Rhabdomyosarcoma: an overview.

Rhabdomyosarcoma (RMS) is a malignant tumor of mesenchymal origin thought to arise from cells committed to a skeletal muscle lineage. With approximately 250 cases diagnosed yearly in the United States, it is the third most common extracranial solid tumor of childhood after Wilms' tumor and neuroblastoma. Important epidemiologic, biologic, and therapeutic differences have been elucidated within the RMS family. Common sites of primary disease include the head and neck region, genitourinary tract, and extremities. A site-based tumor-nodes-metastasis staging system is being incorporated into use for assessing prognosis and assigning therapy in conjunction with the traditional surgicopathologic clinical grouping system. The development of intensive multimodality treatment protocols tested in large-scale international trials has resulted in significant improvements in outcome, especially for patients with local or locally extensive disease for whom a 60%-70% disease-free survival can be expected. Despite aggressive approaches incorporating surgery, dose-intensive combination chemotherapy, and radiation therapy, the outcome for patients with metastatic disease remains poor. Future challenges include the development of less toxic therapy for patients with localized disease and new approaches for patients with metastatic disease.