Primary mediastinal nonseminomatous germ cell tumors: results of modern therapy including cisplatin-based chemotherapy.

PURPOSE: Primary mediastinal nonseminomatous germ cell tumors (NSGCT) are uncommon neoplasms and clinically and biologically distinct from other germ cell tumors (GCT). We describe the clinical and biologic features of these patients and evaluate the results of treatment during the cisplatin era.

PATIENTS AND METHODS: Between 1976 and 1993, 38 patients with mediastinal NSGCT received cisplatin-based chemotherapy as part of their primary treatment. Twenty-nine of them were initially treated at the Institut Gustave-Roussy (IGR), VillejuiF, France, and nine were referred for salvage treatment.

RESULTS: Of the 29 patients initially treated at IGR, 11 (39%) had metastasis. A complete response (CR) to therapy was obtained in 19 of 29 patients (66%) after chemotherapy and surgery. Ten patients (34.5%) have remained free of disease with a median follow-up of 89 months. All patients who did not achieve a CR died of disease. The 2-year overall survival rate for the IGR patients is 45% and the 2-year disease-free survival is 37%. Only the presence of extrapulmonary metastasis was of prognostic significance in the univariate analysis (P = .0095). None of the 20 patients who required salvage therapy is currently disease-free. Five patients developed and subsequently died of a hematologic malignancy at an interval range of 1 to 47 months from treatment of mediastinal NSGCT. Cytogenetic analysis of leukemic cells found an isochromosome of the short arm of chromosome 12 (12p) in two cases. The incidence of leukemia was 21% in patients who attained a CR.

CONCLUSION: Primary mediastinal NSGCT is a clinical and biologic entity that should be distinguished from other GCT. About 40% of these patients can envisage long-term survival with modern therapy that includes cisplatin-based chemotherapy followed by surgical resection of residual masses. New strategies are required for patients who do not attain a CR. Predictive factors and improvement in therapy are required for mediastinal NSGCT-associated leukemia.