ESTRO 2024 - Abstract Book

S2021

Clinical - Paediatric

ESTRO 2024

555

Poster Discussion

Re-irradiation in paediatric CNS-tumours: Outcome after implementing national guidelines

Anna Embring 1,2 , Anna Asklid 1 , Malin Blomstrand 3 , Charlotta Fröjd 3 , Martin P. Nilsson 4 , Ingrid Fagerstöm Kristensen 4 , Måns Agrup 5 , Anna-Maja Svärd 6 , Ulla Martinsson 7 , Anna Flejmer 7 , Jacob Engellau 4 1 Karolinska University Hospital, Department of Radiotherapy, Stockholm, Sweden. 2 Karolinska Institute, Department of Oncology-Pathology, Stockholm, Sweden. 3 Sahlgrenska University Hospital, Department of Oncology, Gothenburg, Sweden. 4 Skåne University Hospital, Department of Hematology, Oncology and Radiation Physics, Lund, Sweden. 5 Linköping University, Department of Oncology, and Department of Biomedical and Clinical Sciences, Linköping, Sweden. 6 Umeå University, Department of Radiation Sciences, Umeå, Sweden. 7 Uppsala University, Department of Immunology, Genetics and Pathology, Uppsala, Sweden

Purpose/Objective:

Re-irradiation in paediatric tumours of the central nervous system (CNS) is becoming a more frequently used treatment option. To fill the void of clinical guidelines, the Swedish Workgroup of Paediatric Radiotherapy compiled national consensus guidelines in 2019, which were recently published [1]. The aim of this study is to evaluate the outcome of children treated with re-irradiation for a CNS-tumour since implementing the guidelines.

Material/Methods:

Twenty-six children re-irradiated for CNS-tumours between 2019-2023 in Sweden were retrospectively analysed. A review of medical records was done to collect data on severe side effects, treatment effect, survival, and clinical and treatment characteristics.

Results:

A total of 26 patients, 14 male (54%) and 12 female (46%), were analysed and the median age at start of re irradiation was 10.1 years (range 3.7-18.8). The median overall survival was 13.6 months (Figure 1). The median follow-up was 8.4 months (range 0-44). Eleven patients (42%) were still alive at closure of database. The most common diagnosis at re-irradiation was diffuse intrinsic pontine glioma or midline glioma (n=10), followed by ependymoma (n=6), medulloblastoma (n=3) and high-grade gliomas (n=3). The median time between irradiations was 11 months (range 2-74). The vast majority (92%) were type 1 re-irradiations according to Andratschke et al.[2]. The most common treatment intent at re-irradiation was palliative (58%), followed by curative (38%) and local ablative (4%). In the 13 patients where the intention was palliative, 8 (73%) had relief of symptoms after re irradiation. The majority (73%) of the included patients were evaluated radiologically after the re-irradiation and this showed complete response in 2 patients (8%), partial response in 7 patients (27%), stable disease in 8 patients (31%) and progressive disease in 2 patients (8%). The most common fractionation schedule at re-irradiation was 20 Gy in 10 fractions (n=9, 35%) followed by 54 Gy in 30 fractions (n=3, 12%). The most common radiotherapy modality at re-irradiation was photon treatment (n=15, 58%), followed by proton treatment (n=10, 38%) and 1 patient (4%) was treated with gammaknife. Five patients (19%) had craniospinal irradiation at re-irradiation. The median size of the PTV-volume of the non-CSI re-irradiations was 78 cc (range 1-2101). Out of the re-irradiated patients only 2 had acute grade ≥3 side effects. One developed weakness in his arm 2 months after re-irradiation