GH deficiency after treatment of medulloblastoma and thyroid cancer: is this the case for GH therapy?
Z. Valkusz, S. Magony, K. Sepp, E. Csajbok, J. Julesz & L. Pavics
The hypothalamicpituitary unit is a particularly radiosensitive region in the central nervous system. As a consequence, hypopituitarism commonly develops after radiation treatments for sellar and parasellar neoplasms, extrasellar brain tumours. Increasing tumour-related survival rates provide an expanding population at risk of developing hypopituitarism. The severity of hypopituitarism is related to the radiation doses given while whole body irradiation regimens to a dose of 18 Gy result merely in isolated GH deficiency. Somatotrophs are reported to be more radiosensitive in children as compared with adults: 59% of childhood cancer survivors show a blunted response on GH stimulatory tests. GH has consistently shown to be the most radiosensitive pituitary axis, with series reporting a prevalence of GHD between 50 and 100% after radiotherapy. Radiation-induced GHD is also progressive with time, developing more frequently in the first 10 years after radiation delivery. GHD severity and speed of onset closely correlate with lower final height, decreased lean body mass (LBM) and higher fat mass in children. There are several data indicating the significance of radiotherapy as a risk factor for hypothyroidism.
Children with malignancy treated with chemotherapy and radiation to the head, neck and mediastinum are at risk of developing hypothyroidism and thus should be monitored with regular thyroid function test surveillance up to around 10 years post-diagnosis. A 20 years old female patients case is presented: after successful treatment of medulloblastoma at the age of 6, she was operated and treated with radioiodine for papillary type of thyroid cancer in her 15 years of age. As a consequence of her previous diseases and treatments last year we detect a severe GH deficiency. We show how is she currently managed.
Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.
Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.