Surveillance alone in stage I malignant ovarian germ cell tumors: a MITO (Multicenter Italian Trials in Ovarian cancer) prospective observational study

Objective: The aim of this study was to analyze the oncological outcome of stage I malignant ovarian germ cell tumors patients included in the MITO-9 study to identify those who might be recommended routine surveillance alone after complete surgical staging. Methods: MITO-9 was a prospective observational study analyzing data collected between January 2013 and December 2019. Three groups were identified: group A included 13 patients stage IA dysgerminoma and IAG1 immature teratoma; group B included 29 patients with stage IB-C dysgerminomas, IA-C G2-G3 immature teratomas and stage IA mixed malignant ovarian germ cell tumors and yolk sac tumors; and group C included five patients (two patients with stage IC1 and one patient with stage IC2 yolk sac tumors and two patients with mixed-stage IC2 malignant ovarian germ cell tumors). Results: A total of 47 patients with stage I conservatively treated malignant ovarian germ cell tumors were analyzed. Two patients in group B were excluded from the routine surveillance alone group due to positive surgical restaging. Therefore, a total of 45 patients were included in the study. Median follow-up was 46.2 months (range; 6-83). In total, 14 of 45 patients (31.1%) received chemotherapy, while 31 (68.9%%) underwent surveillance alone. One patient in group A, with stage IA dysgerminoma had a relapse, successfully managed with conservative surgery and chemotherapy. None of the patients in group B and C relapsed. All patients were alive at completion of the study. Overall, among 31 patients (68.9%) who underwent surveillance alone, only one patient relapsed but was treated successfully. Conclusions: Our data showed that close surveillance alone could be an alternative option to avoid adjuvant chemotherapy in properly staged IB-C dysgerminomas, IA-IC G2-G3 immature teratomas, and IA mixed malignant ovarian germ cell tumors with yolk sac tumor component.