Epidemiology and treatment outcome of nasopharyngeal carcinoma in a low-incidence population - a DAHANCA analysis in Denmark 2000-2018.

Introduction: Nasopharyngeal carcinoma (NPC) is a rare disease and most studies have therefore been conducted in endemic areas. The aim of this study was to describe epidemiology and treatment outcomes of NPC in a population-based, non-endemic setting.

Material and methods: Patients with NPC diagnosed in Denmark from 2000 to 2018 were identified in the Danish Head and Neck Cancer Study Group (DAHANCA) database. Clinical records were reviewed to obtain missing data and confirm outcome, histological subtypes, Epstein-Barr virus (EBV)-status, prognostic factors, and treatment.

Results: NPC was identified in 394 patients corresponding to age-standardized incidence rates of 0.5 and 0.2 per 100,000 in men and women, respectively. The 5-year overall (OS) and disease-specific survival (DSS) were 56 and 66%. In multivariate analysis, stage, smoking, and histology affected both OS and DSS, as patients with undifferentiated carcinomas had superior outcomes. Tumor EBV-status was determined in 221 patients, of whom 160 (72%) tested positive. EBV-positivity was associated with an improved OS in univariate analysis, but not after adjustment for relevant clinical factors.

Interpretation: NPC is a rare malignancy in Denmark, and three in four patients have EBV-associated tumors. Tumor histology, smoking status, and stage, but not EBV-status, had independent prognostic impact on survival.