Increased Prevalence of EBV Infection in Nasopharyngeal Carcinoma Patients: A Six-Year Cross-Sectional Study

Abstract

Epstein Barr Virus (EBV) is implicated in the carcinogenesis of nasopharyngeal carcinoma (NPC) and currently associated with at least 1% of global cancers. The differential prognosis analysis of NPC in EBV genotypes remains to be elucidated. Medical, radiological, pathological, and laboratory reports of 146 NPC patients were collected retrospectively over a 6-year period between 2015 and 2020. From the pathology archives, DNA was extracted from tumor blocks and used for EBV nuclear antigen 3C (EBNA-3C) genotyping by nested polymerase chain reaction (PCR). We found a high prevalence of 96% of EBV infection in NPC patients with a predominance of genotype I detected in 73% of NPC samples. Histopathological examination showed that most of the NPC patients were in the advanced stages of cancer: stage III (38.4%) or stage IV-B (37.7%). Only keratinized squamous cell carcinoma was significantly higher in EBV negative NPC patients compared with those who were EBV positive (OR = 0.01, 95%CI = (0.004-0.32; p = 0.009)), whereas the majority of patients (91.8%) had undifferentiated, non-keratinizing squamous cell carcinoma, followed by differentiated, non-keratinizing squamous cell carcinoma (7.5%). Although NPC had metastasized to 16% of other body sites, it was not associated with EBV infection, except for lung metastasis. A statistically significant reverse association was observed between EBV infection and lung metastasis (OR = 0.07, 95%CI = (0.01-0.51; p = 0.008)). Although 13% of NPC patients died, the overall survival (OS) mean time was 5.59 years. Given the high prevalence of EBV-associated NPC in our population, Saudi could be considered as an area with a high incidence of EBV-associated NPC with a predominance of EBV genotype I. A future multi-center study with a larger sample size is needed to assess the true burden of EBV-associated NPC in Saudi Arabia.

Keywords: EBV; NPC; Saudi Arabia; epidemiology; genotyping; prevalence.

Figure 1

Histopathological examination of nasopharyngeal carcinoma observed under 20× magnification. (A) Keratinizing squamous cell carcinoma. (B) Non-keratinizing differentiated squamous cell carcinoma. (C) Non-keratinizing undifferentiated squamous cell carcinoma. (D) EBER in situ hybridization stain for EBV positive. (E) EBER in situ hybridization stain for EBV negative.

Figure 2

(A) Disease-free survival; (B) overall survival curves of all patients by EBV status.

Figure 3

(A) First round PCR product of EBNA-3C gene. Lane 1 is a 500 bp DNA Ladder (50–500 bp). Lanes 2, 3, and 5–8 represent EBV type I amplicons “EBNA-3C, 153 bp”. Lane 4 represents EBV type II amplicons “EBNA-3C, 246 bp”. Lane 9 corresponds to the negative control (nuclease-free water with master mix). Lanes 10 and 11 correspond to the EBV-negative control samples. (B) Second round of the PCR product of the EBNA-3C gene. Lane 1 is a 500 bp DNA Ladder (50–500 bp). Lanes 2, 3, and 5–8 represent EBV type I amplicons “EBNA-3C, 75 bp”. Lane 4 represents EBV type II amplicons “EBNA-3C, 168 bp”. Lane 9 corresponds to the negative control (nuclease-free water with master mix).