Polymyositis/dermatomyositis and nasopharyngeal carcinoma: The Epstein–Barr virus connection?

BackgroundPolymyositis (PM) and dermatomyositis (DM) are associated with high risk of nasopharyngeal carcinoma (NPC) in Asian countries. Epstein–Barr virus (EBV) might induce autoimmunity and malignancies in susceptible individuals.ObjectivesTo investigate the association of EBV with PM/DM and NPC in PM/DM patients.Study designSerum levels of anti-EBV viral capsid antigens (VCA) and anti-EBV-coded nuclear antigens-1 (EBNA-1) antibodies were measured by ELISA, and EBV DNA loads were determined using real-time PCR for 98 PM/DM patients, 94 systemic lupus erythematosus (SLE) patients and 370 healthy controls (HC). Anti-transfer-RNA synthetase antibodies (ASA) were determined by radioimmunoprecipitation for PM/DM patients.ResultsThirteen (13.3%) of PM/DM patients vs. none of SLE patients had detectable NPC. ASA were detectable in 31.7% of PM/DM without malignancy, while lack of ASA in any PM/DM patient with NPC. IgA anti-EBNA-1 were detectable in 30.6% of PM/DM patients and 31.9% of SLE patients, but only in 4.1% of HC (odds ratio [OR] 10.44 and 11.12 respectively, both p < 0.001). Significantly higher positivity for IgA anti-EBNA-1 were observed in PM/DM with NPC than in those without malignancy (OR 44.7, p < 0.01). Significantly higher positivity for EBV genome were observed in PM/DM with NPC than in those without malignancy (OR 43.9, p < 0.01), in SLE patients (OR 13.2, p < 0.05) and in HC (OR 99.4, p < 0.001). EBV DNA loads were significantly higher in PM/DM with NPC compared with those without malignancy and HC.ConclusionsOur results showed a positive association of EBV with PM/DM and NPC. PM/DM patients who have IgA anti-EBNA-1 or increased EBV DNA loads should be highly suspected to have occult NPC.