Management of Residual Disease After Therapy for Mediastinal Germ Cell Tumor and Normal Serum Markers

Abstract

Five to 10% of germ cell tumors originate in the anterior mediastinum. Fewer than 10–20% of anterior mediastinal masses are found to be primary mediastinal germ cell tumors, the majority consisting of thymic or thyroid pathologies or lymphomas. Germ cell tumors have three histologic categories: pure teratoma or pure seminoma with no other germ cell elements and nonseminomatous germ cell tumors. Sixty to 70% of all mediastinal germ cell tumors are teratomas, which are typically mature but occasionally demonstrate immature elements. Mature teratomas are almost always cured with surgical resection alone. Immature teratomas can grow more rapidly and also can degenerate into non-germ cell histologies, such as sarcomas and epithelial cancers, that are resistant to chemotherapy. Mediastinal seminomas have a high rate of cure with cisplatin-based chemotherapy alone. Unlike primary mediastinal nonseminomatous germ cell tumors (PMNSGCT), mediastinal seminomas have a prognosis similar to seminomas that originate in the testes or retroperitoneum.1 The vast majority of residual masses following chemotherapy for mediastinal seminoma represent complete tumor necrosis without viable neoplasm. Seminomas are therefore classified as favorable prognosis germ cell tumors.