The Predictive Value of Insulin-Like Growth Factor 1 in Irradiation-Dependent Growth Hormone Deficiency in Childhood Cancer Survivors

The literature contains conflicting reports on the value of low insulin-like growth factor 1 (IGF-1) levels in predicting radiation-induced growth hormone (GH) deficiency (GHD) in childhood cancer survivors (CCS). These reports often involve small samples of patients who have received irradiation or mixed cohorts including non-irradiated subjects. Objective: We undertook an analysis of the predictive value of low IGF-1 in CCS at risk for GHD after cranial radiotherapy involving the hypothalamic-pituitary (HP) area in a large single-centre cohort. Methods: We performed a retrospective analysis on 158 CCS diagnosed with GHD between January 1, 2003 and October 31, 2017 and identified 117 patients who received radiation for tumours not directly involving the HP area. Results: In this cohort, IGF-1 levels -2 standard deviation scores (SDS) had a sensitivity of 31.9% for GHD; however, they were statistically more frequent (p = 0.0023) and had a higher sensitivity (45.6%) among patients with severe GHD. At final height reassessment, IGF-1 -2 SDS had a sensitivity of 35.0% for GHD, but a positive predictive value of 100%. Finally, pretreatment IGF-1 values showed no correlation with the number of impaired pituitary hormonal axes in patients with multiple pituitary deficiencies. Conclusions: IGF-1 levels -2 SDS showed a low sensitivity at predicting radiation-induced GHD both in childhood and in adulthood, but a high positive predictive value for GH status at final height reassessment.