What Is Ewing Sarcoma? Symptoms and Treatment

Ewing sarcoma is a bone cancer generally affecting children and adolescents and is among rare tumors.

Ewing sarcoma can be very aggressive, but its cells tend to respond well to radiation therapy. This cancer is generally diagnosed before metastasis occurs.

An estimated 250 children are diagnosed with Ewing sarcoma each year in the USA.

What Is Ewing Sarcoma?

Ewing sarcoma is a rare cancer generally starting in bone—typically the pelvis (groin region), chest wall or legs—and occurs mainly in children and young people.

James Ewing first described Ewing sarcoma in 1921. He described its cells as looking different from those of osteosarcoma, another bone tumor type.

We also call this cancer type the Ewing family of tumors. These tumors have distinctive cells that generally respond well to radiation treatment.

This rare cancer accounts for only 1.5% of all childhood cancers and is the second most common childhood bone cancer after osteosarcoma.

What Causes Ewing Sarcoma?

Although researchers are unsure why some people develop Ewing sarcoma, mutations in certain genes causing this cancer have been identified in tumor cells.

Genes known to be affected in Ewing sarcoma include those on chromosome 22, the EWSR1 gene, and chromosome 11, the FLI1 gene, with mutationsin these genes.

These genetic mutations arise spontaneously during a person’s lifetime. They are not inherited from a family member; in other words, they are not inherited / germline mutations.

There is no known risk factor making one person more likely than others to develop Ewing sarcoma.

What Are the Symptoms of Ewing Sarcoma?

Ewing sarcoma may cause the following symptoms:

• A bone that breaks easily or without a clear reason
• Fever
• A lump / palpable mass under the skin, generally soft and warm to the touch
• Pain in the affected area, such as the arms, back, chest, legs or pelvis
• Swelling in the affected area

An estimated 87% of Ewing sarcomas are bone sarcomas (sarcoma is the general name for connective tissue tumors). Other types develop in soft tissues such as cartilage surrounding bone.

Ewing sarcoma can metastasize (spread) to other body parts. Its most common metastatic sites are other bones, bone marrow and lungs.

Ewing Sarcoma Is Examined in 3 Main Stages

• Localized Ewing sarcoma: The cancer has not spread to other body parts but may have spread to nearby lymph nodes.
• Metastatic Ewing sarcoma: The cancer has spread to other body parts, such as the lungs, bone marrow or other bones.
• Recurrent Ewing sarcoma: A person has previously had Ewing sarcoma, and the cancer has recurred (returned).

How is Ewing sarcoma diagnosed?

Before diagnosing Ewing sarcoma, the doctor takes a complete medical history and asks about signs and symptoms, when they were noticed and what makes them better or worse. A detailed physical examination is also performed, focusing on the area of concern.

If there is suspicion, an imaging study is recommended to view the affected bone or bones. These tests include:

• Bone X-ray (X-ray scan, plain film)
• Computed tomography (BT)
• Magnetic resonance (MR)

If radiological tests suggest a tumor, the doctor performs a biopsy, taking a sample of bone tissue. A specialist called a pathologist examines this tissue in a laboratory for cancer cells.

The doctor may also request blood tests, a bone marrow biopsy and other scans as needed. These tests can help determine whether the cancer has spread elsewhere.

Treatment of Ewing sarcoma

A medical oncologist, radiation oncologist and orthopedic oncology surgeon work together for this cancer.

Possible treatments for Ewing sarcoma include:

• Chemotherapy: Chemotherapy uses drugs to kill rapidly proliferating cancer cells. It is generally the first treatment for Ewing sarcoma and usually lasts 6-12 months.
• Radiotherapy: Radiation treatment involves killing cancer cells with high-energy X-rays.
• Surgery: In some cases, the tumor must be surgically removed. If a large amount of bone needs removal, replacement with a bone graft or artificial bone may be recommended.
• Stem cells: Stem cell transplantation from a donor’s bone marrow may be used to encourage healthy bone cell growth.

These treatments may be combined depending on how far the cancer has spread and the person’s overall health.

Ewing sarcoma treatment almost always begins with neoadjuvant (tumor-shrinking before the main treatment) multiagent chemotherapy.

Then:

• If the disease is "localized / early stage" and responds well to initial treatment, radiotherapy or surgery is performed, followed by maintenance chemotherapy.
• If the disease is metastatic, local treatments (radiotherapy or surgery) are used, and a change in chemotherapy regimen is also considered (for example, stem cell transplantation with high-dose chemotherapy).