S569
Clinical – Head & neck
ESTRO 2026
multidisciplinary treatment planning. Prospective multicenter validation using harmonized DWI protocols is warranted to confirm reproducibility and facilitate clinical translation. Keywords: Salivary gland carcinoma Digital Poster Highlight 1555 Correlation of post-treatment PET-CT response scores with oncologic outcomes in HNSCC: comparison of the Hopkins and Christie criteria Mohamed Mortada Elsharief 1,2 , Nathan Baguley 3 , Suzie Bonington 3 , Anubhav Dhatta 3 , Kate Garcez 4 , Christopher Hughes 4 , Lip Wai Lee 4 , David Thomson 4 , James Price 4 1 The Christie PBT centre, The Christie NHS Foundation Trust, Manchester, United Kingdom. 2 Radiation Oncology, National Cancer Institute, Cairo, Egypt. 3 Radiology department, The Christie NHS Foundation Trust, Manchester, United Kingdom. 4 Clinical Oncology department, The Christie NHS Foundation Trust, Manchester, United Kingdom
Results: Median age was 61 years (IQR 55–68); 77% were male. The oropharynx was the most common subsite (60%), followed by hypopharynx (14%) and larynx (10%). Concomitant chemotherapy was delivered to 62% (cisplatin 46%, carboplatin 14%, cetuximab 1%).Higher Hopkins and Christie scores were significantly associated with worse outcomes. For OS, adjusted HRs per one-level increase were 1.41 (95% CI 1.19–1.65, p < 0.001) and 1.69 (1.29–2.23, p < 0.001), respectively. For PFS, adjusted HRs were 1.59 (1.35–1.86, p < 0.001) and 1.96 (1.51–2.56, p < 0.001). For LRFS, adjusted HRs were 2.94 (2.17–3.97, p < 0.001) and 3.96 (2.51–6.25, p < 0.001) (Figure). Discrimination was good, with C- indices of 0.63/0.62 for OS, 0.66/0.64 for PFS, and 0.80/0.76 for LRFS (Hopkins/Christie scores, respectively).
Purpose/Objective: 18F-FDG PET-CT is the mainstay of post-
(chemo)radiotherapy response assessment in head and neck squamous cell carcinoma (HNSCC), yet interpretation remains challenging, due to equivocal FDG uptake in treated areas. The Hopkins 5-point qualitative score is widely used, while the Christie 3- point score was developed locally to simplify reporting and improve reproducibility. We evaluated the prognostic value of both scoring systems in predicting survival outcomes and quantified their discriminative performance. Material/Methods: This retrospective study included 291 patients with HNSCC treated with definitive radiotherapy ± chemotherapy between September 2017 and December 2020 at a UK tertiary centre. The Hopkins (1–5) and Christie (1–3) scores were recorded from the first post-treatment PET-CT scan (median ~12 weeks). Endpoints were overall survival (OS), progression-free survival (PFS), and locoregional relapse-free survival (LRFS). Kaplan–Meier estimates were compared using log-rank tests. Univariable and multivariable Cox models were used to estimate hazard ratios (HR) per one-level increase in score, adjusted for age, sex, primary site, T-stage, N-stage, and chemotherapy regimen. Discrimination was assessed using Harrell’s C-index (0.5 = random; 1.0 = perfect).
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