Alveolar Soft Part Sarcoma in Pediatric and Young Adult Patients: A Report From the Children's Oncology Group Study...

Alveolar soft part sarcoma (ASPS) is a rare soft tissue sarcoma occurring most commonly in adolescence and young adulthood.

We present the clinical characteristics, treatments, and outcomes of patients with newly diagnosed ASPS enrolled on the Children's Oncology Group study ARST0332. Patients were treated with risk-adapted therapy, including surgery with or without radiotherapy and ifosfamide and doxorubicin.

Twenty-four patients with ASPS enrolled on ARST0332 between 2007 and 2012 were analyzed. The majority of primaries were extremity tumors (71%) and > 5 cm (54%). Nearly half (46%) of patients had metastatic disease at diagnosis, all of whom had primary tumors > 5 cm and pulmonary metastases with or without extrapulmonary metastases. Six patients were evaluable for response to neoadjuvant chemoradiotherapy without an objective response. Estimated 5-year event-free survival (EFS) and overall survival (OS) were 91% and 100% for low-risk (n = 11), 0% and 50% for intermediate-risk (n = 2), and 0% and 59% for high-risk disease (n = 11), respectively. EFS and OS differed significantly by maximal tumor diameter, presence or absence of metastatic disease, risk group, treatment arm, and upfront primary site resection status.

Patients with low-risk ASPS (non-metastatic, grossly resected tumors ≤ 5 cm) had excellent outcomes with surgery with or without radiation on ARST0332. Chemotherapy has been reported to be generally ineffective in ASPS and, indeed, there were no objective responses to neoadjuvant chemoradiotherapy on ARST0332. All patients treated with combination chemoradiotherapy ultimately developed disease progression/relapse. A different therapeutic approach is needed for patients with unresectable or metastatic ASPS.