Epstein-Barr virus infection is not the sole cause of high prevalence for Hodgkin’s lymphoma in Saudi Arabia

Age adjusted incidence of Hodgkin’s Lymphoma (HL) is markedly higher in Saudi Arabia than in the United States. For example, HL accounts for 10.5% of all neoplasia in children 15 years and younger in Saudi Arabia. EBV virus infection, which can induce HL transformation has been suspected to cause high HL incidence in developing countries. To investigate the role of EBV for the high frequency of HL in Saudi Arabia, we analyzed 265 HL from Saudi Arabia and 58 HL from Europe for EBV infection by in situ hybridization with fluoresce in-conjugated Epstein-Barr virus (EBER) on tissue microarray (TMA) sections. All Saudi and European HL were analyzed in one staining run under identical conditions. Unexpectedly, our data show only minor, statistically insignificant differences in EBV infection rates between Saudi (64 out of 150 informative cases; 42.6%) and European HL (11 out of 30 informative cases; 33%; p=0.5). Within the Arabian population, EBV positivity was more frequent in 79 children (53%) than among 133 adults (36%; p=0.015). EBV positivity was also linked to high stage with EBV positivity in 36% of 69 stage I/II and 64% of 73 stage III/IV tumors (p=0.009). EBV infection was most frequently seen in mixed cellularity HL (63% of 27 cases). This was significantly more frequent than in nodular sclerosing HL (39% of 136; p=0.02). Interestingly, EBV positivity was associated with good prognosis in Saudi childhood HL (p=0.016) but with poor prognosis in Saudi adulthood HL (p=0.0048). In conclusion, our data strongly suggest that EBV is not the main cause for the high prevalence of HL in Middle East countries. Among others, this would be consistent with a major role of genetic susceptibility genes for HL in these populations. Saudi Arabia with high consanguinity and large families would be ideal to search for HL susceptibility genes