What is Ewing sarcoma?

Related conditions:
Primitive neuroectodermal tumor, peripheral primitive neuroectodermal tumor, Askin’s tumor, osteosarcoma

Definition:

Ewing sarcoma is a rare disease involving cancer cells found in bones and soft tissue. It usually occurs in the pelvis, ribs, arm bone (humerus), shoulder blade, or leg bone (femur). It gets its name from James Ewing, who in the 1920s first described the disease as being separate from other known types of cancers such as lymphoma or neuroblastoma. Ewing noticed that this type of cancer responded well to radiation. It belongs to a group of tumors sometimes called the Ewing family of tumors because of the close molecular relationship between these kinds of tumors.

Risk factors: More than 90 percent of people who develop this disease have an unusual rearrangement between chromosomes: A piece of chromosome 11 and a piece of chromosome 22 have switched places (called a gene translocation). However, this translocation is not inherited or passed on genetically, so family members of those affected with Ewing sarcoma have no more risk of developing the cancer than the general population does.

Male teenagers are most often diagnosed with this disease. The cancer is thought to be linked somehow to the rapid growth that occurs during puberty. Whites are more likely to develop this disease than are Asians and African Americans. MedlinePlus reported in 2014 that Ewing sarcoma is ten times as common in Caucasian children as in children of African or Asian descent.

Very rarely, Ewing sarcoma can develop as a secondary tumor in patients who have had radiation therapy for another type of cancer.

Etiology and the disease process: Because this cancer occurs most often during the teenage years, there may be a link between the onset of puberty and early stages of this disease.

Ewing sarcoma usually starts in a bone, though it can start in soft tissue. The most common starting place for these tumors is in the pelvis or in the leg bones. The tumors may then spread to the chest cavity, other bones, bone marrow, lungs, kidneys, or heart when tumor cells enter the bloodstream and travel elsewhere in the body. This disease may also spread to the central nervous system or lymph nodes, but this is much less common.

Incidence: This disease occurs most often in male children and teenagers, mostly between ten and twenty years old. However, female children and teenagers also develop this disease. In the United States, this cancer affects children less than three years of age at a rate of 0.3 per million and teenagers between the ages of fifteen and nineteen at a rate of 4.6 per million. People over the age of twenty-five rarely develop this type of cancer. In 2014 the American Cancer Society estimated that in North America each year about 225 new cases of this cancer are diagnosed in children and teens. These tumors make up about 30 percent of the bone cancers in children; the American Cancer Society reported in 2014 that about 1 percent of all childhood cancers are Ewing sarcoma.

Symptoms: Symptoms of Ewing sarcoma involve pain (which may be worse at night), swelling (especially when the tumor is located in the long bones of the arm or leg), redness, tenderness, stiffness, a mass that grows quickly and may feel warm, or a bone that breaks unexpectedly. Some patients have fever, fatigue, anemia, or weight loss. Numbness, tingling, or paralysis can also be symptoms if the tumor is located near nerves.

Screening and diagnosis: Because this disease is so rare, no screening is recommended. When Ewing sarcoma is suspected, doctors generally use x-rays to determine if there is a suspicious growth. A magnetic resonance imaging (MRI) scan or blood tests also may be helpful in making a diagnosis. If Ewing sarcoma is suspected, two additional tests are used to see if the disease has spread: a computed tomography (CT) scan, which usually includes the lungs to see if the disease has spread there, and a bone scan.

Ewing sarcoma may initially be mistaken for a bone infection (osteomyelitis) or another type of bone cancer (osteosarcoma). A sample of the tumor (biopsy) is necessary to confirm the diagnosis of Ewing sarcoma. A biopsy may be performed with a fine needle, taking only a small sample of the tumor, or by surgery, where all or a large part of the tumor is removed. Sometimes, bone marrow also is biopsied to determine if the disease has spread there.

There is no formal staging for Ewing sarcoma. Gauging the extent of this disease is done by simply determining whether the cancer has spread into other tissues.

Treatment and therapy: Ewing sarcoma is usually a very aggressive disease. By the time of diagnosis, nearly all patients with Ewing sarcoma have some spreading of the disease throughout the body. Most patients are treated with chemotherapy, sometimes before and after surgery, to ensure treatment of any tumors throughout the body.

Surgery or radiation may also be used at the local site of the main tumor if the tumor can be removed without damaging vital organs. Sometimes surgery involves removing bones, which can be replaced or rebuilt with artificial bones or bone grafts. With Ewing sarcoma, radiation therapy usually involves radiation that comes from a machine outside the body rather than from implanted radiation seeds. Radiation therapy can shrink large tumors to alleviate symptoms if the tumor cannot be removed with surgery.

Other types of treatment may include rehabilitation, including occupational or physical therapy. Patients may also need supportive care to help with side effects of chemotherapy, radiation, or surgery. Some patients may benefit from a transplant of blood stem cells or bone marrow.

Diagnosis of Ewing sarcoma usually occurs during the teenage years, sometimes an already turbulent period. Surgery may cause disfigurement during a period of life when looks are very important. Support groups in which teens meet other people with this condition may be especially helpful in dealing with the psychological trauma that this disease can cause.

Generally, patients with Ewing sarcoma benefit from treatment at a children’s hospital or medical center with doctors who have experience treating pediatric cancers.

Prognosis, prevention, and outcomes: The prognosis for patients with this disease depends on how far the disease has spread, the size and location of the main tumor, and how responsive the tumors are to chemotherapy. For patients who at diagnosis show no signs of the spread of the disease and choose an aggressive course of treatment involving chemotherapy, surgery, and radiation, survival rates at five years are 70 to 75 percent (ACS, 2014). However, at diagnosis, at least 15 percent of these patients already have cancer throughout their bodies, generally because symptoms are so vague and nonspecific. These patients have a five-year survival rate of 15 to 30 percent (ACS, 2014). Children under the age of ten, female children and teenagers, those with smaller tumors, and those who have tumors below the elbow or below the calf have the highest survival rates.

People who have had Ewing sarcoma need continual follow-up care. Even if the cancer is treated and its spread stopped, it often develops again in the place where it first arose and tends to spread throughout the body. Health issues may spring up later that are caused by the type of treatment given. These issues may involve heart and lung problems, slowed or decreased growth and development, and problems with sexual development. It is important for a patient who has had this disease to be regularly monitored for these types of concerns.

There is no known way to prevent Ewing sarcoma. However, not everyone with the gene translocation develops this disease. Scientists are investigating why the gene translocation causes the disease only in some people to see if there are ways to block this cancer from forming. Research is also under way to determine new and improved techniques for diagnosing this cancer earlier in the disease process.

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