Ewing tumour: incidence, prognosis and treatment options

Ewing tumours, i.e. Ewing's sarcoma and malignant peripheral neuroectodermal tumours, are the second most common primary malignant tumours of bone in childhood and adolescence, with an annual incidence rate in Caucasians of 3 per 1 million children <15 years of age. Histopathologically small blue round cell tumours, Ewing tumours show a typical chromosomal rearrangement in >95% of cases linking the EWS gene on chromosome 22q12 to a member of the ETS transcription gene family, most commonly to Fli-1 on 11q24. This fusion contributes to the malignant potential of Ewing tumour cells, indeed antisense oligonucleotides may prevent tumour growth in vitro. After open biopsy, and histological and possibly molecular biological confirmation of the diagnosis, treatment consists of several months of multidrug cytostatic therapy and local therapy. Both surgery and radiotherapy may control local disease, but without consequent cytostatic chemotherapy all patients will eventually succumb to distant metastases. With the use of alkylating agents including doxorubicin, cyclophosphamide and/or ifosfamide, and other cytostatic drugs such as actinomycin D (dactinomycin), vincristine and etoposide, long-term survival can be achieved in >50% of patients with localised disease. Patients with clinically detectable metastases at diagnosis, patients not responding to therapy and patients with disease relapse have a significantly poorer prognosis. Maximum supportive care and local therapy managed by an experienced physician are required in all patients, and inclusion of high-risk patients in phase I and II studies is warranted. Hence, treatment of patients with Ewing tumours should be performed in experienced centres only and preferably within controlled clinical trials.