ESTRO 2022 - Abstract Book

S429

Abstract book

ESTRO 2022

Conclusion This is the first population-based prospective cohort study investigating ULCER 1-year among OPC patients treated with curative intent. IMPT is not associated with an increased risk of radiation ulcers compared to photons. The most important risk factors for ULCER 1-year are: T3-T4; ulcerative/exophytic growth pattern, smoking during RT and co-morbidity. Although often considered dose limiting, most ulcers recover with conservative treatment measures.

MO-0479 Hypofractionation and the risk of post radiation mucosal ulcers in oropharyngeal carcinoma.

G. Verduijn 1 , S. Petit 2 , N. Sijtsema 2 , I. Lauwers 2 , Y. van Norden 2 , A. Sewnaik 3 , R. Nout 1 , A. van der Lugt 4 , M. Hoogeman 1 , W. Heemsbergen 5 1 Erasmus MC Cancer Institute, Radiation Oncology, Rotterdam, The Netherlands; 2 Erasmus MC Cancer Institute , Radiation Oncology, Rotterdam, The Netherlands; 3 Erasmus MC, Otorhinolaryngology and Head and Neck surgery, Rotterdam, The Netherlands; 4 Erasmus MC , Radiology, Rotterdam, The Netherlands; 5 Erasmus MC Cancer Institute, Radiation oncology, Rotterdam, The Netherlands Purpose or Objective Post radiation mucosal ulcers (PRMU) can have a huge negative impact on quality of life in patients with oropharyngeal squamous cell carcinoma (OPSCC). However, information on risk factors, and in particular on the impact of hypofractionation, is scarce. Therefore, the goal of this study was to determine the pattern of late PRMU development and to identify risk factors after hypofractionated and conventional radiotherapy for OPSCC. Materials and Methods We performed a retrospective cohort study in 332 consecutive OPSCC patients with cT1-T4N0-N3M0 disease. Patients were included who survived at least one year after treatment with curative intent between January 2009 and June 2016. Patients were treated using: 1) conventional IMRT (70 Gy in 2 Gy fractions), or 2) IMRT (46 Gy in 2 Gy fractions) followed by a hypofractionated stereotactic body radiotherapy (SBRT) boost (16.5 Gy in 5.5 Gy fractions). Grade ≥ 2 PRMU (i.e. symptomatic PRMU according to CTCAE v5.0) was scored in case one or more ulcers were observed > 3 months after the last RT fraction. Two types of PRMU were distinguished: late PRMU arising several months after RT and PRMU directly