Re-irradiation for Paediatric Tumours.

Despite best available therapy, many children with cancer develop recurrence after multimodal treatment, including initial radiation therapy. Re-irradiation is defined as the use of a second course of radiation therapy with a retreatment volume that overlaps substantially with that of a previously delivered course of radiation therapy. Re-irradiation is an important part of salvage treatment for patients with recurrent ependymoma, diffuse intrinsic pontine glioma, medulloblastoma and germinoma. In patients with ependymoma, conventionally fractionated re-irradiation (1.8 Gy/day) can provide long-term disease control with low rates of high-grade toxicity. For children with progressive diffuse intrinsic pontine glioma, re-irradiation provides effective palliation of symptoms and a survival gain as compared with those treated without re-irradiation. Repeat radiation therapy that includes craniospinal irradiation, if safe to deliver, may provide long-term tumour control in patients with medulloblastoma. Patients with recurrent intracranial germinoma can be effectively salvaged with re-irradiation that includes craniospinal irradiation. Finally, the emerging role of re-irradiation in non-brainstem high-grade glioma and extracranial solid tumours requires further study regarding its efficacy and safety. When given, re-irradiation should be delivered with care so that doses to organs at risk are minimised. In all cases, re-irradiation should be considered as an option alongside, or concurrently with, other salvage treatments, including surgery or systemic therapy, to maximise the likelihood of durable disease control.