Nonparameningeal head and neck rhabdomyosarcoma in children and adolescents: Lessons from the consecutive International Society of Pediatric Oncology Malignant Mesenchymal Tumor studies

Background: This article reports risk factors and long-term outcome in localized nonparameningeal head and neck rhabdomyosarcomas in children and adolescents from a combined dataset from 3 consecutive international trials. Methods: Data from 140 children (9.3% of total) prospectively enrolled in the International Society of Pediatric Oncology Malignant Mesenchymal Tumor (SIOP-MMT)-84/89/95 studies were analyzed. Results: Primary site was: superficial face in 46%; oral cavity (21%); neck (19%); and salivary glands (14%). Local control was achieved in 96%, but 49% relapsed (locoregionally 91%). At median follow-up of 10 years, 5-year overall survival (OS) was 74.7% (67.4% to 81.9%) and event-free survival 48.9% (40.6% to 57.2%), although this improved with successive studies. Radiotherapy (RT) as first-line treatment was independently prognostic for event-free survival (relative risk [RR] = 0.4 [range, 0.2–0.7]; p <.01) even if it did not impact OS (RR = 1 [range, 0.5–2]). Conclusion: High rates of locoregional relapse were seen in head and neck rhabdomyosarcoma that should be prevented by more frequent use of RT in this primary.