ESTRO 2025 - Abstract Book

S1134

Clinical – Head & neck

ESTRO 2025

4367

Digital Poster Impact of active smoking on early survival and acute severe toxicities of patients treated with radiotherapy for head and neck cancer. Louis Munschi 1 , Esteban Brenet 2 , Coralie Barbe 3 , Leila Bouazzi 3 , Camille Invernizzi 1 , Arnaud Beddok 1 1 Radiotherapy, Institut Godinot, Reims, France. 2 Otorhinolaryngology, Robert Debre Hospital Center, Reims, France. 3 Methodology and Biostatistics Units, Reims-Champagne-Ardenne University, Reims, France Purpose/Objective: The relationship between smoking and the survival outcomes of patients undergoing treatment for head and neck cancers remains ambiguous. The aim of this study was to evaluate the overall survival (OS) of active smoking versus non-smoking patients treated with radiation therapy (RT) for head and neck cancers (HNC). Material/Methods: This prospective observational cohort study, conducted at a single center, included patients with HNC treated with RT with or without chemotherapy. Patients receiving definitive RT were treated with a total dose of 70 Gy delivered in 33 to 35 fractions, while those undergoing postoperative RT received a total dose of 66 Gy in 33 fractions. Radiotherapy was administered once daily, five days per week, using either helical TomoTherapy or Volumetric Modulated Arc Therapy. Smoking status (active versus former or never smoker) was determined at the time of inclusion and reassessed weekly during the treatment period. The primary outcome measure was OS at 18 months. Secondary endpoints included progression-free survival (PFS) at 18 months, loco-regional control at 3 months, and the occurrence of at least one grade ≥ 3 acute toxicity among mucositis, dysphagia and dermatitis. Results: A total of 102 patients were included (63.1 ±8.9 years; 73.6% male), of whom 27.4% were active smokers. Among them, 53 patients (52.0%) had surgery, of whom 15 (14.7%) received adjuvant RT alone, and 38 (37.2%) received concomitant chemotherapy. Among non-operated patients, RT was administered alone in 5.9% of cases (n=6), and with concomitant chemotherapy in 42.2% of cases (n=43). The OS rate at 18 months was 67.7%, with no difference between active smokers and non-smokers (p=0.30). The PFS rate at 18 months was significantly lower among active smokers (39.6% versus 62.7%; p=0.03), and this association remained significant after adjusting for confounding factors: age, BMI, alcohol consumption, and ECOG status (adjusted HR 1.91; 95% CI 1.01-3.59; p=0.04). Active smoking did not influence loco-regional control at 3 months (p=0.23). Considering severe acute toxicity, 23.3% (n=24) patients experienced a severe mucositis, 36.9% (n=38) a severe dysphagia, 13.6% (n=14) a severe dermatitis and 54.4% (n=56) experienced at least one of them. Occurrence of severe acute toxicity was not statistically associated with smoking during radiotherapy (62.1% among active smokers versus 51.3% among non-active smokers; p=0.33).