Radiotherapy with or without concurrent cetuximab in HPV-positive oropharyngeal squamous cell carcinoma – A pooled analysis from two ARTSCAN trials

AbstractBackground The radiosensitizing effect of epidermal growth factor inhibitors (EGFRIs), such as cetuximab, in patients with p16-positive HPV-associated oropharyngeal squamous cell carcinoma (HPV + OPSCC) is not clear. There is no randomized trial investigating the addition of EGFRI to radiotherapy (RT) alone specifically in HPV + OPSCC, and available evidence in subgroup analyses have mostly suggested discouraging results. The current analysis provides additional data by combining results from two randomized trials. Materials and Methods Patients from two randomized ARTSCAN trials were included. The RT alone-group consisted of patients treated with conventionally fractionated RT (68.0 Gy in 34 fractions over 6.5 weeks) in the first ARTSCAN trial. The cetuximab group comprised patients treated with conventionally fractionated RT (same RT-schedule) and receiving concurrent cetuximab in the ARTSCAN III trial. Only patients with HPV + OPSCC were included. Comparisons between groups were made by univariable and adjusted Cox regression models, and illustrated with the Kaplan-Meier method. Results 74 and 89 patients were eligible in the first ARTSCAN trial (RT alone) and ARTSCAN III (RT + cetuximab), respectively, with a median follow-up of 5.3 (interquartile range 5.0–5.5) years. Baseline characteristics were generally well-balanced. The five-year loco-regional control for RT alone was 84% (95%CI 76–93) and for RT + cetuximab 82% (95%CI 75–91), with an adjusted hazard ratio of 1.18 (95%CI 0.54–2.6, p = 0.70). Interpretation The study does not support a radiosensitizing role when adding EGFRI cetuximab to RT in patients with HPV + OPSCC.