Diagnosis and treatment of Ewing's sarcoma.

Ewing's sarcoma is a small round-cell tumor typically arising in the bones, rarely in soft tissues, of children and adolescents. Ewing's sarcoma has retained the most unfavorable prognosis of all primary musculoskeletal tumors. Prior to the use of multi-drug chemotherapy, long-term survival was less than 10%. The development of multi-disciplinary therapy with chemotherapy, irradiation, and surgery has increased current long-term survival rates in most clinical centers to greater than 50%. In addition, the preferred method of tumor resection has changed; limb salvage has nearly replaced amputation of the affected limb. Limb salvage procedures can be performed in place of amputation without compromising patient survival rates. Recent studies have revealed that the pathognomonic translocations involving the EWS gene on chromosome 22 and an ETS-type gene, which is most commonly the Fli1 gene on chromosome 11, are implicated in more than 95% of Ewing's sarcomas, primitive neuroectodermal tumors and Askin's tumors. Therefore, these lesions have become regarded as a single entity, dubbed the Ewing's family of tumors. RT-PCR to detect EWS-ETS gene arrangements is widely used to confirm the diagnosis of Ewing's family of tumors. Experimental results suggest that inhibition of the signaling pathway downstream of the EWS-ETS gene may lead to the development of molecularly targeted therapy in the future.