ESTRO 2024 - Abstract Book

S1311

Clinical - Head & neck

ESTRO 2024

Ruta Zukauskaite 1 , Jesper G. Eriksen 2 , Jørgen Johansen 1 , Eva H. Samsøe 3 , Morte H. Kristensen 2 , Lars Johnsen 4 , Camilla K. Lonkvist 5 , Cai Grau 6 , Christian R. Hansen 4,7,6 1 Odense University Hospital, Department of oncology, Odense, Denmark. 2 Aarhus University Hospital, Department of Experimental Clinical Oncology, Aarhus, Denmark. 3 Zealand University Hospital, Department of oncology, Naestved, Denmark. 4 Odense University Hospital, Laboratory of Radiation Physics, Odense, Denmark. 5 Herlev and Gentofte Hospital, University of Copenhagen, Department of oncology, Herlev, Denmark. 6 Aarhus University Hospital, Danish Centre for Particle Therapy, Aarhus, Denmark. 7 University of Southern Denmark, Department of Clinical Research, Odense, Denmark

Purpose/Objective:

Head and neck cancer radiotherapy aims for the highest chance of cure while minimising the risk of late toxicities, like dysphagia. Many factors play an important role in this balance. Selecting appropriate margins for microscopic spread is one factor that may directly influence the local control and likewise the risk of dysphagia.

The current study investigates if different GTV to CTV margins affect the risk of dysphagia in a large cohort of consecutively treated patients.

Material/Methods:

Consecutive patients receiving primary curatively intended radiotherapy for oro-/hypopharyngeal or laryngeal squamous cell carcinoma across three national treatment centres in 2010-2015 were included. Patients underwent definitive IMRT-based treatment according to two specific DAHANCA guidelines. During 2010-2012, the GTV-CTV1 margins were heterogeneous and centre-dependent, with GTV to high-dose CTV (CTV1) margins varying from 0-10 mm, or anatomically defined (1). In 2013, the national DAHANCA radiotherapy guidelines were revised, and a homogenous isotropic geometrical 5 mm margin was implemented at the centres (2). In the current study, all DICOM treatment plans were retrospectively collected, and the GTV-CTV1 margins were quantitatively assessed by calculating the median surface distance from the primary GTV to CTV1. Clinical parameters were prospectively collected. The follow-up was every six months after treatment completion for the first two years and once a year for the next three years. Next to the objective examination, the patients were assessed for dysphagia. The scoring was modified LENTSOMA scale: 0: no dysphagia; 1: symptomatic, able to eat regular diet; 2: symptomatic and altered eating/swallowing, soft food; 3: symptomatic and altered eating/swallowing, only fluid food; 4: severely altered eating/swallowing; tube feeding or hospitalisation; urgent intervention indicated. Dysphagia scores at 6 and 12-month follow-up with a two-month window were used for the present study. Ordinal logistic regression analyses was performed to identify predictors for risk of dysphagia, including sex, smoking status, tumour site, use of radiosensitizer, chemotherapy, as well as GTV volume (log-transformed) and GTV-CTV1 margin (in millimetres).

Results: