Defining the role of proton therapy in the optimal management of paediatric patients in Australia and New Zealand.

Abstract

Optimal management of paediatric patients with tumours may include radiation therapy. Proton therapy, in theory, should achieve superior outcomes. For children referred overseas, multiple factors are taken into consideration. The purpose of this article is to provide context to current decision making. The MEDLINE, EMBASE and PubMed databases were searched for relevant literature. The delivery of proton therapy is in evolution. Tissue homogeneity, movement and anatomical changes all present a greater challenge for proton therapy compared with photon therapy. Many dosimetry studies are relying on historical data for cost-benefit analyses that do not accurately reflect contemporary photon therapy. The low dose regions generally do not create significant toxicity, whereas moderate dose regions can be reduced by different techniques such as stereotactic radiotherapy and brachytherapy. Neuro-cognitive and neuro-endocrine toxicities are associated with the greatest health cost, so the greatest gain is for tumours within or abutting the central nervous system. Proton therapy does not eliminate the risk of second malignancy. The benefits of proton therapy must be weighed against not just the estimated impact of low and moderate radiation doses on the developing child but the disruptions to the child, and family life. Relative contraindications to proton therapy include when the relevant late toxicities relate to the high radiation dose region, when the tumour volumes encompass whole body sections and when the target is imprecise. Children with base of skull tumours or an inherited risk of cancer (e.g. those with p53 or Rb1 genes) should be considered for proton therapy.