Epstein‐Barr virus‐associated gastric carcinoma in southern India: A comparison with a large‐scale Japanese series

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Abstract
Epidemiological and clinicopathological features of Epstein‐Barr virus (EBV) associated gastric carcinoma was compared in India and Japan, two countries differing markedly in gastric cancer incidence. Using in situ hybridization assay, the presence of EBV‐encoded small RNA (EBER) was examined in 215, and 2,011 gastric cancer cases in Kerala, India, and Japan, respectively. Ten cases (5%), all males, in the Indian series were EBER‐positive. This frequency was similar to that in the Japanese series (6.2%). As was the case with Japanese series, the EBV‐associated gastric carcinoma in the Indian series was observed most frequently in the middle part of the stomach (1 in antrum, 4 in middle part, 2 in cardia, and 3 unknown), and, histologically, the diffuse type Lauren's classification (8 cases) was more common than the intestinal type (2 cases). Virus subtyping by PCR‐RFLP revealed that all of the 10 EBV strains isolated from the EBER‐positive Indian cases were subtype A, and wild‐type F for Bam HI F region. In Bam HI I region, 8 cases were type C and the remaining 2 cases were type D. In either series, there was no significant difference in the frequency of tumors with p53 overexpression between EBER‐positive and ‐negative cases. However, the proportion of cells with p53 overexpression in EBER‐negative tumors was significantly higher than that in EBER‐positive tumors regardless of histological type in both series. In conclusion, the frequency and major clinicopathological features of EBV‐associated gastric carcinoma in south India were similar to those observed in Japanese series although gastric cancer incidence in these two countries differs markedly. J. Med. Virol. 68:384–389, 2002.