PRIMARY CHEMOTHERAPY IN RHABDOMYOSARCOMAS AND OTHER MALIGNANT MESENCHYMAL TUMORS OF THE ORBIT - RESULTS OF THE INTERNATIONAL-SOCIETY-OF-PEDIATRIC-ONCOLOGY MMT-84 STUDY

Purpose: The MMT 84 multicentric prospective trial of the International Society of Pediatric Oncology (SIOP) was designed to (1) test the effectiveness of ifosfamide 3 g/m2 on days 1 and 2, vincristine 1..5 mg/m2 on days 1 and 14, and dactinomycin 0.9 mg/m2 on days 1 and 2 (IVA) repeated every 21 days; and (2) reduce late effects of treatment by reserving radiation therapy to the primary site for patients not achieving a complete response (CR) to primary chemotherapy. Materials and Methods: Between 1984 and 1989, the MMT 84 study registered 34 children with nonmetastatic rhabdomyosarcomas (RMSs) and other malignant mesenchymal tumors (MMTs) of the orbit in this trial. Results: The 4-year event-free survival rate is 62% ± 9% (SD) and the 4-year survival rate 86% ± 7% (SD). A total of 11 local recurrences occurred, 10 among 22 patients treated without initial radiation. Salvage of local failure was achieved in nine of 11 patients with the use of radiation and additional chemotherapy, but three later developed distant metastases and two have died. One isolated regional lymph node failure has occurred, while no patient relapsed with isolated distant metastases. Six of 12 patients who failed are alive with no evidence of disease from 16 to 50 months after relapse. The treatment was well tolerated in all patients, except for one with renal tubular acidosis and one who died of cardiotoxicity. Twelve patients remain in first remission without the use of radiation to the primary tumor from 27 to 84 months. Conclusion: Despite a higher incidence of local recurrence when treated by primary chemotherapy, early survival rates were not compromised and a significant number of patients avoided the late effects of radiation. However, longer follow-up is required to assess the ultimate outcome of patients treated in this manner.