Differences in the association of time to treatment initiation and survival according to various head and neck cancer sites in a nationwide cohort

Objectives: To assess whether there are differences in the effects of time to treatment interval (TTI) on patient survival for head and neck cancer (HNC) sites in order to provide evidence that can support decision-making regarding prioritizing treatment. Materials and methods: Patients in the Netherlands with a first primary HNC without distant metastasis between 2010 and 2014 were included for analysis (N =10,486). TTI was defined as the time from pathologic diagnosis to the start of initial treatment. Overall survival (OS), cox regression analyses and cubic spline hazard models were calculated and visualized. Results: Overall, the hazard of dying was higher (HR = 1.003; 95 % CI 1.001-1.005) with each additional day until treatment initiation. The pattern, as visualized in cubic spline graphs, differed by site the hazard increased more steeply with increasing TTI for oral cavity cancer. For oropharyngeal and laryngeal cancer, a slight increase commenced after a longer TTI than for oral cavity cancer, while there was hardly an increase in hazard with increasing TTI for hypopharyngeal cancer. Conclusion: The relationship between longer TTI and decreased survival was confirmed, but slight variations in the pattern of the hazard of dying by TTI by tumour site were observed. These findings could support decisions on prioritizing treatment. However, other aspects such as extent of treatment and quality of life should be investigated further so this can also be included.