AGE AND DOSIMETRIC IMPACTS ON RADIOTHERAPY ASSOCIATED GROWTH IMPAIRMENT FOR PATIENTS WITH INTRACRANIAL GERM CELL TUMORS (GCTS)

Abstract PURPOSE Intracranial germ cell tumors (GCTs) are rare pediatric central nervous system (CNS) tumors. Growth impairment induced by radiation treatments was rarely evaluated. We aimed to study the impacts of radiotherapy on height development and identify the dosimetric constraints. MATERIALS AND METHODS A total of 148 pediatric patients diagnosed with GCTs were retrospectively analyzed. Sex, age at irradiation, physical doses and biologically effective dose (BED), height, and endocrine status were obtained from patient records. The cumulative change in height was assessed using age-matched normalized height (ANH). Variables were assessed for correlations and statistical significance. RESULTS Cumulative physical doses and BEDs for the whole brain and pituitary were derived via DVHs and BEDVHs. In contrast to patients >11.5 yr, linear correlations between ANH and cumulative physical doses as well as BEDs to the whole brain and pituitary were identified in patients≤11.5 yr. Dosimetric constrains to the pituitary was 36 Gy for physical dose (AUC=0.70 [95% CI, 0.54-0.86], P< 0.05) and 63 Gy2 BED (AUC=0.69 [95% CI, 0.53-0.86], P< 0.05). Intriguingly, no significant differences in ANH were found among different CSI dose groups in patients ≤11.5 yr. (all P>0.05). Impaired hormone secretions in terms of GH and TSH were identified following cranial irradiation (both P< 0.001), particularly for those with tumors at the suprasellar region (GH: P< 0.01, TSH: P< 0.001). CONCLUSION Our study revealed the impacts of age, dosimetrics and tumor locations for growth impairment. This study will contribute to the optimization of radiation treatment planning and facilitate more individualized therapeutic strategies in pediatric patient with GCTs.