ESTRO 2025 - Abstract Book

S1050

Clinical – Head & neck

ESTRO 2025

Table 2. Multivariate Analysis of overall survival, disease-free survival, locoregional control, and distant control for pre-ALC, mid-ALC, and ∆-ALC, with concordant C-indices.

Conclusion: We demonstrate for a homogenous group of patients with HPV-associated OPC receiving CRT that although various lymphocyte characteristics are prognostic, the pre-ALC is generally most significantly associated with outcomes. This supports the potential use of pre-ALC to risk-stratify patients for treatment[1–4]. Of note, ∆-ALC was found to be most prognostic for locoregional control, which may reflect a correlation with disease and treatment received, although ∆-ALC remained significant on multivariate analysis. Lymphocyte kinetics may offer additional value early in treatment to predict likely outcomes. References: [1] Huang SH et al. Prognostic value of pretreatment circulating neutrophils, monocytes, and lymphocytes in oropharyngeal cancer stratified by human papillomavirus status. Cancer 2015;121:545–55. [2] Ward MJ et al. Tumour-infiltrating lymphocytes predict for outcome in HPV-positive oropharyngeal cancer. Br J Cancer 2014;110:489–500. [3] Price JM et al. Pretreatment Lymphocyte Count Predicts Benefit From Concurrent Chemotherapy With Radiotherapy in Oropharyngeal Cancer. Journal of Clinical Oncology 2022;40:2203–12. [4] Kreinbrink PJ et al. Pre-treatment absolute lymphocyte count predicts for improved survival in human papillomavirus (HPV)-driven oropharyngeal squamous cell carcinoma. Oral Oncol 2021;116. Keywords: lymphocytes, chemoradiotherapy, oropharynx

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Digital Poster Survival outcomes of HPV-negative Head and Neck cancer patients treated by definitive radiotherapy or radiochemotherapy: data from three centers. Marek Slavik 1,2 , Jakub Cvek 3 , Iveta Selingerova 4 , Jan Cincibuch 5 , Lukas Knybel 3 , Tomas Novotny 1 , Petr Burkon 1,2 , Miroslava Slavikova 1 , Pavel Slampa 1,2 , Tomas Kazda 1,2 , Martin Dolezel 5 1 Department of Radiation Oncology, Masaryk Memorial Cancer Institute, Brno, Czech Republic. 2 Department of Radiation Oncology, Faculty of Medicine, Masaryk University, Brno, Czech Republic. 3 Department of Oncology, Faculty of Medicine and University Hospital, Ostrava, Czech Republic. 4 Department of Clinical Trials, Masaryk Memorial Cancer Institute, Brno, Czech Republic. 5 Department of Oncology, Faculty of Medicine and University Hospital, Olomouc, Czech Republic

Purpose/Objective: This study retrospectively evaluates treatment outcomes of patients with squamous cell head and neck cancers