Molecular diagnosis of nasopharyngeal carcinoma using detection of Epstein-Barr virus latent membrane protein-1 gene in cervical metastatic lymph nodes

Abstract

Background Cervical lymphadenopathy could be a manifestation of occult nasopharyngeal carcinoma (NPC). Epstein-Barr virus (EBV) is frequently detected in NPC, and its malignant transformation is associated through the action of the oncoprotein latent membrane protein-1 (LMP-1). Purpose The aim of this study was to investigate whether a primary nasopharyngeal origin could be localized by detection of EBV LMP-1 gene in cervical metastatic lymph nodes. Materials and methods In this prospective study, 32 paraffin-embedded tissues of various head and neck carcinomas and 20 normal tonsil specimens were examined for the presence of LMP-1 gene, using polymerase chain reaction. Results Ten of 12 nasopharyngeal biopsies and 8 of 10 metastatic lymph nodes of the same NPC were positive for LMP-1 gene. The LMP-1 gene was detected in metastatic lymph nodes of NPC, with a sensitivity of 80%, specificity of 100%, positive predictive value of 100%, and negative predictive value of 91%. On the contrary, the LMP-1 gene was not detected in any of the samples of other head and neck carcinomas and their metastatic nodes as well as in tonsillar specimens. There was a significant association between the presence of LMP-1 gene and tumor location in the nasopharynx ( P < .0001). Conclusion The presence of LMP-1 gene in metastatic cervical lymph nodes is significantly associated with nasopharyngeal origin of the carcinoma. Meanwhile, EBV has no role in the tumorigenesis of carcinomas arising from other head and neck regions.