BACKGROUND: Oropharyngeal carcinomas (OPCs) constitute a significant and increasing proportion of head and neck carcinomas and are an important global cause of morbidity and mortality. The purpose of this study was to determine trends in incidence and survival in OPC in the Danish population from 1980 to 2014.

METHODS: This study included all patients registered in the nationwide Danish Cancer Registry over the period 1980-2014. The age-adjusted incidence rates (AAIR) per 100,000, annual percentage change (APC) and average annual percent change (AAPC) were evaluated. Five-year relative survival (RS) was calculated with Cox regression analyses in relation to gender, anatomical location and histology.

RESULTS: A total of 6555 patients (69% male) were included, with a median age at diagnosis of 60 years. The AAIR of patients with OPC increased from 0.815 per 100,000 in 1980 to 4.51 per 100,000 in 2014 with an AAPC of 5.3. The 5-year RS increased significantly from 33.1% over the period 1980-1984 to 58.5% (25.4% points) over the period 2010-2014. With no significant difference stratified for gender. Tumors located at the palatine tonsils (n = 3333) and salivary gland OPC (n = 90) had significantly better survival compared with other sub-locations and histology subtypes. In the APC model the birth cohort effect rate ratio increased until 1925 and then decreased until 1935 from which point it increased in the last cohorts.

CONCLUSIONS: In this population-based study, we observed a significant increase in the incidence of OPCs and in the RS for OPC. We also identified a profound birth cohort effect on the incidence.