Guidelines for Complications of Cancer Treatment Vol VIII Part B

RT to brain has been implicated as one of the mostimportant factor associated with neuroendocrinedysfunction after long term follow up.Radiation dose and volume of brain irradiated had shownsignificant correlation. Majority of the literature hascome from either craniospinal radiation (CSI) or fromwhole brain RT.Both in whole brain RT and CSI, PHA receives highdose and thus functional impairment is expected evenyears after RT. Growth hormone (GH) seems to be themost sensitive hormone as it’s serum level is the first todecline after RT. GH is followed by thyroid hormonereleasing hormone (THRH) and cortisol level decline.Impairment of the circadian hormonal surge is consideredas an early sign of hormone axis deficit.Frequency, delay of appearance and severity ofdeficiency depends upon RT dose delivered, age of thepatient and treatment schedule.After conventional whole brain RT (WBRT) with dosemore than 18 Gy, impairment of normal growth hormone(GH) secretion are the first and most common recognizeddeficit.After CSI, 50% to 80% of patients develop signs of GHdeficiency, 30-50% develops primary hypothyroidismand 30-40% develops cortisol deficiency.Functional disturbances of thyroid and adrenal glandsdue to PH axis deficiency are less common and usuallyseen only after RT dose >40 Gy.Few chemotherapeutic regimens used in brain tumor arealso associated with decline in endocrine function.Patients with hormonal dysfunction presents with earlyor delayed puberty or growth retardation. Girls mayfrequently experience an early and rapid pubertal350