Adjuvant chemotherapy with CAV/IE for malignant transformation of teratoma to primitive neuroectodermal tumor (PNET): An institutional analysis from Indiana University.

Abstract

5026 Background: Malignant transformation of teratoma to PNET has an aggressive disease biology and generally poor outcomes when metastasis occurs. The optimal management of patients (pts) with PNET who have complete surgical extirpation is unknown. Most pts who are monitored with surveillance will relapse. We report results from pts with metastatic PNET who had complete surgical resection to NED status followed by adjuvant chemotherapy, most commonly cyclophosphamide + doxorubicin + vincristine alternating with ifosfamide + etoposide (CAV/IE) for 4 cycles. Methods: We reviewed records for pts with histologically confirmed malignant transformation of teratoma at Indiana University from 1990 to 2020. We identified 13 pts with PNET who underwent resection of metastatic disease to NED status followed by treatment with adjuvant chemotherapy, most commonly CAV/IE comprising of cyclophosphamide (1200 mg/m2), doxorubicin (75 mg/m2), and vincristine (2 mg/m2) alternating with ifosfamide (1.8 g/m2) plus etoposide (100 mg/m2). Treatment was delivered every 3 weeks for 4 cycles or until unacceptable toxicity. Results: Thirteen pts with metastatic PNET resected to NED status and received adjuvant chemotherapy were identified. Median age at diagnosis was 29 (range, 20 to 55). Primary tumor site was testis in 11 pts, retroperitoneum in 1 pt, and mediastinum in 1 pt. Metastasis site was retroperitoneal lymph nodes in 11 pts, mediastinal lymph nodes in 1 pt, and local mediastinal recurrence in 1 pt. After resection to NED status, all 13 pts were treated with adjuvant chemotherapy: 11 pts were treated with CAV/IE and 2 received etoposide-ifosfamide-cisplatin (VIP) x 2. Among the 11 pts who received CAV/IE: 3 pts received < 4 cycles due to toxicity and 8 completed 4 cycles. With a median follow-up of 16.3 months, 3 of 13 pts relapsed (23%) and 10 of 13 remained continuously disease free (77%). Of those who relapsed, median time to relapse was 9.3 months, 2 remained alive with disease at follow up and one patient died of disease progression. Conclusions: Adjuvant CAV/IE improves the outcomes of pts with malignant transformation of teratoma to PNET and who had resection of metastasis to NED status. Most pts who received adjuvant therapy remain continuously disease-free in comparison to historically high relapse rates in pts with resected PNET monitored with surveillance.