Soft Tissue Sarcoma or Malignant Mesenchymal Tumors in the First Year of Life: Experience of the International Society of Pediatric Oncology (SIOP) Malignant Mesenchymal Tumor Committee

Abstract

Purpose To describe the outcome of infants with a histologically confirmed diagnosis of malignant mesenchymal tumor (MMT) included in the International Society of Paediatric Oncology studies MMT 84 and MMT 89. Patients and Methods One hundred two infants (≤ 12 months old) were included. Twenty-four children were less than 3 months old, and 16 were less than 1 month old. Sixty-four patients had rhabdomyosarcoma (RMS), 26 had undifferentiated sarcoma, and 12 had other histology. Clinical TNM stage was stage I (41%), II (39%), III (6%), and IV (14%). First-line treatment was ifosfamide, vincristine, dactinomycin, whereas the second-line combination consisted of either cisplatin and doxorubicin (in MMT 84) or vincristine, carboplatin, etoposide/teniposide (in MMT 89). Chemotherapy doses were adapted to age. Local therapy was conservative surgery as often as possible. Results After a median follow-up of 7.8 years (range, 0.1 to 13 years), 5-year overall survival (OS) and event-free survival rates were 66% and 55% for the total study population and 72% and 60% for nonmetastatic patients, respectively. Only two of 13 stage IV patients survived. Sixty-seven percent of newborn infants survived. Infants with alveolar subtype had a poorer survival than those with non-RMS MMT or nonalveolar RMS (5-year OS, 37% v 75% or 82%, respectively; P = .002). When compared with older children with MMT, young age does not seem to be an important prognostic factor. Conclusion OS was satisfactory even when local treatment was not aggressive, although the prognosis was poor for infants with alveolar RMS or metastatic tumors. Chemotherapy toxicity was manageable with appropriate dose modification.