Incidence rate and clinic-pathologic features of EBV-associated gastric carcinoma in China.

Abstract

e16048 Background: Nine percent of tumors in the TCGA study were assigned to be EBV-associated gastric carcinoma (EBVaGC). Previous reports on EBVaGC were small sample size studies. Methods: From July 1, 2014 to February 10, 2018, we prospectively detected EBER status in 2760 gastric adenocarcinoma patients from Sun Yat-sen University Cancer Center. DNA from plasma samples was extracted using the Qiamp Blood Kit (Qiagen, Hilden, Germany). EBV-DNA load was measured by real-time quantitative PCR. The cut-off value for positive EBV-DNA was set as 1000 copy/ml. Results: The incidence rate of EBVaGC in our cohort was 5.07% (140/2760). Compared with EBV-negative gastric carcinoma (EBVnGC), EBVaGC were younger and male predominance, preferential Lauren diffuse subtype, less HER2 positive, earlier T and N stage, less distant metastasis. The survival data need longer time to follow up. The HP infection rate was not significant difference between EBVaGC (15.0%) and EBVnGC (16.03%) patients, P = 0.851. Among the 2760 patients, there were 69 patients had paired biopsy and surgical resection samples. The consistent rate between biopsy and surgical resection samples was 98.6% (68/69). Only 1 patient was EBER negative in the biopsy and positive in the resection sample. The mean concentration of plasma EBV DNA in EBVaGC and EBVnGC patients were 11007.6 copy/ml and 162.8 copy/ml respectively. When we set 1000 copy/ml as cutoff value, the positive rate of EBV DNA in EBVaGC and EBVnGC patients were 25.71% and 1.87% respectively. We monitored the change of plasma EBV-DNA during chemotherapy in 11 stage IV EBVaGC patients whose baseline EBV-DNA was positive. EBV-DNA elevated when the disease progressed (N = 4) while it decreased when the patients got response (N = 7). Conclusions: This is the largest sample size study of EBVaGC in China. The incidence rate of EBVaGC was lower in China than TCGA study. There was no relationship between HP infection and EBV status. EBER detections between biopsy and surgical resection samples were highly consistent. Only one quarter of EBVaGC patients had positive plasma EBV-DNA. Plasma EBV DNA can be used for real-time monitoring of tumor progression in EBVaGC patients.