Definitive (Chemo)Radiation Therapy is a Curative Alternative for Standard of Care in Advanced Stage Squamous Cell Carcinoma of the Oral Cavity

Abstract

Surgery with or without adjuvant radiotherapy is standard of care (SOC) in patients with locally-advanced oral cavity carcinoma (OCC). However, when SOC is not feasible, definitive radiotherapy might be an alternative. Although in general this treatment is assumed to be inferior to SOC with regard to disease control, data on outcome of this approach is scarce. In this study, we test our hypothesis that definitive (chemo)radiotherapy is a curative alternative for standard of care in locally-advanced squamous cell carcinoma of the oral cavity when surgery is not feasible. We retrospectively analyzed all patients with locally-advanced OCC, treated between 2000-2013 with definitive radiotherapy or chemoradiotherapy (RT group) by historical patient chart in a single institution. Clinical outcome of these patients was analyzed in view of comparable patients treated in our hospital with standard of care (surgery with adjuvant radiotherapy, SOC group). Groups were matched on age, tumor stage, tumor subsite and comorbidity. A comparison of local tumor volume was outside the scope of this study. The minimal follow up was 2 years. Primary endpoints were locoregional control (LRC), disease-free survival (DFS), disease specific survival (DSS) and overall survival (OS) at 5 years, calculated by Kaplan-Meier method. Both groups consisted of 93 patients; all baseline characteristics were equally distributed (p=0.06-0.98). Fifty-nine patients had cT4a tumors in the RT group compared to 47 patients in the SOC group (p=0.10). For cT4a tumors, local control at 5 years was 45% for the RT group, compared to 82% for the SOC group (p<0.001). In the RT group, 83 patients (89%) received definitive radiotherapy for functionally inoperable tumors. For this subgroup of patients, the 5-year local control was 53% for the RT group, compared to 89% for the matched patients receiving SOC (p<0.001). In the RT group, the overall LRC at 5 years was 44%, DFS was 20%, DSS was 36% and OS was 24%. In the SOC group, the overall LRC at 5 years was 80%, DFS was 47%, DSS was 70% and OS was 47% (p=0.002 for OS, p<0.001 for all other endpoints). Within 1 to 86 days, 6 patients (6%) died from treatment-related toxicity in the RT group and 1 patient after SOC (p=0.12). Standard of care (surgery with adjuvant radiotherapy, SOC) for locally-advanced OCC results in better disease control and survival compared to definitive (chemo)radiotherapy. However definitive (chemo)radiotherapy is a curative alternative in patients often considered beyond cure and may be offered when SOC is not feasible and to those patients who have a wish for organ- and function-preservation. In this study, one might find larger tumor bulk in the RT group, as these patients mostly received radiotherapy for functionally inoperable disease. Therefore, we suggest to measure tumor volume for a more strict comparison of both groups in future research.