Definition
Ewing’s sarcoma is a cancerous bone tumor that may occur in any bone in the body and also in soft tissue (the latter of which is termed an extraosseous sarcoma). The most commonly affected areas include the pelvis, thigh, lower leg, upper arm, and chest wall.
The cancer most often strikes children and young adults, with puberty being the most common age of onset. During adolescence, Ewing’s sarcoma is found equally in boys and girls. In post-adolescent onset, the cancer is more common in males.
Ewing’s sarcoma occurs in approximately one in every 50,000 teenagers, accounting for around 30% of all bone cancers that occur in children. Prognosis is dependent upon the location of the tumor and whether the tumor has spread to other areas of the body.
Causes
The causes of Ewing’s sarcoma are not fully understood. Some potential contributing factors include:
- Chromosomal rearrangement that alters the genes (fusion of the EWS gene to specific transcription factor genes)
- Injury or trauma to the bone
- Prior high-dose radiation exposure
Risk Factors
A risk factor is something that increases your chance of getting a disease or condition. Because the causes of the cancer are unknown, risk factors are also not fully understood. The following factors may increase your chance of developing Ewing’s sarcoma:
- Having another congenital disease
- Having had another malignancy, particularly one treated with radiotherapy
Other factors:
- Ewing’s sarcoma is not an inherited condition. Having family members who have the cancer does not increase the likelihood of developing the cancer.
- Race: People who are of African American or Asian descent are at a significantly lower risk of developing Ewing’s sarcoma than Caucasians.
- Age—This tumor is more common among teenagers.
- Gender—This tumor is slightly more common among males.
Symptoms
Symptoms include:
- Pain, redness, and swelling surrounding the tumor
- Fever
- Weight loss and reduced appetite
- Fatigue
- Paralysis and incontinence (in cases where the tumor is near the spinal cord)
- Numbness, tingling, and paralysis (caused by compression of nerves by the tumor)
- Difficulty breathing if the tumor is in the chest wall
Diagnosis
Your doctor will ask about your symptoms and medical history, and perform a physical exam. You will be treated by a team of doctors which may include an oncologist (doctor who specializes in cancer), orthopaedic surgeon (doctor who operates on bones), and a radiation oncologist (doctor that works with radiation to kill cancer cells).
Tests may include the following:
- Bone scans —to detect presence of a tumor
- CT scan —a type of x-ray that uses a computer to look for cancer that has spread to the lungs
- MRI scan —a test that uses magnetic waves to make pictures of structures inside the body
- PET/CT scan —to evaluate the metabolic activity of tissue
- Blood tests—to determine abnormalities in the blood
- Biopsy —to determine if a tumor is malignant
Treatment
Treatment involves a combination of chemotherapy, surgery, and radiation. Typically patients are first treated with chemotherapy for 8-12 weeks, followed by a CT or MRI scan to evaluate the tumor. Depending upon the tumor size and location, either surgery or radiation follows. Chemotherapy then resumes for several months after surgery or radiation.
Chemotherapy
Chemotherapy drugs are used to kill tumor cells. The medications used to treat this tumor include vincristine (Oncovin) , dactinomycin (Actinomycin D) , cyclophosphamide (Cytoxan) , doxorubicin (Adriamycin) , ifosfamide (Ifex) , and etoposide (VePesid) . Your doctor will prescribe a combination of these drugs to be given over a set time. This usually means every 2-4 weeks for several months.
Surgery
Surgery may be used to remove the tumor, as well as rebuild the affected bone. Depending upon the location of the tumor, a bone graft or prosthesis may be needed. There are special types of prostheses that expand as the bone grows. Sometimes several surgeries are needed to make sure the limb functions properly.
Radiation Therapy
Radiation therapy uses high-energy x-rays to kill tumor cells. It may be used with surgery or instead of surgery. It is usually given over several weeks and is followed by chemotherapy.
Future Therapy
A combination of high-dose chemotherapy and stem cell transplant is being evaluated at certain cancer centers. This combination therapy is typically used in cases where the tumor is very resistant.
Targeted chemotherapies focused on the rearranged genes and their products in Ewing’s sarcoma are being actively investigated.
Prevention
Ewing’s sarcoma occurs for unknown reasons. There are currently no preventive measures to reduce the risk of developing the cancer.