Soft tissue sarcomas arising in the retroperitoneal space in children a report from the intergroup rhabdomyosarcoma study (IRS) committee

Abstract
One hundred one eligible children with soft-tissue sarcomas arising within the retroperitoneal space have been registered on Intergroup Rhabdomyosarcoma Study Committee (IRS) studies I and II and followed for at least 2 years or until death. The most common presenting symptoms and signs were pain in the abdomen or lower extremities, and/or an abdominal mass, usually noted by a parent or a physician seeing the child for other complaints. The median age at diagnosis was 6.5 years and the sex ratio (M/F) 1.7:1. Histologic types were embryonal or botryoid rhabdomyosarcoma (RMS) in 58 patients, alveolar RMS in 8, pleomorphic RMS in 2, undifferentiated sarcoma in 20, extraosseous Ewing's sarcoma in 4 and unspecified sarcoma in 9. Median tumor size was 10 cm, significantly larger than the 7.5 cm noted in the IRS studies as a whole (P < 0.05). One patient had complete tumor removal (Group I); 12 had grossly complete removal with microscopic residual tumor (Group II). Fifty-one patients had residual local tumor after biopsy or partial resection (Group III) and 37 patients had distant metastases at diagnosis (Group IV). Treatment included surgery, radiation therapy (RT) and combination chemotherapy with vincristine and actinomycin D with or without cyclophosphamide and Adriamycin (doxorubicin) according to protocol. Thirty-nine of 99 patients (39%) had major difficulties in the delivery of specified RT. Seventy patients received sufficient therapy to be evaluable for treatment response. Forty-one (58%) achieved a complete remission and 16 (23%) achieved partial remission. Twenty-four of 41 children (59%) achieving a CR have relapsed. The proportion of children who remained relapse-free at 2 and 3 years of follow-up was 44% or 42%, respectively. Overall, 40 children have developed recurrent sarcoma and the median disease-free interval and overall survival times were 54 and 88 weeks, respectively. Most children experienced severe myelosuppression; there were three early deaths from infection which occurred during granulocytopenic periods. One third of the patients experienced cystitis. Children with soft-tissue sarcomas arising in the retroperitoneal space have a poor prognosis associated with large tumors which, because of location and/or extent (Groups III or IV), are unresectable and difficult to treat. Cancer 56: 2125-2132, 1985.