Prognosis and risk factors by histologic type of malignant ovarian germ cell tumors in Japan: a JSOG gynecologic tumor registry-based study.

OBJECTIVE: This study evaluated prognosis and risk factors for overall survival (OS) in malignant ovarian germ cell tumors (MOGCTs) using data from the Japan Society of Obstetrics and Gynecology tumor registry. METHODS: Data from 1,538 MOGCT patients (2004-2019) were retrospectively analyzed. Factors such as age, International Federation of Gynecology and Obstetrics (FIGO) stage, histologic subtype, lymph node status, and surgical outcomes were examined. Kaplan-Meier curves and Cox proportional hazards regression analyses were used to assess OS. RESULTS: The histologic distribution was immature teratoma (56.6%), yolk sac tumor (28.7%), dysgerminoma (10.0%), and mixed germ cell tumor (9.6%). The 5-year OS rate was 94.8% overall, with the highest OS in dysgerminoma (97.4%) and the lowest in mixed germ cell tumors (87.2%). Advanced FIGO stage and incomplete surgical resection were significant predictors of poorer OS across subtypes. Age ≥50 years was independently associated with poorer OS in yolk sac tumor, immature teratoma grade 3, and mixed germ cell tumor. Although favorable survival outcomes were observed in patients with advanced-stage yolk sac tumors, the present registry-based study was not designed to evaluate the impact of specific chemotherapy regimens. CONCLUSION: MOGCTs demonstrate favorable survival outcomes in Japan. However, advanced FIGO stage, incomplete surgical resection, and older age were significant risk factors for poorer OS in specific subtypes. The observed survival patterns may reflect contemporary multidisciplinary management, but definitive conclusions regarding specific chemotherapy regimens cannot be drawn from this registry-based analysis.