Definitive radiation with concurrent cetuximab vs. radiation with or without concurrent cytotoxic chemotherapy in older patients with squamous cell carcinoma of the head and neck: Analysis of the SEER-medicare linked database

Objective: To evaluate OS and toxicity after definitive radiation with concurrent cetuximab (CTX-RT) compared to radiation with concurrent cytotoxic chemotherapy (CRT) in older HNSCC patients via the SEER-Medicare linked database. Materials and Methods: We used the SEER-Medicare linked database to evaluate OS in HNSCC patients (Oropharynx, Larynx, Hypopharynx, Nasopharynx) diagnosed over 2005-2011, following FDA approval of cetuximab in combination with radiation therapy (RT) in March 2006. Results: 2135 beneficiaries were identified. Median age was 73 (66-104) years. Primary was oropharynx (61%), hypopharynx (15%), nasopharynx (5%), and larynx (19%). CRT was platinum based in 82% of patients. CTX-RT was associated with worse OS compared to CRT (P < 0.005), and similar OS to RT (P = 0.21); 5-year OS was 46% for CRT, 35% for CTX-RT, 32% for RT. Patients were more likely to receive CTX-RT vs. CRT if they had oropharyngeal vs nasopharyngeal primary, Charlson comorbidity index 2 vs 0, older age at diagnosis. Multivariable Cox regression showed that CTX-RT was associated with a higher risk of death compared to CRT (hazard ratio = 1.23, 1.07-1.42; p = 0.005), after stratifying by stage and primary site, and adjusting for gender, race, age, income, Charlson comorbidity index, marital status, hospital type, and year of diagnosis. There were no differences in dysphagia, gastrostomy tube placement, pneumonia, and weight loss over the first 12 months after diagnosis. Conclusion: Despite the limitations to comparative effectiveness evaluation in population-based registries, our data suggest that cytotoxic chemotherapy should be used with RT for eligible older HNSCC patients.