Treatment Outcome of Response-based Radiotherapy in Children and Adolescents with Central Nervous System Nongerminomatous Germ Cell Tumors: Result of a Prospective Study.

PURPOSE:The optimal dose and range of radiotherapy for the central nervous system (CNS) nongerminomatous germ cell tumors (NGGCTs) have not been unified. Therefore, this study aimed to investigate the effect of individualized radiotherapy, based on the response to induction chemotherapy combined with surgery, on the prognosis of patients with NGGCT. METHODS AND MATERIALS:Based on the imaging examination and tumor markers after induction chemotherapy and pathologic results of second-look surgery, patients with NGGCT in this study received different radiotherapy strategies, including 30.6 Gy whole ventricular irradiation + tumor-bed boost to 54 Gy, 30.6 Gy craniospinal irradiation + tumor-bed boost to 54 Gy, 36 Gy craniospinal irradiation + tumor-bed boost to 54 Gy, and 36 Gy craniospinal irradiation + 54 Gy tumor-bed boost with 45 Gy to metastatic spinal lesions. RESULTS:A total of 51 patients were enrolled in this study between January 2015 and March 2021, with a median age of 10.3 years. The 3-year event-free survival (EFS) and overall survival (OS) of the entire cohort were 70.2% ± 6.9% and 77.5% ± 6.0%, respectively. The 3-year OS of patients achieving partial response after induction chemotherapy was higher than the stable disease (p = 0.03) or progressive disease group (p = 0.002). The 3-year EFS and OS of the 18 patients receiving 30.6 Gy whole ventricular irradiation and 54 Gy tumor-bed boost were 88.9% ± 7.4% and 94.4% ± 5.4%, respectively. CONCLUSION:This study suggested that an individualized radiotherapy strategy based on the response to induction chemotherapy and surgery was feasible, and promising results were still achieved after reducing the dose and extent of radiation in patients with good responses.