Emerging chemotherapeutic strategies and the role of treatment stratification in Ewing sarcoma.

The Ewing sarcoma family of tumors (ESFT) is one of the most common groups of malignancies arising in children, adolescents, and young adults up to approximately 25 years of age. It comprises Ewing sarcoma arising from bone and extraosseous Ewing sarcoma arising from soft tissues (which includes peripheral neuroectodermal tumors and Askin tumor arising from the chest wall). Ewing sarcoma is treated successfully in many cases by a combination of chemotherapy, surgery, and radiotherapy. A number of prognostic factors have been identified that can be used to stratify patients according to the risk of relapse, allowing optimization of treatment. These can be categorized as tumor-related factors (presence of metastases, tumor site, volume, lactic dehydrogenase level, chromosomal translocation type, presence of fusion transcripts in blood and bone marrow), treatment-related factors (local therapy, histologic response to chemotherapy, radiologic response to chemotherapy, chemotherapy regimen), and patient-related factors (gender, age). Newer chemotherapeutic agents are currently being investigated, and there is now increasing interest in the identification of molecular targets in ESFT that could be exploited therapeutically, which include the mammalian target of rapamycin (mTOR) and insulin growth factor-1 (IGF-1) receptor pathways.