Clinical Value of the Epstein-Barr Virus and p16 Status in Patients with Nasopharyngeal Carcinoma: A Single-Centre Study in Japan

Background: The clinical significance of the Epstein-Barr virus (EBV) status and p16 expression was unknown in nasopharyngeal carcinoma (NPC). Methods: We retrospectively studied our pathology database for 13 years to determine the prevalence of EBV and p16 expression and their association with prognosis in cases of NPC. We performed immunohistochemistry for the p16 protein and in situ hybridization (ISH) for EBV-encoded small RNAs and human papillomavirus (HPV) DNA. Results: Of the 43 patients with NPC, 27 (63%), 6 (14%), and 10 (23%) cases were EBV positive, EBV negative with keratinization, and EBV negative without keratinization, respectively. No cases were HPV positive by ISH. Among the 21 EBV-positive tumours that were tested for p16, only 2 tumours were p16 positive. The keratinization-positive group included only males, typically >60 years of age (5 of 6) and with T4 tumours (3 of 6). In contrast, the EBV-positive cohort tended to be younger (<60 years, 13 of 27) and have progressive N-stage tumours (N2-3, 14 of 27). The keratinization and EBV-negative cohort included predominantly males (9 of 10) who were likely p16 negative (4 of 10) and smokers (7 of 10). Multivariate analysis confirmed that keratinization was an independent prognostic factor for progression-free survival. Conclusion: In areas, such as Japan, that are nonendemic for both EBV and HPV, the causality of NPC appears to be more heterogeneous.