Primary mediastinal germ cell tumors ‐ A retrospective analysis of >30 years of experience in a single institution

BACKGROUND: This study was performed to clarify the treatment outcome of patients with primary mediastinal germ cell tumors (PMGCTs), focusing on the clinical manifestations and management during definitive therapy and long‐term follow‐up. METHODS: In this study, we retrospectively reviewed the medical records of patients with PMGCTs treated at Shinshu University School of Medicine, and examined the clinical profiles and treatment outcomes of 22 patients (mean age of 29 years) with primary mediastinal GCTs treated at our hospital between 1983 and 2019. RESULTS: Five patients were diagnosed with pure seminoma and 17 had nonseminomatous GCT. A total of 21 patients were treated with cisplatin‐based chemotherapy and 15 patients (68.2%) underwent thoracic surgery after chemotherapy. Although all cases of nonseminomatous GCT were negative for tumor markers after cisplatin‐based chemotherapy, two cases showed variable GCT cells and two had somatic components (angiosarcoma and rhabdomyosarcoma) in resected specimens. Three relapsed soon after surgery. Growing teratoma syndrome developed during chemotherapy in four cases. Urgent thoracic surgery was performed in three patients, but one case was inoperable. The calculated 10‐year overall survival rates were 100% in mediastinal seminoma and 64.7% in NSGCT. During follow‐up, second non‐GCT malignancies developed in three patients (colon cancer, 190 months; thyroid cancer, 260 months; non‐small cell lung cancer, 250 months after the initial chemotherapy) and one patient with primary mediastinal seminoma was associated with multiple type I endocrine tumors. CONCLUSIONS: Our experiences demonstrated that long‐term survival and/or cure can be achieved with adequate chemotherapy followed by local surgical treatment even in patients with mediastinal GCTs. However, the clinical manifestations and biological behaviors during and/or after chemotherapy were complex and varied. In addition, the development of secondary malignancies should be taken into consideration for long‐term follow‐up. Clinicians should be aware of the various clinical features and secondary malignancies in primary mediastinal GCTs.