Diagnosis and treatment of rhabdomyosarcomas

Abstract

Rhabdomyosarcoma (RMS) is a soft tissue sarcoma. The primary tumor is most commonly localized in the head and neck, the urogenital system, or the limbs. Classification by the World Health Organization has distinguished four histopathological RMS subtypes: embryonal, alveolar, pleomorphic, and spindle cell/sclerosing. Differential diagnosis of RMS includes melanoma, malignant neoplasm of peripheral nerve sheaths, liposarcoma, and PEComa. Among typical cytogenetic changes in RMS are chromosomal translocations t(2;13)(q35;q14) and t(1;13) (p36;q14). They lead to the formation of fusion genes that have a prognostic value. In the course of RMS, changes may also be present in signaling pathways, including RAS-PI3K, Wnt/b-catenin, receptor tyrosine kinase pathways, and myogenesis regulation. In 30% of patients at the time of diagnosis of RMS, distant metastases are present, most commonly to lungs, lymph nodes, bones, and bone marrow. Treatment of patients with RMS requires a multidisciplinary approach, and steadily perfected diagnostic techniques contribute to the individualization of therapeutic strategies. Optimal treatment of localized RMS is based on surgery combined with radiotherapy and chemotherapy. If distant metastases are present, the basic therapeutic method is multidrug chemotherapy, most frequently based on vincristine, dactinomycin, ifosfamide/cyclophosphamide, and etoposide. Despite intensive treatment, the 5-year survival index for RMS is not greater than 50%. There are still no unequivocal guidelines concerning the treatment in patients with local or distant recurrences.