10136-CS-12 Efficacy and Safety of Reduced-Dose Radiotherapy and Intensified Chemotherapy for Intracranial Germ Cell Tumors

Abstract Background and Objective While the efficacy of chemoradiotherapy for intracranial germ cell tumors is established, recent approaches focus on reducing late complications and optimizing treatment intensity by lowering radiation doses and intensifying chemotherapy. From 1978 to 2014, our institution treated germ cell tumors (excluding yolk sac tumor and choriocarcinoma) with carboplatin (CBDCA) and etoposide (VP-16) plus 30 Gy whole ventricular irradiation, achieving 5-year PFS rates of 91.4% for germinoma and 77.2% for non-germinoma, and OS rates of 97.1% and 78.9%, respectively. Since 2014, we reduced radiation to 25.2 Gy and added ifosfamide (IFO) to CBDCA+VP-16 to further reduce late complications. This study retrospectively evaluated outcomes of this new protocol. Methods We retrospectively analyzed 41 patients with newly diagnosed primary intracranial germ cell tumors from April 2014 to August 2022: 24 germinomas, 13 intermediate prognosis non-germinomas, and 4 poor prognosis (yolk sac tumor/choriocarcinoma). All underwent surgery followed by IFO+CBDCA+VP-16 chemotherapy and radiotherapy. Germinoma/intermediate prognosis groups received 25.2 Gy whole ventricular (or whole brain for basal ganglia tumors) irradiation; poor prognosis group received 30.6 Gy craniospinal irradiation. Local boosts were added as needed. Results The 5-year PFS was 95.8% for germinoma, 84.6% for intermediate prognosis, and 75.0% for poor prognosis groups. All groups had a 5-year OS of 100%. Grade 3 or higher hematologic toxicity occurred in 75.6%, but no treatment-related deaths. Myelosuppression was enhanced after radiotherapy but manageable in all cases. Conclusion These findings suggest that reducing radiation while intensifying chemotherapy with IFO may improve survival and reduce late adverse effects.