What is ewing sarcoma

Overview

Ewing sarcoma is a malignant tumor that develops in bone, most commonly in children and young adults aged 10-20 years old. It is the second most common primary bone cancer after osteosarcoma and represents approximately 9% of all primary bone cancers. The disease is characterized by rapid growth and a tendency to spread to other tissues, particularly the lungs.

Causes and Risk Factors

Ewing sarcoma is caused by a specific chromosomal abnormality where genetic material from chromosome 22 fuses with material from chromosome 11, creating an abnormal EWSR1-FLI1 fusion gene. This fusion produces an abnormal protein that causes bone cells to become cancerous. The exact reason why this translocation occurs is not fully understood, and there are no established preventable risk factors. The disease appears to arise randomly and is not hereditary in most cases.

Symptoms and Diagnosis

Common symptoms include localized bone pain and swelling in the affected area, sometimes accompanied by fever. Patients may develop a palpable mass or experience limited mobility. Diagnosis typically involves X-ray imaging followed by MRI for detailed evaluation, and confirmation through biopsy. CT scans are often used to detect metastatic disease in the lungs and other organs.

Treatment Approach

Modern treatment uses a multimodal approach combining neoadjuvant chemotherapy (before surgery), surgical resection of the tumor, and sometimes radiation therapy. Standard chemotherapy regimens include doxorubicin, cyclophosphamide, etoposide, ifosfamide, and cisplatin. Surgery aims to completely remove the tumor while preserving limb function when possible. Radiation is typically reserved for cases where surgical margins cannot be achieved or for metastatic disease.

Prognosis and Survival

Patients with localized Ewing sarcoma treated with multimodal therapy achieve 5-year overall survival rates of 65-75%. Outcomes are significantly worse for patients presenting with metastatic disease, with 5-year survival rates around 20-30%. Prognostic factors include tumor size, location, and response to chemotherapy.