ESTRO 2024 - Abstract Book

S2054

Clinical - Paediatric

ESTRO 2024

Figure 2 : Absolute difference between left and right doses (Gy) across various structures, categorised by presence or absence of facial asymmetry

Fifteen patients, six male and nine female, were included in the final analyses. The median follow-up time was 5.1 (1.4 - 12.5) years. The median age was 8.7 (3.2 to 15.5) years at treatment and 14.2 (4.8 to 17.3) years at follow-up. Eleven patients were treated with PBT and four with XRT. Of the fifteen patients evaluated, eleven (73%) developed facial asymmetry post-treatment. Four had Grade 1, and the remaining seven had Grade 2. There was no report of any facial asymmetry in the other four patients, three treated with PBT and one with XRT. There was a statistically significant difference in the median age between those with and without FA (p=0.018). Patients with FA were aged 5.8 (range: 3.2 – 13.4) years, and those without FA were 11.4 (range: 9.1 – 15.5) years. On a univariable logistic regression model, age at treatment was borderline significant (p=0.061) with odds-ratio of 0.58. All other clinical variables, including treatment modality, tumour laterality, gender, tumour site and absolute dose difference across structures, demonstrated no significant association with FA on univariable modelling. There was no statistically significant difference in mean dose to whole structures for those with and without asymmetry (Table 1). Whilst tumour laterality and location resulted in varied dose distribution to specific structures, this was not found to be a significant factor in statistical analysis. Notably, cases with asymmetry tended to have a greater absolute difference in dose to the facial structures (Figure 2). Among the eleven patients who received PBT, eight (72%) reported FA, and three out of four patients (75%) who received XRT had FA; this was not statistically significant (p>0.9).

Conclusion:

Age at treatment is likely a contributory factor in the development of FA in children with HNRMS treated with XRT or PBT. Further studies with larger patient cohorts are needed to better understand which patients are most at risk of developing asymmetry.

Keywords: facial asymmetry, radiotherapy, rhabdomyosarcoma

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