Endocrine Complications in Children Treated for Medulloblastoma or Ependymoma using Radiation Therapy – Outcomes in the Computed Tomography Planning Era

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Radiation therapy is an integral part of the treatment of paediatric patients with medulloblastoma and ependymoma. With newer surgical techniques and adjuvant chemotherapy regimens, recurrence-free survival rates have improved dramatically. Unfortunately, improved survival has come at the cost of significant late effects, including endocrine dysfunction. Prior to the 1990s, radiation fields were planned using 2D X-rays, exposing large volumes of healthy tissue to harmful radiation. Over the past two decades, radiation oncologists have increasingly applied 3D computed tomography scans to radiation therapy planning. By shaping target fields more precisely, higher doses of radiation may be delivered directly to the tumour while limiting exposure to healthy tissues and reducing side effects. The objective of this article is to review recent evidence about late endocrine effects among survivors of childhood medulloblastoma and ependymoma who received radiation therapy and to assess whether the introduction of 3D radiation planning techniques has affected the prevalence of these effects. Patients treated for medulloblastoma with current doses of craniospinal radiation continue to be at high risk of growth hormone deficiency and primary hypothyroidism, even when conformal radiation is used to deliver posterior fossa radiation. Patients with ependymoma who are treated with focal radiation alone, however, demonstrate fewer late endocrine effects.