascular invasion showed significantly lower frequency of LNM than those with lymphovascular invasion (0 of 50, 0%; vs 3 of 21, 14.3%; p = 0.023). Histologically, 84.5% (60 of 71) of EBVGC included carcinomas with lymphoid stroma and/or lace pattern components. Conclusions: pT1b EBVGC is a convincing candidate for ER, regardless of risk factors other than lymphovascular invasion.