[Treatment of CNS Germ Cell Tumors]

Central nervous system (CNS) germ cell tumors (GCTs) are rare neoplasms that predominantly affect adolescents and young adults and occur at a notably higher incidence in East Asian populations. They are classified into two major categories: germinomas and non-germinomatous GCTs (NGGCTs). Germinomas are highly radiosensitive and chemosensitive, with long-term survival rates exceeding 90% following combined chemoradiotherapy. Current therapeutic focus on reducing radiation exposure, particularly whole-ventricular irradiation, while maintaining excellent tumor control, as exemplified by the ongoing CNSGCT2021 trial in Japan. In contrast, NGGCTs require intensified multimodal treatment incorporating alkylating-agent-based chemotherapy and craniospinal irradiation, and second-look surgery for residual disease. Despite these advances, outcomes for relapsed NGGCTs remain poor, underscoring the urgent need for novel therapeutic approaches. Recent genomic studies have identified recurrent activating mutations in the KIT/RAS/MAPK and PI3K/AKT/mTOR pathways, particularly in germinomas, providing potential targets for precision oncology approaches. The germinoma tumor microenvironment is characterized by abundant immune infiltration and PD-L1 expression, which has generated interest in immune checkpoint inhibitors. Additionally, liquid biopsy biomarkers, including circulating tumor DNA and microRNAs, show promise for less invasive diagnosis and disease monitoring. Long-term follow-up remains essential, given the risk of late relapse beyond 10 years and accumulation of treatment-related complications over decades.