Ewing Sarcoma

What is Ewing Sarcoma?

Ewing sarcoma is a type of cancer that grows in bones or in the soft tissue around bones. It often occurs in the leg, pelvis, ribs, or arm. Although Ewing sarcoma is very rare, it is the second most common type of pediatric bone tumor. About 200 children and young adults are diagnosed with Ewing sarcoma in the United States each year. 

Ewing sarcoma often arises in the bone. However, a small percent of patients develop tumors outside the bone (extraosseus). 

Ewing sarcoma is most often seen in older children and adolescents. If the cancer is caught early before the disease has spread, the chance of long-term survival is about 70%. Chance of cure is much lower if the disease has spread.

Ewing Sarcoma Causes and Risk Factors

It is not known why Ewing sarcoma develops in some children, but certain factors may increase risk including age, gender, and ethnicity. 

• About half of Ewing sarcoma tumors are diagnosed in older children and teens 10-20 years of age. 
• Ewing sarcoma occurs slightly more often in males than females.
• Caucasians have a higher risk of Ewing sarcoma compared to African-American and Asian-American children.
• Cancer survivors who were treated with radiation therapy have a higher risk for developing Ewing sarcoma.
• Ewing sarcoma does not seem to be passed down in families.

Ewing Sarcoma Symptoms

Symptoms of Ewing sarcoma depend on where the tumor is located. Common signs and symptoms of Ewing sarcoma include:

• Swelling, lump, and/or pain around the tumor site
• Fever
• Bone pain, especially during physical activity or at night
• Limping or problems walking 
• Bone that breaks without a reason

Pain may worsen over weeks or months and may cause the child to wake up at night. Because the symptoms of Ewing sarcoma can be mistaken for normal pains or injuries of childhood, it can take a while before a diagnosis is made.

Ewing Sarcoma Diagnosis

Several types of procedures and tests are used to diagnose Ewing sarcoma. These include:

• A health history, physical exam, and blood tests to learn about symptoms, general health, past illnesses, and risk factors. 
  • A complete blood count (CBC) will test the number of red blood cells, white blood cells, and platelets in the blood. 
  • Doctors will also check the level of lactate dehydrogenase (LDH), a substance in the blood that may be elevated in Ewing sarcoma.
• Imaging tests to look for tumors and help determine other tests that are needed. 
  • An X-ray of the bone.
  • A CT scan of the chest is used to see if Ewing sarcoma has spread to the lungs.
  • An MRI is used to assess the tumor and assist in planning surgery.
  • Full body imaging using bone scans or PET scans is used to look for cancer in bone and other areas of the body.
• Bone marrow aspiration and biopsy to see if cancer has spread. Doctors will obtain bone marrow sample by inserting a thin, hollow needle into the hipbone. A pathologist will view the bone marrow under a microscope to look for signs of cancer.
• A biopsy of the tumor to make a correct diagnosis. In a biopsy, the doctor removes a small amount of tissue from the tumor. The cells are then examined with a microscope to look for signs of cancer. An incisional biopsy or core needle biopsy may be used depending on tumor location. Ewing sarcoma tumor cells appear as small, round, blue cells under a microscope.

Ewing Sarcoma Staging

Ewing sarcoma is usually described as either localized or metastatic. Localized disease means that there is a tumor in only one place in the body. Metastatic Ewing sarcoma means that the cancer has spread to other places, such as the lungs, bones, or bone marrow.

Approximately 25% of patients have metastatic disease at diagnosis. About half of those patients have spread of disease to lungs at diagnosis.

