Clinical and oncological outcome in locoregional advanced oral squamous cell carcinoma treated by primary chemoradiation

• 41.5% of the patients developed local recurrence and 6.7% cervical lymph node metastasis. • The rate of distant metastasis was 23.7%, mostly associated with accompanying locoregional recurrence. • The rate of osteoradionecrosis was 5.9% with 50% of the patients receiving free flap reconstruction for extended disease. • The 3-year overall survival was 31,4% with advanced tumor stage and reduced clinical performance score at the start of treatment being independently associated. Despite advancements in current cancer treatments, surgical resection remains to date the gold standard in the treatment of oral squamous cell carcinoma (OSCC). Primary chemoradiation (CRT), can be considered as an alternative treatment in cases of locoregional advanced diseases or patients declining surgery. The aim was to assess the clinical and oncological outcome of patients with OSCC receiving CRT. In this retrospective cohort study, all patients receiving primary CRT between 01/2013–12/2023 were assessed. Endpoints of this study were the overall survival (OS), the rate of osteoradionecrosis of the jaw (ORNJ) and the recurrence-free survival (RFS). Overall, 125 patients were included. During follow-up, 42.4 % of patients developed local recurrence and 11.3 % cervical lymph node metastasis. The overall rate of distant metastasis was 24.8 %, which was significantly higher in patients with locoregional recurrence (39.6 % vs. 13.9 %, p < 0,01). The rate of ORNJ was 5.9 %. The 3-year OS and RFS were 30.2 % and 34.0 %, respectively. UICC-stage IVB and ECOG-score 2 were independently associated with worse OS. There was a trend towards the association of salvage surgery in case of locoregional recurrence with a 69 % reduction in the risk of death. In this study, primary CRT for OSCC was associated with poor outcome. These findings highlight on one hand the relevance of surgery in cases of resectable tumors and on the other hand the need for further improvements towards the patient population with irresectable tumors, where primary CRT is currently the only guideline-supported treatment option.