Trends in all-cause five-year mortality after head and neck cancers diagnosed over a period of 33 years. Focus on estimated degree of association with human papillomavirus.

BACKGROUND: Factors influencing survival after head and neck cancer (HNC) include among others stage, age, and sex. More recently, human papillomavirus (HPV) positivity has been described as a favorable prognostic factor in relation to some HNCs.
MATERIAL AND METHODS: In this nationwide register-based cohort study of all 20 925 individuals diagnosed with squamous cell carcinoma of the head and neck (HNSCC) in Denmark 1978-2010, we investigate secular trends in all-cause five-year mortality after HNSCC according to the anticipated degree of association with HPV using a Cox proportional hazards model. Furthermore, we examine whether any trend over time differed according to sex, stage, and age at diagnosis.
RESULTS: All-cause five-year mortality after HNSCC has decreased over time. The greatest decrease was seen in the last decade (2000-2010) among patients with HNSCC at sites estimated to be strongly associated with HPV, i.e. the base of the tongue and the tonsils, where a 28% decrease per five years (e.g. HRbase of tongue/tonsils=0.72; 95% CI 0.64-0.81) was observed. When examining sex- and age-specific time trends, the decrease in mortality was most pronounced among male patients and patients below 60 years at diagnosis. In contrast, no clear pattern was observed when examining five-year all-cause mortality trends according to stage.
CONCLUSION: All-cause five-year mortality after HNSCC has decreased significantly in Denmark from 1978 to 2010, especially for HNSCCs at sites anticipated to be strongly associated with HPV, possibly due to an increasing proportion of HPV-positive HNSCCs.