Clinical features and outcomes of young patients with low‐grade non‐rhabdomyosarcoma soft tissue sarcomas treated with a risk‐based strategy: A report from Children's Oncology Group study ARST0332

Abstract

AbstractBackgroundIn retrospective analyses, the Pediatric Oncology Group [POG) and the Federation National des Centres de Lutte Contre le Cancer (FNCLCC) histologic grade predict outcome in pediatric non‐rhabdomyosarcoma soft tissue sarcoma (NRSTS), but prospective data on grading, clinical features, and outcomes of low‐grade NRSTS are limited.MethodsWe analyzed patients less than 30 years of age enrolled on Children's Oncology Group (COG) study ARST0332 (NCT00346164) with POG grade 1 or 2 NRSTS. Low‐risk patients were treated with surgery alone. Intermediate‐/high‐risk patients received ifosfamide/doxorubicin and radiotherapy, with definitive resection either before or after 12 weeks of chemoradiotherapy.ResultsEstimated 5‐year event‐free and overall survival were 90% and 100% low risk (n = 80), 55% and 78% intermediate risk (n = 15), and 25% and 25% high risk (n = 4). In low‐risk patients, only local recurrence was seen in 10%; none with margins greater than 1 mm recurred locally. Sixteen of 17 intermediate‐/high‐risk patients who completed neoadjuvant chemoradiotherapy underwent gross total tumor resection, 80% with negative margins. Intermediate‐/high‐risk group events included one local and seven metastatic recurrences. Had the FNCLCC grading system been used to direct treatment, 29% of low‐risk (surgery alone) patients would have received radiotherapy ± chemotherapy.ConclusionsMost low‐risk patients with completely resected POG low‐grade NRSTS are successfully treated with surgery alone, and surgical margins greater than 1 mm may be sufficient to prevent local recurrence. Patients with intermediate‐ and high‐risk low‐grade NRSTS have outcomes similar to patients with high‐grade histology, and require more effective therapies. Use of the current FNCLCC grading system may result in overtreatment of low‐risk NRSTS curable with surgery alone.