Proton therapy for paediatric CNS tumours - improving treatment-related outcomes

Radiotherapy is an integral and highly effective aspect of the management of many paediatric CNS tumours, including embryonal tumours, astrocytic tumours and ependymal tumours. Nevertheless, continued improvements in long-term survivorship of such tumours means that radiotherapy-related toxicities that affect quality of life and overall functional status for survivors are increasingly problematic, and strategies that mitigate these adverse effects are needed. One such strategy is proton therapy, which has distinct advantages over conventional photon therapy and enables greater precision in the delivery of tumoricidal radiation doses with reduced irradiation of healthy tissues. These dose distribution advantages can translate into clinical benefits by reducing the risk of long-term adverse effects of radiotherapy, such as secondary malignancy, cognitive toxicity, endocrinopathy, hearing loss and vasculopathic effects. As the availability of proton therapy increases with the development of new proton centres, this treatment modality is increasingly being used in the management of paediatric CNS tumours. In this Review, we provide an introduction to the types of paediatric CNS tumours for which proton therapy can be considered, and discuss the available evidence that proton therapy limits toxicities and improves quality of life for patients. We will also consider uncertainties surrounding the use of proton therapy, evidence for its cost-effectiveness, and its future role in the management of paediatric CNS tumours.