ESTRO 2024 - Abstract Book

S1250

Clinical - Head & neck

ESTRO 2024

Keywords: Comorbidity, Quality of Life, ePROMs

1111

Proffered Paper

Dose-response relationship of radiation-induced trismus following head-and-neck cancer RT

Niclas Pettersson 1,2 , Nina Pauli 3,4 , Emelie Andersson 3 , Lisa Tuomi 4,5 , Caterina Finizia 3,4 , Caroline E Olsson 1,6

1 University of Gothenburg, Medical Radiation Sciences, Institute of Clinical Sciences, Sahlgrenska Academy, Gothenburg, Sweden. 2 Sahlgrenska University Hospital, Department of Medical Physics and Biomedical Engineering, Gothenburg, Sweden. 3 University of Gothenburg, Department of Otorhinolaryngology, Head and Neck Surgery, Institute of Clinical Sciences, Sahlgrenska Academy, Gothenburg, Sweden. 4 Sahlgrenska University Hospital, Department of Otorhinolaryngology, Head and Neck Surgery, Institute of Clinical Sciences, Sahlgrenska Academy, Gothenburg, Sweden. 5 University of Gothenburg, Institute of Neuroscience and Physiology, Speech and Language Pathology Unit, Gothenburg, Sweden. 6 Western Sweden Healthcare region, Regional Cancer Center West, Gothenburg, Sweden

Purpose/Objective:

Trismus is a side effect that negatively impacts the quality-of-life following radiation therapy (RT) for patients treated for head and neck cancer (HNC). In nearly all patients, it manifests during or within the first year after completed RT.

The purpose of this work was to use prospectively collected follow-up data to investigate the relationship between the absorbed dose to the masseter muscles and the risk of radiation-induced trismus following HNC RT.

Material/Methods:

This study used treatment and follow-up data from two HNC patient cohorts treated with external beam RT at the Sahlgrenska University Hospital, Sweden. Cohort 1 was treated 2007-2012 using 3DCRT, IMRT, or a combination thereof, and cohort 2 was treated 2017-2020 using VMAT. All patients underwent RT without masseter-sparing intent. Patients in cohort 1 were typically prescribed either 34x2.0 Gy or 38x1.7 Gy, and patients in cohort 2 were all prescribed 34x2.0 Gy. For each patient, the masseter muscles were consistently delineated on the planning CT images specifically for this study. The mean absorbed dose was calculated for the combination of both masseter muscles into one volume (bilateral masseter mean absorbed dose). For each patient in both cohorts, the mouth-opening ability was prospectively assessed by measuring the maximal interincisal opening (MIO). MIO was measured before start of RT (baseline) and at 3, 6 and 12 months after completed RT (follow up). We defined a patient to have experienced trismus if MIO≤35 mm at any time during follow up. Patients with MIO≤35 mm at baseline, patients treated with brachytherapy boost, patients having undergone surgery likely to affect trismus development, and patients with missing RT- or follow up data were all excluded from dose-response analysis.