Nonorbital, Nonparameningeal Head and Neck Rhabdomyosarcoma: A Report From the Children's Oncology Group.

Abstract

Background: Rhabdomyosarcoma (RMS) is the most common pediatric head and neck soft-tissue sarcoma. Intergroup Rhabdomyosarcoma Study I-IV demonstrated that patients with alveolar RMS (ARMS), Group III disease, or clinically involved regional lymph nodes had a worse prognosis. The outcomes and prognostic features of patients with nonorbital, nonparameningeal head and neck (NONPHN) RMS treated in subsequent Children's Oncology Group (COG) trials have not been reported.

Procedure: Patients enrolled in COG low-risk (D9602 or ARST0331), intermediate-risk (D9803 or ARST0531), and high-risk (D9802, ARST0431, or ARST08P1) trials were included. All patients received chemotherapy. Those with Group I (completely resected) ARMS and those with Group II (microscopic residual) or Group III (macroscopic residual) RMS received 36-50.4 Gy adjuvant radiotherapy (RT).

Results: One hundred seventy-two patients with NONPHN RMS were treated across the seven trials. Most patients had cheek primaries (30%), Group II (38%) or Group III (34%) disease, no clinical or radiological evidence of nodal involvement (N₀, 80%), and received RT (70%). The median follow-up was 7.7 years. Five-year event-free survival and overall survival were 70.8% and 83.7%, respectively. The regional failure rate for patients with N₀ disease was 2%.

Conclusions: Outcomes for patients with NONPHN RMS were similar to contemporary studies. Despite lower RT target volumes on the ARST-series versus the D-series protocols, patients with Group III tumors maintained comparable outcomes. Low regional failure rates suggested that sentinel lymph node sampling in patients with N₀ disease and elective nodal RT in patients with ARMS and N₀ disease are not necessary.