PEDT-6 A RANDOMIZED CONTROLLED CLINICAL STUDY OF RADIOTHERAPY COMBINED WITH CHEMOTHERAPY IN PATIENTS WITH NEWLY DIAGNOSED CENTRAL NERVOUS SYSTEM GERM CELL TUMOR, JCCG CNSGCT2021

BACKGROUND: Central nervous system (CNS) germ cell tumors account for 15.3% of all CNS tumors in children and adolescents and young adults. Five histologic types and mixed types exist and can be classified into the following clinical risk groups: germinomas, malignant germ cell tumors, and other germ cell tumors. In germinomas, platinum-based chemotherapy and whole ventricle/brain irradiations 23.4 Gy/13 fraction are the standard of care, but late adverse events related to radiation therapy are a problem. In malignant germ cell tumors, chemotherapy with alkylating agents and platinum, craniospinal irradiation (CSI), and local radiation therapy (local dose 50-59.4 Gy/25-33 fractions) have become the standard of care, but the 10-year OS is poor at about 60% and late radiation therapy-related adverse events are an issue. For various reasons, it is not easy to establish a standard of care for mature teratomas and immature teratomas, which constitute the other germ cell tumors, but it is essential to collect knowledge on tumor characteristics and prognosis. METHODS AND PATIENTS: The Japan Children's Cancer Group Brain Tumor Committee has planned a study to validate the classification by histological diagnosis and ancillary tumor markers, a phase III study to test the non-inferiority of radiation dose reduction to standard therapy for germinomas, a phase II study to test the superiority of high-dose chemoradiation with methotrexate intrathecal injection excluding CSI to standard therapy for malignant germ cell tumors, observational studies to elucidate pathogenesis of other germ cell tumors. DISCUSSION: If these hypotheses are proven, it is expected to reduce late adverse events and prolong survival with radiotherapy in children and adolescent/young adult generation patients.