ESTRO 2025 - Abstract Book

S1051

Clinical – Head & neck

ESTRO 2025

(excluding p16+) treated with definitive radiotherapy (RT) or radiochemotherapy (RCHT) at three centers in the Czech Republic from 2015–2020.

Material/Methods: The cohort included 224 patients from three major centers - center one (C1, n = 71), two (C2, n = 74), and three (C3, n = 79). Inclusion criteria: HPV-negative squamous cell head and neck cancer, disease stage III or IVA/B. Exclusion criteria: incomplete RT - total radiation dose less than 70,0 Gy in 2 Gy fractions or equivalent. Overall survival (OS) and local control (LC) were calculated from the RT completion to death and local recurrence/progression, respectively, using Kaplan-Meier and cumulative incidence methods. Demographic, clinical, and treatment-related factors and inter-center differences were analyzed. Results: The cohort included 183 men (82%), a median age of 60 years, and 137 (61%) women treated with RCHT. During a median follow-up period of 61.3 months, the median OS was 22.3 months with a 3-year OS rate of 36% (95% CI: 30– 43%) and a 3-year LC rate was 35% (95% CI:29– 41%). OS and LC varied among centers (p = 0.236 and p < 0.001), median OS and 3-year LC: C3 (23.5 months, 43%), C2 (24.1 months, 53%), C1 (15.5 months, 7%). The disease site did not affect either OS (Fig. 1) or LC (Fig. 2). Patients with RCHT had longer OS (p = 0.032, median OS of 25.5 vs. 16.6 months), but similar LC (p = 0.957). Stage-specific differences were significant for OS (p = 0.003, median 32.8, 18.3, and 14.6 months for III, IVA, and IVB, respectively). PS strongly influenced OS (p = 0.001) and LC (p = 0.033). RT regimen (normofracionation, concomitant, or simultaneous integrated boost) had no significant effect on OS (p = 0.845) or LC (p = 0.099).