Ewing sarcoma

Ewing sarcoma is a cancer that forms in bone or in the soft tissue around it. It can start in the bones of the legs, arms, feet, hands, chest, pelvis, spine or skull. The pelvis, the thigh bone (femur), the ribs and the bones of the lower leg are common places. When it starts outside a bone, it is called extraosseous Ewing sarcoma. In most people with Ewing sarcoma, about 87 in 100, the cancer starts in a bone.

It is most common in teens and young adults, from the teen years through the mid-20s. It can also happen in younger children and in older adults. Older names for the same tumor include peripheral primitive neuroectodermal tumor (PNET), Askin tumor (Ewing sarcoma of the chest wall) and Ewing sarcoma family of tumors.

Doctors now separate Ewing sarcoma from a few rare look-alike tumors called undifferentiated small round cell sarcomas. These have different gene changes, such as in the CIC or BCOR genes. They are often treated in a similar way, but their outlook is different, so the exact lab diagnosis matters.

Ewing sarcoma is caused by a gene change inside the tumor cells. Two chromosomes swap pieces, and part of a gene called EWSR1 joins part of another gene, most often FLI1. This joined, or fused, gene makes a protein that switches many other genes on and off in the wrong way. The cells then grow out of control. The EWSR1::FLI1 fusion is found in about 85% of Ewing sarcomas.

This gene change happens during a person’s life and is found only in the tumor cells. It is generally not inherited. Often, the reason the change happens is not known. Like other cancers, Ewing sarcoma does not spread from person to person.

In the United States, Ewing sarcoma is about nine times more common in White people than in Black people, with Asian people in between. Part of this difference may come from a common variation in a gene called EGR2. Children with Fanconi anemia may have a higher risk.

The most common signs are pain and swelling near the tumor. There may be a lump that feels soft and warm. Pain can get worse over weeks or months and may wake a child at night. Some people have a limp, fever with no clear cause, tiredness or weight loss. A weakened bone can break with no clear cause.

Diagnosis often takes time. The NCI says the median (middle) time from the first symptom to diagnosis is 2 to 5 months. A longer wait has not been linked with spread, surgery results or survival.

About 1 in 4 people already have spread (metastasis) when they are diagnosed. The most common places are the lungs, other bones and the bone marrow. Some people have back pain, or weakness or numbness in the arms or legs.

Treatment usually lasts many months. Chemotherapy lowers blood cell counts, which raises the risk of infection. The NCI says infections during cancer treatment can be life-threatening and need urgent care. Care teams often include surgeons, radiation doctors, nurses, social workers, psychologists and rehabilitation specialists. A fertility specialist may join, because some treatments can affect the ability to have children later.

St. Jude says most people who have limb-sparing surgery or an amputation do well over time. Some children need more operations to lengthen the limb as they grow. Other problems can appear months or years after treatment ends. These late effects can include heart problems, kidney damage, hearing loss, infertility and uneven limb growth after radiation to a growing bone. There is also a risk of a second cancer, such as leukemia or a sarcoma in an area that got radiation. Regular checkups after treatment look for these problems.

Ewing sarcoma can come back, most often within 2 years, but sometimes more than 5 years later. For this reason, scans continue for years after treatment. When it comes back, treatment usually uses different chemotherapy, with surgery or radiation to the new tumors. High-dose chemotherapy with the person’s own stem cells has also been used, but the NCI says there is no proof it works better than standard chemotherapy.

Ewing sarcoma is not treated with a donor stem cell transplant as standard care. When a stem cell transplant is used, it is autologous. The person’s own stem cells are collected before the high-dose chemotherapy and then given back. No registry donor is needed, and no donor search is part of the plan.

Donor (allogeneic) transplants have been tried for high-risk and returning Ewing sarcoma. Registry studies found no sign that donor immune cells attack Ewing sarcoma cells in a helpful way. Donor transplants also did not lead to better results than own-cell transplants. They also caused more complications. European transplant experts (EBMT) rate donor transplants for Ewing sarcoma as developmental in children and generally not recommended in adults. For children with solid tumors, they say donor transplants should be explored only within clinical trials at very experienced centers.

For families facing Ewing sarcoma, joining a blood stem cell registry is a way to help other patients, such as people with leukemia, rather than a need of their own.