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Soft tissue sarcomas arising in the retroperitoneal space in children. A report from the Intergroup Rhabdomyosarcoma
Insights
Pediatric retroperitoneal soft-tissue sarcomas present with pain or abdominal masses and have a poor prognosis. Treatment challenges and high relapse rates underscore the need for improved therapeutic strategies in children.
Area of Science:
- Pediatric Oncology
- Surgical Oncology
- Medical Oncology
Background:
- Soft-tissue sarcomas in the retroperitoneal space are rare pediatric malignancies.
- These tumors often present late with significant size and local extension.
- The Intergroup Rhabdomyosarcoma Study (IRS) provides a framework for evaluating treatment outcomes.
Purpose of the Study:
- To analyze the clinical characteristics, treatment, and outcomes of children with retroperitoneal soft-tissue sarcomas.
- To identify prognostic factors influencing survival and relapse in this patient cohort.
- To evaluate the challenges associated with treatment delivery in this anatomical location.
Main Methods:
- Retrospective analysis of 101 children registered on IRS studies I and II with retroperitoneal soft-tissue sarcomas.
- Data collection included presenting symptoms, tumor histology, size, stage, treatment modalities (surgery, radiation, chemotherapy), and follow-up.
- Treatment response, relapse rates, and survival were assessed based on protocol-defined criteria.
Main Results:
- Median age at diagnosis was 6.5 years; median tumor size was 10 cm, larger than average IRS studies.
- Embryonal/botryoid rhabdomyosarcoma was the most common histology (58%).
- Complete remission (CR) was achieved in 58% of evaluable patients, but 59% of those in CR relapsed. Median disease-free and overall survival were 54 and 88 weeks, respectively. Significant treatment toxicities included myelosuppression and cystitis.
Conclusions:
- Children with retroperitoneal soft-tissue sarcomas face a poor prognosis due to large tumor size and unresectability.
- High rates of relapse and treatment-related toxicities highlight the need for novel therapeutic approaches.
- Multidisciplinary management is crucial for optimizing outcomes in these challenging pediatric cancers.
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 less than 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.