Treatment Initiation of Definitive Radiotherapy in Patients With Locally Advanced Head and Neck Cancer.

PurposeTo investigate the relationship between time to treatment initiation (TTI) of definitive radiotherapy and survival outcomes in locally advanced head and neck cancers (LAHNC).MethodsWe retrospectively included patients diagnosed between 2005 and 2015 from the Surveillance, Epidemiology, and End Results (SEER) database. The multivariate regression analysis, recursive partition analysis, penalized spline function, chi-square test, Kaplan-Meier method, and multivariate Cox proportional-hazards models were used for statistical analyses.ResultsA total of 18657 patients were included. Patients were stratified into 3 groups: no delay (<36 days), at risk of delay (36-61 days), and delay (>61 days). Compared to patients who initiated radiotherapy within 61 days, patients who initiated radiotherapy after 61 days had a higher risk of death in 5-year cancer-specific survival (CSS) (no delay vs. at risk of delay vs. delay: 58.7% vs. 60.5% vs. 50.5%) (P<0.001) and overall survival (OS) (no delay vs. at risk of delay vs. delay: 47.7% vs. 49.5% vs. 39.4%) (P<0.001). Patients in the delay group had worse outcomes in CSS (hazard ratio [HR], 1.209; 95% confidence interval [CI], 1.143-1.278; P<0.001) and OS (HR, 1.199; 95% CI, 1.146-1.256; P<0.001). In patients with oral cavity, oropharyngeal, and laryngeal cancers, the risk of death progressively rose as the treatment was delayed. However, there was no significant difference in the risk among patients with hypopharyngeal cancer.ConclusionsFor patients with LAHNC, delay of definitive radiotherapy leads to inferior survival. Our study highlights that the threshold of 36 and 61 days significantly affects survival and identifies patients experiencing these delays.