ESTRO 2024 - Abstract Book

S2052

Clinical - Paediatric

ESTRO 2024

Jia Min Lim 1 , Angela Davey 1 , Simona Gaito 2 , Bernadette Brennan 3 , Frances Charlwood 2 , Lucy Davies 2 , Marinka Hol 2 , Daniel J Indelicato 4 , Daniel Saunders 2 , Ed Smith 2 , Peter Sitch 2 , Gillian Whitfield 1,2 , Marianne Aznar 1 , Shermaine Pan 2 1 The University of Manchester, Division of Cancer Sciences, Manchester, United Kingdom. 2 The Christie NHS Foundation Trust, Clinical Oncology, Manchester, United Kingdom. 3 The Royal Manchester Children's Hospital, Paediatric Oncology, Manchester, United Kingdom. 4 The University of Florida Health Proton Therapy Institute, Radiation Oncology, Jacksonville, USA

Purpose/Objective:

Advanced cancer treatment modalities such as radiation therapy have improved the long-term survival prospects among head and neck rhabdomyosarcoma (HNRMS) patients to around 66-97% (1). However, treatment-related late effects, particularly of facial deformities and asymmetry remain a concern as they can cause significant psychological sequelae. Clinically significant facial asymmetry (FA) has been reported in around 77% of children receiving radiotherapy to the head and neck (1), but dose-response relationships for facial bones are not well investigated (2).

In this study, we investigated potential factors associated with the development of FA.

Material/Methods:

We conducted a retrospective review of patients aged <16 at diagnosis with head and neck rhabdomyosarcoma treated with photon (XRT) or proton beam therapy (PBT). We had gained institutional approval to collect patients’ demographics and clinical information from the electronic documentation system. We manually delineated the dentofacial structures using an in-house atlas retrospectively (Figure 1), as this was not routinely done in clinical practice to determine the radiation dose delivered to each facial structure. The mean dose to each facial bone was extracted using Raystation and assessed against tolerances obtained from a dose effect probability curve from a separate unpublished study of 34 patients with dentofacial effects. FA was graded using Common Terminology Criteria for Adverse Events (CTCAE) version 5.0 (3) based on documented clinical assessments made during follow-up. All patients with Grade 1 and above FA were grouped as those with FA in the analyses. All responses gathered were processed for analysis and visualisation using R version 4.0.2.