(A549) Factors Affecting Adjuvant Radiation Therapy Compliance in Advanced-Stage Head and Neck Squamous Cell Carcinoma Patients

Introduction: The optimal treatment for advanced-stage head and neck squamous cell carcinoma (HNSCC) is multi-modal, and incomplete adjuvant radiation therapy (adj RT) is associated with inferior survival. This study aims to investigate how distance from treatment facilities affects compliance with treatment and survival.

Methods: This retrospective cohort study included adult HNSCC patients who received primary surgical resection at a single academic tertiary care center and were recommended to undergo adj RT or chemo-RT from 2010-2023. Exclusion criteria included neoadjuvant treatment, surgical resection alone, and nasopharyngeal subsites. Patients were divided into cohorts based on completion of adj RT, with incomplete adj RT defined as receiving < 100% of the prescribed dose.

Results: To date, 121 patients were included with 18 (14.8%) in the incomplete adj RT cohort. The incomplete RT cohort traveled 11.6 miles farther than the complete RT cohort (p=0.487). The incomplete RT cohort had worse 1-year (61.1% vs 88.0%, p=0.010) and 5-year (0.00% vs 55.3%, p< 0.0001) overall survival (OS), and more patients alive at 1 year traveled < 20 miles for adj RT (93.6% vs 73.2%, p=0.005). Completed adj RT was protective of death at 1 year (OR 0.203, 95% CI 0.0430-0.963, p=0.0447), whereas travelling ≥20 miles to adj RT increased odds of death at 1 year (OR of 5.27, 95% CI 1.35-20.6, p=0.0169) after accounting for demographics, primary site, staging, margin status, chemotherapy, package time, and comorbidities. Older age (OR 1.068, 95% CI 0.986-1.16, p=0.109) and travelling ≥20 miles for adj RT (OR 3.488, 95% CI 0.643-18.9, p=0.148) trended toward significance as factors affecting completion of adj RT.

Conclusions: Preliminary data suggests that incomplete adj RT is associated with worse OS than a complete course. Traveling ≥20 miles to adj RT trended toward significantly affecting the odds of completing adj RT and is associated with increased odds of death at 1 year. The results could be used to identify at-risk populations and improve support to help patients maximize the survival benefits of treatment. Data collection is ongoing.