Ewing sarcoma

The term Ewing’s sarcoma family of tumors (ESFT) describes a group of highly malignant small-blue-round cell tumors, which are characterized by recurrent balanced translocations usually involving the EWSR1 gene on chromosome 22. Ewing sarcomas account for approximately 16% of all bone sarcomas and mostly affect children and adolescents. 80% of all patients are younger than 20 years. One quarter of all tumors is localized in the pelvis and another 20% in the femur. About 25% of all patients have distant metastases at diagnosis, which are usually localized in the lungs, other bones and the bone marrow. However, even patients without detectable metastases have micrometastases at diagnosis, so that all patients require a systemic chemotherapy, additionally to local treatment. This combined treatment leads to survival rates of 60-70% of patients with a clinically localized disease at diagnosis. Ewing sarcomas are sensitive to local radiotherapy, which was the treatment of choice in the past. However, surgical excision of the entire tumor surrounded by a layer of healthy tissue is thought to be associated with a survival benefit of 10-15%, which is why surgical treatment – often combined with pre- or postoperative radiotherapy – is considered to be the treatment of choice. In specialized centers adequate surgical excision can be achieved in the vast majority of patients by limb-salvage surgery, without compromising the function of the affected extremity. It should be noted, that tumor-debulking procedures followed by postoperative radiotherapy offer no benefit compared to radiotherapy alone, and are only acceptable in patients with spine tumors and acute neurological complications. Following the excision of most Ewing sarcomas in the extremities and pelvis, it is necessary to reconstruct the resulting defect. The most common form of reconstruction is endoprosthetic replacement, which involves implanting specialized metallic megaprostheses. The choice of the optimal implant and the of the optimal reconstruction method depends on several factors, such as tumor site and extension, as well as patient age, activity level and expected prognosis. For that reason the treating surgeon should be proficient in several different reconstruction options. Given the complexity of the treatment of these tumors, an extensive experience in the interdisciplinary treatment of Ewing sarcoma is required to administer the best possible treatment to each patient.