The burden and outcome of nasopharyngeal carcinoma in Sweden

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.

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.

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.

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.