Ewing Sarcoma Prognosis

The chance of recovery from Ewing sarcoma depends on several factors:

• Size and location of the tumor
  • Large tumor size is associated with worse outcome. 
  • Cancer located in the pelvis, ribs, or spine is harder to treat.
  • Patients with Ewing sarcoma tumors in soft tissue (extraosseus) tend to do better compared to patients with tumor arising in the bone.
• Patient age and gender
  • Younger patients (under age 15) tend to do better compared to older patients.
  • Girls tend to have a better prognosis compared to boys.
• Whether the cancer has spread (metastasized) to or other parts of the body (metastatic disease). Patients with metastatic tumors in the lungs do better compared to patients with metastatic tumors in the bones or lymph nodes.
• How responsive the tumor is to chemotherapy or radiation therapy
• If the cancer is recurrent (has come back)

Patients with a single, localized Ewing sarcoma tumor that can be completely removed with surgery have 70% chance of long term cure. Patients who have metastatic disease in which the cancer has spread to distant parts of the body at diagnosis, (metastatic Ewing sarcoma), the chance of survival is 15-30%, depending on the location of the metastatic disease. The prognosis for patients with recurrent Ewing sarcoma is poor, and chance of cure is approximately 10%-15%.

Patients with recurrent Ewing sarcoma often develop new tumors within the first 2 years from diagnosis. This most often occurs as new nodules in the lungs. Patients who have “early recurrence” within 2 years from diagnosis are much more difficult to cure than those who have “later recurrence”.

Ewing Sarcoma Treatment

When Ewing sarcoma is diagnosed, it is usually first treated with chemotherapy followed by surgery and/or radiation therapy. New treatments including targeted therapy and immunotherapy are also being studied in clinical trials. 

There are 3 main goals of treatment for Ewing sarcoma:

1. Shrink the primary tumor and kill any circulating cancer cells with systemic chemotherapy
2. Remove the primary tumor with surgery and/or radiation
3. Treat any remaining cancer with chemotherapy to reduce risk for recurrence

Life after Ewing Sarcoma

Monitoring for Ewing Sarcoma Recurrence

Ewing sarcoma can recur years into survivorship. However, recurrence in Ewing sarcoma is most common (80%) within the first 2 years after treatment ends. The tumor can come back in the same place (local recurrence) or in another part of the body (distant recurrence).

Patients will receive follow-up care to screen for recurrence for a long time after treatment ends. The medical team will make specific recommendations for frequency and types of tests needed. Imaging tests usually include CT scans of the lungs, X-rays or MRI of the tumor site and PET or bone scans. If the patient has a history of Ewing sarcoma in the bone marrow, evaluation for recurrence may also involve testing the bone marrow.

Life after Limb-Sparing Surgery or Amputation 

Overall, most patients who undergo amputation or limb-sparing surgery do well over time. They report good physical function and quality of life. Follow-up care is important to ensure continued mobility. Patients should have an annual exam to check musculoskeletal function. It is important to make sure that there are no ongoing problems. Uneven limb length, changes in gait, joint issues, or other problems can cause chronic pain or disability. 

Patients who have undergone amputation should also have an annual exam to maintain the function of their prosthetic limbs. An orthopedic surgeon should evaluate patients with an endoprosthesis (bone graft and/or metal implant) at least once a year. Patients who have had limb-sparing surgery may require additional surgeries for limb lengthening until they reach adult height. 

Health after Ewing Sarcoma

Children treated for Ewing sarcoma are at risk side effects related to therapy. All survivors should continue to have regular physical checkups and screenings by a primary physician. For general health and disease prevention, survivors should adopt healthy lifestyle and eating habits. 

Survivors of bone cancer tend to be less active. Regular exercise is important to maintain health, fitness, and physical function. 

Survivors treated with systemic chemotherapy or radiation should be monitored for acute and late effects of therapy. Potential problems due to treatment may include hearing loss, heart problems, and kidney damage. 

Radiation to the leg can affect growth in that bone, causing it to be shorter. This may result in unequal leg length, or leg length discrepancy. There are different ways to treat this problem, depending on the severity. 

Serious chronic health conditions are present 25 years after diagnosis in approximately 25% of survivors, according to the Childhood Cancer Survivor Study. These conditions include second cancers (increased risk following exposure to radiation), congestive heart failure, infertility or complications during pregnancy, and end-stage renal disease or renal failure.