Metastatic malignant transformation of teratoma to primitive neuroectodermal tumor (PNET): Results with PNET-based chemotherapy.

Abstract

4598 Background: Metastatic germ cell cancers are highly chemosensitive and have 80% cure rate with cisplatin based chemotherapy. Post-chemotherapy teratoma can usually be surgically resected. However, teratoma, which is pleuripotent tissue, can undergo malignant transformation along mesodermal elements to PNET. Unlike teratoma, PNET can metastasize and render a patient unresectable and incurable. We report the results of treatment of patients with PNET with cyclophosphamide + doxorubicin + vincristine (CAV) alternating with ifosfamide + etoposide (IE). Methods: We reviewed 81 patients with histologically confirmed PNET transformed from testicular teratoma at Indiana University from 1998 to 2011. We identified 13 cases who were treated with chemotherapy comprising cyclophosphamide 1000-1200 mg/m2, doxorubicin 50-75 mg/m2, and vincristine 2 mg alternating with ifosfamide 1.8 grams/m2 plus etoposide 100 mg/m2 for 5 days. Treatment was given every 3 weeks with a maximum of 6 cycles or until progression or undue toxicity. Hematopoeitic growth factors were usually incorporated. The remaining 68 patients underwent surgical resection. Results: Ten patients had unresectable disease and 3 were treated in an adjuvant setting. Median age was 31 years (range 20-53). Ten of 13 patients had received prior platinum based chemotherapy. Eight of 10 evaluable patients achieved objective response. Five of those were rendered with no evidence of disease(NED) with further surgery. Although 4 of the 5 patients subsequently relapsed, 1 patient remains alive with NED at 69 months. The 3 patients who received adjuvant treatment after retroperitoneal lymph node dissection (RPLND) are alive with NED at 1, 4 and 8 years. Conclusions: CAV and IE alternating chemotherapy has high objective response rate for PNET transformed from teratoma and results in occasional long term disease free survival when combined with subsequent resection. We recommend adjuvant CAV alternating with IE chemotherapy for patients with PNET after RPLND due to the high probability of recurrent disease and their high chemosensitivity to this regimen.