Ewing sarcoma (ES) is a rare malignancy that most often presents as an undifferentiated primary bone tumor; less commonly, it arises in soft tissue (extraosseous Ewing sarcoma, EES). Both are part of a spectrum of neoplastic diseases known as the Ewing sarcoma family of tumors (EFT), which also includes the more differentiated peripheral primitive neuroectodermal tumor (PNET, previously called peripheral neuroepithelioma, adult neuroblastoma, and Askin's tumor of the chest wall) . PNET can also present either in bone or soft tissue. Because these tumors share similar histological and immunohistochemical characteristics and unique nonrandom chromosomal translocations, they are considered to have a common origin [2-5]. (See "Diseases of the chest wall", section on 'Malignant neoplasms'.)
In addition to their immunohistochemical and cytogenetic similarities, the EFT share important clinical features. These include a peak incidence between the age of 10 and 20 (70 percent of affected patients are under the age of 20), a tendency towards rapid spread to lungs, bone, and bone marrow, and responsiveness to the same treatments that include chemotherapy and radiotherapy. As with osteosarcoma (the other major sarcoma affecting bone), advances in multidisciplinary management over the past 30 years have resulted in a marked improvement in long-term survival. In data derived from the Surveillance, Epidemiology and End Results (SEER) program of the National Cancer Institute, five-year survival rates for patients with Ewing sarcoma rose from 36 to 56 percent during the periods 1975 to 1984 and 1985 to 1994 . (See "Bone sarcomas: Preoperative evaluation, histologic classification, and principles of surgical management".)
Here we will discuss the management of the EFT. The epidemiology, pathology, molecular genetics, clinical presentation, and diagnosis of these tumors, surgical principles, indications for limb sparing surgery, indications for radiation therapy (RT), and treatment of central (supratentorial) PNET tumors are discussed elsewhere. (See appropriate topic reviews).
GENERAL TREATMENT PRINCIPLES
Despite the fact that fewer than 25 percent of patients have overt metastases at the time of diagnosis, EFT is a systemic disease. Because of the high relapse rate (80 to 90 percent) in patients undergoing local therapy alone, it is surmised that the majority of patients have subclinical metastatic disease at the time of diagnosis, even in the absence of overt metastases.
Chemotherapy can successfully eradicate these deposits, and modern treatment plans all include chemotherapy, usually administered prior to and following local treatment. For patients with localized disease, the addition of several months of intensive multiagent chemotherapy to local therapy has had a dramatic impact on survival, and reported five- and 10-year survival rates are now approximately 70 and 50 percent, respectively [7-16].