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Aims: Reirradiation is becoming more frequently used in paediatric tumours of the central nervous system (CNS). To fill the void of clinical guidelines, the Swedish Working Group of Paediatric Radiotherapy compiled consensus guidelines on reirradiation in 2019. The aim of this study was to evaluate the outcome of children reirradiated for CNS tumours since implementing the guidelines.

Material and methods: All children in Sweden who were reirradiated for CNS tumours between 2019 and 2023 were retrospectively analysed. Data were collected on patient and treatment characteristics, outcome, and severe side effects. Radiation treatment plans were reviewed, and cumulative doses to organs at risk at reirradiation were extracted following rigid registration.

Results: Thirty-one patients (male 55%, female 45%) were included, and the median age at start of reirradiation was 10.2 years. The median time between primary irradiation and reirradiation was 19 months (range 2–141). The most common treatment intent at reirradiation was palliative (68%), followed by curative (32%). With a median follow-up of 8.5 months (range 0–49), the median overall survival from the end of reirradiation was 11.4 months. In the 8 patients where the treatment goal at reirradiation was symptom relief, 6 patients (75%) had relief of symptoms. The median cumulative near maximum doses (D2%) to the brain, brainstem, and chiasm/optic nerves were 71 GyEQD2 (range 44–102), 72 GyEQD2 (range 0–94), and 40 GyEQD2 (range 0–76), respectively. Following reirradiation, only 2 patients had grade ≥3 side effects. One with transient neurological deficit and one with rapid onset of blindness that persisted.

Conclusion: The implementation of national guidelines has harmonised the way paediatric patients are reirradiated for CNS tumours in Sweden. A structured follow-up shows that severe side effects are rare despite high cumulative doses to organs at risk, and that reirradiation can offer relief of symptoms and/or local control for selected patients.