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

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.

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).

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%.

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.