ESTRO 2025 - Abstract Book

S942

Clinical – Head & neck

ESTRO 2025

Two-year overall survival was 64% after primary surgery, 55% after primary radiotherapy, 87% after complete response to radiotherapy, and 92% in complete responders who were p16+. Median OS was not reached for surgery versus 38 months for radiotherapy, hazard ratio 1.66 (p=0.262). Median OS was 91 months for complete responders after radiotherapy, hazard ratio 0.62 versus surgery (p=0.423). Median OS was not reached for p16+ complete responders after radiotherapy, hazard ratio 0.34 versus surgery (p=0.187).

Response assessment was with PET-CT in 77% of patients and predicted subsequent disease-free survival better than CT. None of the fifteen p16+ patients treated with primary radiotherapy had residual disease on their post treatment scan. p16+ patients were more likely to achieve complete response, but extracapsular spread was not predictive of response. Conclusion: Our cohort of N3 HNSCC is among the largest in the literature, with long follow-up duration. The non-significant trend to benefit with surgery may have arisen due to baseline imbalances. Surveillance after complete response on post-radiotherapy PET-CT leads to good outcomes for p16+ patients, sparing them the morbidity of neck dissection. p16- patients may benefit from primary surgery.

Keywords: chemoradiation, neck dissection, watch and wait

References: 1. Brizel DM, Prosnitz RG, Hunter S, et al. Necessity for adjuvant neck dissection in setting of concurrent chemoradiation for advanced head-and-neck cancer. Int J Radiat Oncol Biol Phys 2004;58(5):1418-23. DOI: 10.1016/j.ijrobp.2003.09.004. 2. Mehanna H, Wong W-L, McConkey CC, et al. PET-CT Surveillance versus Neck Dissection in Advanced Head and Neck Cancer. New England Journal of Medicine 2016;374(15):1444-1454. DOI: 10.1056/NEJMoa1514493.

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Digital Poster Definitive hypofractionated radiotherapy of head and neck squamous cell carcinoma (HNSCC) in frail and elderly patients Petra Štefková 1 , Pavol Dubinský 1,2 , Vladimír Vojtek 1 1 Department of Radiation Oncology, East Slovakia Institute of Oncology, Košice, Slovakia. 2 Faculty of Health, Catholic University in Ružomberok, Ružomberok, Slovakia