Long-term toxicity following radiation therapy for head and neck squamous cell carcinoma: A retrospective study analyzing the effect of concurrent chemotherapy and advanced t-stage on late treatment-induced toxicities.

e17560 Background: There are approximately 436,000 survivors of head and neck squamous cell carcinoma (HNSCC) in the U.S. Toxicities related to definitive chemoradiation or radiation therapy can persist for many years, with some toxicities not presenting clinically until five or more years after definitive treatment. Long-term management of late radiotherapy effects is thus warranted. Methods: This retrospective chart review has three aims: (1) comprehensively assess overall late effects of definitive radiation and chemoradiation; (2) compare treatment-related toxicities between definitive radiation and chemoradiation; and (3) compare treatment-related toxicities between patients with TNM stage T1/T2 tumors to T3/T4 tumors. Late term effects were assessed using 17 toxicity categories including xerostomia, dysphagia, and neck fibrosis. HNSCC patients included in the study were those seen by a single practitioner for follow-up of definitive radiation or chemoradiation, without a history of surgical intervention to the primary site, between June 2017 and June 2018 (N = 49). Results: The median time from the end of treatment to the most recent follow-up was 8.53 years (1.17-24.08 years). In the total cohort, the most common late effect was xerostomia (78%, N = 38), followed by dysphagia (43%, N = 21), and neck fibrosis (27%, N = 13). For the majority of toxicity categories (11 of 17), the cohort that received definitive chemoradiation had higher rates of toxicity than the cohort that received definitive radiation alone. Additionally, for the majority of toxicity categories (10 of 17), the cohort of T3/T4 tumors had higher rates of long-term toxicity than the cohort of T1/T2 tumors. Conclusions: Although the patient population in this study has excellent locoregional control after definitive radiation or chemoradiation, the majority of patients suffer from long-term treatment-related toxicities. Long-term follow up care is needed to manage the late effects of radiotherapy that can develop and persist for years after treatment completion.