Survival impact of treatment-related time intervals in nasopharyngeal carcinoma in the United States.

Objective: To determine if delayed or prolonged treatment-related time intervals (TRTIs) was associated with survival in patients with nasopharyngeal carcinoma (NPC) undergoing curative-intent concurrent chemoradiation (CCRT). The TRTIs investigated were duration of radiation treatment (RTd), time to radiation start (TTR), and time to chemotherapy start (TTC).

Methods: Observational cohort study using the National Cancer Database (NCDB). In this observational cohort study, 3,893 eligible patients with NPC were identified from the NCDB. Patients received CCRT of at least 66 grays and radiation treatment time of at least 40 days. Separate univariable Cox regression model was used to analyze overall survival (OS) as a function of TRTIs, as well as for Charlson/Deyo Score, tumor classification, node classification, histological type, ethnicity, age, sex, and facility type. Upon finding significance at P < 0.05, the multivariable Cox regression analysis with backward elimination was performed to yield the final prediction model. Results were considered statistically significant when P < 0.05.

Results: Radiation treatment was significantly associated with OS in the univariable analysis (hazard ratio: 1.006, 95% confidence interval = 1.004-1.008, P < 0.001). However, RTd was not related to OS in the multivariable analysis (P = 0.19). The TTR and TTC variables were not associated with OS in the univariable analysis (P = 0.88 and P = 0.88, respectively).

Conclusion: TRTIs were not independently associated with OS in this cohort of NPC patients in the NCDB. Future research into the association of TRTI with other disease outcomes, such as disease-free survival and locoregional control, is needed.

Level Of Evidence: NA. Laryngoscope, 129:2514-2520, 2019.