Primary mediastinal and retroperitoneal malignant germ cell tumors in children and adolescents: Results of the TGM95 trial, a study of the French Society of Pediatric Oncology (Société Française des Cancers de l'Enfant).

Purpose: To examine the clinical presentation, treatment and results in children and adolescents with primary mediastinal (PM) and retroperitoneal (RP) germ cell tumors (GCTs).

Methods: The TGM95 trial for malignant GCTs was conducted in France between 1995 and 2005 to evaluate a strategy adapted to prognostic factors with cisplatin-based chemotherapy and surgical management. We reviewed patients with TGCTs at PM and RP sites.

Results: Among 239 patients, there were 16 patients with PM and 5 with RP tumors, which represent 9% of all patients, highlighting the rarity of these extragonadal locations. A bimodal demographic distribution was observed (11/21 patients <5 years old and 7/21 patients >12 years old). A majority of patients presented with bulky tumors that required urgent care with neoadjuvant chemotherapy. In all patients, elevation of alpha-fetoprotein indicated a yolk sac tumor component. Human chorionic gonadotrophin was elevated in five patients (four adolescents), suggesting a choriocarcinoma or seminoma component. The diagnosis was based on elevation of these tumor markers in addition to imaging. Chemosensitivity was observed for a majority of patients. An aggressive surgical approach allowed a microscopic complete resection in 12/15 patients with PM tumors and 4/5 with RP tumors. Overall, 14/16 and 4/5 patients survived, respectively. Three adolescents died of tumor progression.

Conclusion: In children with mediastinal or RP GCTs, the prognosis is favorable when a strategy of delayed aggressive surgery is performed after cisplatin-based chemotherapy. Younger patients have a better prognosis. Relapses were observed only in adolescents and could not be cured.