S634
Clinical – Head & neck
ESTRO 2026
1 Department of Oto-Rhino-Laryngology, Head and Neck Surgery, Aarhus University Hospital, Aarhus, Denmark. 2 Department of Experimental Clinical Oncology, Aarhus University Hospital, Aarhus, Denmark. 3 Department of Oto-Rhino-Laryngology, Head and Neck Surgery, Aalborg University Hospital, Aalborg, Denmark Purpose/Objective: Over the past thirty-five years, radiotherapy (RT) has remained the cornerstone of treatment for laryngeal cancer in Denmark. From conventional RT (66- 68Gy/33-34fx/5fx per week) stepwise refinements have been implemented through national clinical trials, introducing the hypoxic sensitizer nimorazole (N), accelerated RT (ART:66-68Gy/33-34fx/6fx per week), hyperfractionated RT (HART:76Gy/56fx/10fx per week), and concurrent cisplatin chemotherapy (C). Despite these advances, no comprehensive national overview exists for supraglottic squamous cell carcinoma (SGLSCC). The aim of the study is to describe the incidence, five-year disease-free survival (DFS), and overall survival (OS) of patients with SGLSCC in Denmark 1986-2020 in relation to treatment intensification in a national population-based cohort of consecutive patients. Material/Methods: All Danish patients diagnosed with SGLSCC in the period 1986-2020 were included. Patients were prospectively recorded in the Danish Head and Neck Cancer (DAHANCA) database, a nationwide registry with complete coverage. Adjusted standardized survival estimates were derived from flexible parametric survival models. Initial models assessed calendar period as exposure, adjusting for age, sex, T- and N-classification. The final model used treatment as exposure, with calendar year modelled as piecewise linear splines to capture secular trends, following a predefined causal framework (DAG) to address confounding. Results: A total of 3,154 patients were identified. Age- standardized incidence decreased from 2.62 to 1.18 per 100,000, with a more pronounced decline in males (4.09 to 1.63) than in females (1.36 to 0.74). Survival improved significantly over time among the 3,070 patients treated with RT. Adjusted 5-year DFS increased from 31.7% in 1986–1990 to 42.0% in 2016– 2020 in the total cohort, with a similar OS increase from 33.9% to 45.2%. Compared with RT alone, all subsequent treatment strategies were associated with improved outcomes. Transition from RT to ART improved adjusted 5-year DFS by 10.1% (HR=1.38) and OS by 7.6% (HR=1.26). Adding nimorazole (ART+N) increased adjusted 5-year DFS by 10.8% (HR=1.39) and OS by 11.9% (HR=1.44) compared to ART alone. Concurrent cisplatin (ART+C±N) further improved
adjusted 5-year DFS by 7.3% (HR=1.26) and OS by 7.3% (HR=1.27) compared with ART+N. Dose escalation from ART (ART+C±N) to HART (HART+C+N) further improved adjusted 5-year DFS by 20.8% (HR=2.30) and OS by 26.3% (HR=3.30).
Conclusion: The incidence of SGLSCC in Denmark declined markedly from 1986–2020, accompanied by significant gains in survival. These improvements reflect the stepwise implementation of evidence-based treatment guidelines developed through DAHANCA, including nimorazole, accelerated and hyperfractionated RT, and concurrent chemotherapy. Keywords: Laryngeal cancer, survival, radiotherapy
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