Malignant retroperitoneal and abdominal germ cell tumors: An intergroup study

Background/Purpose: This randomized study examined survival (S) and event-free survival (EFS) rates using high-or standard-dose cisplatin-based combination chemotherapy and surgical resection for this subset of germ cell tumors. Methods: Twenty-six of 317 patients enrolled on the POG 9049/COG 8882 intergroup study for malignant germ cell tumors had abdomen or retroperitoneum as the primary site. Twenty-five of 26 were eligible for inclusion (n = 25). Patients had biopsy or resection at diagnosis and randomization to chemotherapy including etoposide, bleomycin, and either standard-dose (PEB) or high-dose cisplatin (HDPEB). In patients with initial biopsy, delayed resection was planned. Results: Median age was 26 months. There were 14 girls and 11 boys. There were 3 stage I to II, 5 stage III, and 17 stage IV patients. Surgical management included primary resection in 5, resection after chemotherapy in 13, and biopsy or partial resection in 7 patients. Overall 6-year EFS rate was 82.8% ± 10.9%, and 6-year survival rate was 87.6% ± 9.3%. By group, 6-year survival rate was 90.0% ± 11.6% for PEB and 85.7 ± 14.5% for HDPEB. Deaths include one from sepsis, one from malignant tumor progression, and one from bulky disease caused by benign components despite response of the malignant elements to chemotherapy. Conclusions: Malignant germ cell tumors arising in the abdomen and retroperitoneum have an excellent prognosis despite advanced stage in most children. Aggressive resection need not be undertaken at diagnosis, but a concerted attempt at complete surgical removal after chemotherapy is important to distinguish viable tumor from necrotic tumor or benign elements that will not benefit from further chemotherapy.