(0254) Survival Associations of Timely Postoperative Radiotherapy Among Head and Neck Cancer High-Risk Subgroups

Introduction: Effective implementation of timely postoperative radiation therapy (PORT) as a quality metric for head and neck squamous cell carcinoma (HNSCC) care may be a promising intervention aimed at reducing survival disparities in subgroups with the highest risk of mortality – advanced stage and black race. We sought to determine if the association between timely PORT for surgically treated HNSCC and survival varies among clinical and demographic high-risk subgroups.

Methods: Patients with HPV-negative HNSCC treated with surgery and PORT were identified for this retrospective cohort study using the National Cancer Database, 2004 - 2016. Exposure was PORT delay greater than 6 weeks, modified by race and stage. Overall survival differences were assessed by Kaplan-Meier survival curves and Cox proportional hazards models, stratified by race, overall stage, and PORT delay. Sensitivity analyses were performed with varying time-to-PORT intervals (4 through 9 weeks after surgery).

Results: The association between better overall survival and starting PORT within 6 weeks after surgery was observed in patients with stage I or IV disease only. When stratified by race, timely PORT was associated with inferior overall survival in black patients with stage IV disease, after adjusting for covariates. There are no PORT timing cut-offs where black patients with stage IV disease benefit from earlier initiation of PORT, however, the negative effect between their PORT timing and overall survival ceases at higher time-to-PORT cutoff values (≥7 weeks).

Conclusions: In our study cohort, guideline-adherent PORT timing was associated with the largest survival benefit for stage IV disease. Unexpectedly, this effect reversed for black patients with stage IV disease in which timely PORT was associated with inferior overall survival. Based on these data, guideline-adherent initiation of PORT is unlikely to reduce the survival disparities in black patients, including those with advanced stage disease, suggesting other interventions are needed to address this disparity.