Treatment and outcomes of nasopharyngeal carcinoma in a unique non-endemic population.

Abstract

Nasopharyngeal carcinoma (NPC) is common in Southeast Asia. Due to the influx of immigrants from this region, the incidence in British Columbia is increasing. Current literature from non-endemic populations encompasses heterogeneous cohorts. This study examines NPC in a North American population, with a high incidence, to understand the population's characteristics, treatment outcomes and recurrence patterns. A retrospective analysis of patients treated for primary and recurrent NPC over 15-years. Regression analyses were used to identify predictors of disease recurrence and death. A subgroup analysis of the locoregional recurrence cohort was conducted. Five-year survival outcomes were determined. 601 patients were included. Asian ethnicity comprised 77% and the majority had non-keratinizing carcinoma (81%). In total, 19.3% of patients experienced recurrence: 58% local, 22% regional and 20% distant. Five-year overall survival was 70%. Smoking, advancing T-stage, poorer performance status and advanced overall stage were all associated with worse overall survival (p<0.05). Asian ethnicity improved overall survival but not recurrence free survival. Similar features in addition to non-keratinizing histology were associated with increased locoregional recurrence (p<0.05). Competing risk analysis indicated radiotherapy alone had a higher recurrence relative to chemoradiotherapy (HR 1.91, CI 1.17-3.09, p=0.01). We report the largest study evaluating treatment and outcomes of NPC in a non-endemic population. This unique population falls between described endemic and non-endemic populations. Non-keratinizing pathology and primary radiotherapy did not affect survival; however, both had a propensity for recurrence. Finally, patients experienced more locoregional and less distant recurrence, supporting that this cohort may be amenable to curative salvage therapy.