Human papillomavirus and Epstein-Barr virus in nasopharyngeal carcinoma in a non-endemic Eastern European population

Nasopharyngeal carcinoma (NPC) is a rare malignancy in the Czech Republic and Slovakia, with the standardized incidence rate of < 1:100000 person-years. Viral status of NPC in these non-endemic Eastern European regions is currently unknown. In a retrospective study, we evaluated the presence of EBV and HPV in 62 NPC cases. EBV status was determined by the use of in situ hybridization (ISH) for EBV encoded small RNA 1 (EBER1). HPV status was examined with p16 immunohistochemistry, DNA ISH and DNA polymerase chain reaction. Sixty-one studied cases showed non-keratinizing morphology and one was keratinizing squamous cell carcinoma. Only one NPC with non-keratinizing morphology was scored as p16-positive (nuclear and cytoplasmic staining >= 70% of tumor cells). This case was positive for high-risk HPV by ISH and the DNA PCR confirmed the presence of HPV18 type. At the same time, this case was found negative for EBV. Remaining sixty-one cases that were scored as p16-negative were all found HPV-negative by ISH and the DNA PCR. EBV was detected in 85.5% (53/62) of cases and 9 cases were EBV-negative, including the case of keratinizing NPC. In contrast with previous reports on the prevalence of EBV-positivity in Caucasian patients with NPC, the majority of patients coming from this non-endemic region show EBV-positivity; therefore, they may be candidates for novel EBV-targeting therapies. Conversely, HPV-positive NPC is very rare and HPV does not seem to play a significant role in the etiopathogenesis of NPC in these Eastern European populations.