The burden and outcome of nasopharyngeal carcinoma in Sweden.

Abstract

Introduction: The purpose of this study is to present the nationwide disease burden and survival of nasopharyngeal carcinoma (NPC) in Sweden. The subcohort from the Stockholm-Gotland region was included to investigate the prevalence of Epstein-Barr virus (EBV) in NPC and to describe pattern of relapse.

Methods: This population-based nationwide study included patients diagnosed with NPC in Sweden during 2008-2021. The series was retrieved from the Swedish Head and Neck Cancer Register. Age at diagnosis, sex, tumor histopathology, stage, treatment intent, treatment, radiation dose, follow-up time, time to relapse, and site of relapse were recorded. The Stockholm-Gotland region series was used to obtain an updated histopathological analysis including EBV status and to analyze site of relapse.

Results: The nationwide study cohort comprised 399 patients, 33% were female. Mean age at diagnosis did not differ between the sexes: 56.3 years for females, 57.5 years for males. Seventy-one percent presented with Stage III or IV. The 5-year overall survival (OS) was 73.2%. In the regional cohort, 73.9% were EBV positive. In the competing risk analysis, the cumulative incidence of distant metastatic relapse was higher than that of local and/or regional relapse at 5 years (18.7% vs. 12.4%). However, the confidence intervals were wide, and the difference should be interpreted with caution.

Interpretation: The survival outcome in our study seems comparable to previous studies in nonendemic countries. There was a high percentage of EBV-positive tumors compared with the previous studies in nonendemic countries.