Characteristics and Treatment of Primary Mediastinal Seminomas: A Single-center Report of 27 Cases

Abstract Background: The low incidence of primary mediastinal seminomas has precluded the development of clinical trials on mediastinal seminomas. We evaluated the characteristics, treatments, and prognosis of patients with primary mediastinal seminoma. Methods: We retrospectively collected data on the clinicopathologic characteristics, treatments, toxicities, and survival of 27 patients from a single center between 2000 and 2018. Mediastinal lymph node staging for lung cancer and Masaoka staging for thymic neoplasms were used for disease characterization. Survival was assessed using the Kaplan-Meier method. Univariate analysis was performed using the log-rank test. Results: The median age was 28 (13-63) years. The most common symptoms were chest pain (29.6%), cough (25.9%), and dyspnea (22.2%). Twenty-four patients showed tumor invasion into adjacent structures. Seven and two patients were diagnosed as having lymph node metastasis and distant metastasis, respectively, whereas 48.1% of patients were diagnosed as having Masaoka stage IIIb disease. Sixteen patients (59.3%) had undergone radiotherapy, whereas 25 (92.6%) had undergone chemotherapy. The most widely used chemotherapy regimens were bleomycin, etoposide, and cisplatin. The median follow-up period was 32.23 (2.7-198.2) months. At 5 and 10 years, the rates of local regional relapse-free survival were 90.9% and 90.9%; overall survival, 100.0% and 80.0%; progression-free survival, 86.4% and 86.4%; distant metastasis-free survival, 95.2% and 95.2%; and cancer-specific survival, 100.0% and 100.0%, respectively. Conclusions: Primary mediastinal seminoma was frequently diagnosed in patients with tumor invasion into adjacent structures. Chemotherapy was the most widely used treatment. The disease was sensitive to chemoradiotherapy, and the prognosis was favorable.