Nasopharyngeal carcinoma: nationwide trends in subtype-specific incidence and survival over 3 decades in a non-endemic area.

ABSTRACT

PURPOSE: To identify trends in incidence and survival of NPC, subdivided by EBV status and histopathological subtype, over a 30-year period in the Netherlands. METHODS: Anonymized data from the Netherlands Cancer Registry and the Dutch Nationwide Pathology Databank (PALGA) for the period 1989-2018 were linked to identify and classify NPC cases. RESULTS: Incidence of NPC remained stable, with an annual percentage change (APC) of - 0.2. (95% CI - 0.9; 0.5). EBV testing became routine only in the last decade, the incidence of EBV-positive tumors remained stable over this period (APC 1.2, 95% CI - 1.3; 3.8). An increase in EBV-negative tumors (APC 7.1, 95% CI 2.5; 11.9) and a decrease in untested tumors were found (APC - 10.7, 95% CI - 15.7; - 5.7). The incidence of non-keratinizing, differentiated tumors increased (APC 3.8, (95% CI 2.2; 5.5) while the incidence of other histological subtypes remained stable. Overall survival was better in patients diagnosed after 1998 (hazard ratio 0.8, 95% CI 0.6; 0.9). EBV status, histology, stage, and age were independently associated with relative excess risk of dying, but period of diagnosis was not. CONCLUSION: Testing for EBV increased over time, and a stable incidence of EBV-positive NPC over the last 10 years. The rising incidence of non-keratinizing, differentiated NPC mirrors data from the US and suggests a shift in non-endemic regions.