Facial Asymmetry in Childhood Cancer Survivors Treated with Radiotherapy

Background Clinically significant facial asymmetry occurs in 77% of children treated with head-and-neck radiotherapy (HNRT) [6]. Facial asymmetry and related dentofacial side-effects are life-altering, leading to problems with eating and speech. Many children may experience a profound psychosocial impact at a critical period of personal and social development.

Presently, it is not known which children are at greater risk of developing facial asymmetry or to what extent of asymmetry will develop.

Aim We aim to understand radiation dose-response relationships in growing tissues to minimise the risks of facial asymmetry in childhood cancer survivors (CCS) by improving radiotherapy approaches to reduce dentofacial structure doses. We will develop accurate ways of evaluating asymmetry after HNRT.

We will work with young people and their parents/carers to better understand the impact of living with asymmetry and what their support needs are.

RQ1_Can a consensus-based contouring atlas with standardised nomenclature aid the delineation and understanding of dose-response relationships of dentofacial structures?

RQ2_Can radiation to dentofacial structures be further reduced in radiotherapy planning (RTP), without compromising target coverage?

RQ3_How can tools to aid clinical assessment of asymmetry be developed and how can subjective clinical assessment and objective measurements complement each other?

RQ4_What are service users and parent(s)/carer(s) perspectives on the impact of living with facial asymmetry following HNRT?

RQ5_What are the information and support needs of service users in respect of facial asymmetry risks before, during and after HNRT?

Methods This work will be undertaken in three work-packages (WPs): WP1_ Paediatric facial atlas and retrospective treatment planning study_(RQ1/RQ2) A consensus-based contouring atlas will be developed to enable dose assessment of facial structures, supporting a RTP study quantifying normal tissue dose reductions using protons and photons.

WP2_Developing clinical tools to evaluate facial asymmetry_(RQ3) Two-dimensional (2D) and 3D facial photographs will be taken of young people to develop a scale enabling standardised grading of facial anomalies post-HNRT.

We will ask participants to complete a questionnaire on perceptions of their facial asymmetry. 3D photographs will be used to derive objective measurements of asymmetry.

WP3_Utilising service users' lived experiences of facial asymmetry_(RQ4/RQ5) Individual semi-structured interviews with CCS who have undergone HNRT will be conducted to understand the impact of living with asymmetry and identify gaps in information and support needs.

Parents/carers of children with asymmetry will be invited to a focus group to understand what information they need when their child is having HNRT.

Anticipated impact Patient benefit Understanding dose-response relationships and improving RTP to minimise negative effects on healthy facial bones will minimise the risk of developing asymmetry, improving the lives of CCS.

Understanding gaps in information provision and support needs of CCS living with facial asymmetry may improve quality of life and psychological well-being. Changes to practice The atlas will provide consensus-based dentofacial contouring guidelines. The scale for evaluating facial asymmetry will simplify and standardise routine clinic assessment.

Dissemination Findings from each WP will be presented at (inter)national meetings, with full manuscripts published in peer-reviewed journals. Findings will also be disseminated to the patient and public involvement group.