What is Ewing sarcoma?
Ewing sarcoma is a rare form of bone cancer, making up only 1% of pediatric cancers and developing in only a few hundred patients per year in the United States. While primarily a bone tumor, it can infrequently arise in soft-tissue as well. It is most common in children and young adults, but it can occur in adults as well. It frequently begins in long bones such as the femur, tibia or humerus or in the pelvis but can also develop in flat bones such as the ribs and clavicle.
What causes it?
Several specific genetic mutations have been linked to Ewing sarcoma. These mutations all affect a gene called EWSR1, which in turns leads to tumor growth and the development of symptoms. While these tumors occur more frequently during active growth periods such as during a child’s adolescent years, it is unclear why this specific mutation develops. There is no evidence that environmental, social, dietary or other external factors contribute to its development. It is more common in patients of European decent and less common in patients of African descent.
What are the symptoms?
Symptoms include a painful swollen area. When in an extremity, this may be more visible. If located in the pelvis or spine, it may be harder to visualize, and pain may be the main symptom. Patients may report varying degrees of discomfort even while sitting or at rest. They may experience pain that wakes them from sleep. Pain may prevent normal range of motion and patients may report stiffness, weakness, or other subjective senses of discomfort.
How is it diagnosed?
Ewing sarcoma is diagnosed using imaging studies, such as plain x-rays and MRI. A CT scan of the chest and either a PET scan or a bone scan is often obtained as well to detect the extent of the disease. Ultimately, a biopsy is required to sample the tumor and review its microscopic appearance. A bone marrow biopsy is often performed as well.
How is Ewing sarcoma treated?
• Ewing sarcoma requires a comprehensive team approach, including the multi-disciplinary expertise of orthopaedic oncologists, pediatric oncologists, medical oncologists, radiation oncologists, musculoskeletal radiologists, bone and soft-tissue pathologists, nuclear medicine specialists, surgical oncologists, plastic and reconstructive surgeons among others.
• Treatment includes both systemic chemotherapy and “local control,” which might include surgery, radiation therapy, or both. After a few months of treatment with chemotherapy, the tumor is either surgically removed or radiated. Thereafter, additional chemotherapy is administered. Treatment generally spans 9-10 months.
• Following the completion of treatment, patient will require close surveillance for a period of 5 years. This includes physical examinations and periodic imaging studies. Many patients continue to follow up even after 5 years, albeit at a reduced frequency.