Multimodality treatment outcome in patients with primary malignant mediastinal germ cell tumor in adults

Background Malignant mediastinal germ cell tumor (MGCT) is rare and has poor outcomes even after multimodality treatment. Data from resource-poor countries are scarce in the literature. Aims To evaluate the clinicopathologic features and treatment outcome of primary malignant MGCT at our center. Methods and Results Single institutional data review of patients aged >= 18 years, treated with a diagnosis of malignant MGCT between Nov'2013 and Nov'2019. Risk stratification was done as per International Germ Cell Cancer Collaborative Group (IGCCCG) classification. Patients were treated with platinum based chemotherapy and surgical resection for the residual disease was performed in non-seminomatous histology.28 patients had MGCT with a median age of 25 years (range:18-36) and all were male. Seven patients had superior vena cava obstruction (SVCO) at diagnosis and pre-treatment histological diagnosis was available in 23 (82%) patients. Seven (25%) patients had seminoma histology, all were of good risk as per IGCCCG risk criteria, whereas others had non-seminoma histology with poor-risk group. Seven patients with seminoma histology achieved a complete response after initial treatment. Six patients with non-seminoma histology underwent complete resection of residual disease post-chemotherapy and five revealed residual viable tumors. After a median follow-up of 10.8 months (range:2.9-75), 3-year progression-free survival (PFS) and overall survival (OS) estimate was 61.2% and 94.7% in the whole cohort, respectively and 3-year PFS and OS estimate was 100% in patients with seminoma histology. Conclusions This is the largest data set of MGCT patients' outcomes reported from India with multi-modality treatment. All patients were male and one-fourth had SVCO at presentation. Seminoma histology patients had a 100% outcome after initial platinum based chemotherapy. But, those with non-seminoma histology had a poor outcome even with chemotherapy and surgery.