Epstein-Barr virus in nasopharyngeal carcinoma in Indian patients

Formalin fixed paraffin embedded tissue blocks from 40 cases of nasopharyngeal carcinoma were investigated for the presence of Epstein-Barr virus (EBV). Heminested polymerase chain reaction was employed to amplify U 2 region of EBV DNA coding for EBNA 2 gene. This is the first study of its kind carried out in India. EBV was detected in 28 out of 40 (70%) nasopharyngeal carcinomas. Type A EBV was identified in 20 cases (71.4%), type B in 7 cases (25%) and coinfection in one case (3.5%). Either type A, or type B EBV, was identified in 22 out of 23 cases (95.7%) of undifferentiated nasopharyngeal carcinoma and 6 out of 15 cases (40%) of non keratinized squamous carcinoma. The higher incidence of EBV in non keratinized squamous carcinoma of nasopharynx assumes importance in view of the contrary reports in other studies. 26 cases were from Western India, of which 15 (57.6%) showed presence of type A EBV and 2 (7.6%) type B EBV. From Eastern Indian particularly Assam, 4 our of 5 cases showed positivity for type B EBV and 1 a coinfection. Whereas, from Bihar 3 out of 4 cases showed presence of type A EBV. From Middle East (Arabs) type A EBV was detected in 3 out of 5 cases of nasopharyngeal carcinomas. Geographically, type A EBV was far more prevalent in Western India, while in Eastern India particularly Assam, all five vases were positive for type B EBV. Thus, a significant variation in the type of EBV infection was observed in nasopharyngeal carcinoma in different ethnic populations in India.