1. Pathogenesis
1.1. Transcription factor EWS-FLI1
1.1.1. This transcription factor is produced in Ewing Sarcoma due to the chromosomal translocation of chromosome 11 and 22.
1.1.2. Transcription factors control which genes to switch on or off.
1.1.3. Expression of EWS-FLI1 results in cell death or arrests cell growth. Expression in tumor cell lines causes differentiation defects.
1.2. The cell of origin is unknown which makes treatment very difficult.
2. Risk Factors
2.1. Lifestyle-related
2.1.1. Since Ewing Sarcoma is a childhood/adolescent cancer, lifestyle-related risks do not play a big role in Ewing Sarcoma. Body weight, tobacco use, diet, and physical activity play major roles in adult cancers, but it takes years for these factors to influence cancer risk.
2.2. Race/Ethnicity
2.2.1. Ewing Sarcoma is more common in white people and less common among Asian Americans and very rare in African Americans.
2.3. Gender
2.3.1. Ewing Sarcoma is slightly more common amongst males than in females.
2.4. Age
2.4.1. Ewing Sarcoma is most common in the adolescent population and less common in young adults and children. This cancer is very rare in adults, however, Ewing Sarcoma can occur at any age.
2.5. Environmental
2.5.1. Ewing Sarcoma has no links to chemical, radiation, or other environmental exposures.
2.6. Genetics
2.6.1. Ewing Sarcoma is the result from chromosomal translocation, a gene change. However, this cancer is no inherited gene changes.
3. Incidence & Prevalence
3.1. Incidence
3.1.1. All ages: 1 case per 1 million people
3.1.2. 10-19 years: 10 cases per 1 million people
3.1.3. Much greater incidence in whites than in African Americans
3.1.4. The median age is 15 years and more than 50% are adolescent patients.
3.2. Prevalence
3.2.1. Each year, about 225 children and adolescents are diagnosed with Ewing Sarcoma.
4. Diagnostics
4.1. Blood Tests
4.1.1. A complete blood count is obtained to search for abnormal levels of white blood cells, red blood cells, and platelets. Abnormal levels can be a sign for tumor spread.
4.1.2. The liver and kidney can be checked for high levels of lactate dehydrogenase, which can signal the presence of a tumor.
4.2. X-Ray
4.2.1. This is performed if a lump on the bone does not subside. The tumor can be visualized on an x-ray and can often tell if it is Ewing’s Sarcoma.
4.3. Computed Tomography - CT Scan
4.3.1. This test is used to see if the tumor has spread to the lungs by creating a cross-sectional image of soft tissues. Ewing Sarcoma metastasizes to almost every organ, so this test can determine to severity of metastasis.
4.4. Magnetic Resonance Imaging (MRI)
4.4.1. An MRI is conducted if an abnormality is found on an x-ray and can determine if it is a tumor or another type of bone damage. MRI scans help determine extent of a tumor which can help determine the type of treatment.
4.5. Position Emission Tomography (PET Scan)
4.5.1. A form of radioactive sugar is injected into the blood of the patient. The tumor cells will absorb the sugar and the scan will take pictures of the areas of radioactivity in the body.
4.5.2. This scan helps determine the spread of Ewing tumors and can find oother affected areas of the body. This scan is repeated multiple times during the patient’s treatment to monitor the cancer.
4.6. Bone Scan
4.6.1. A bone scan shows whether the cancer has metastasized to bones in other parts of the body. This scan shows the entire skeleton.
4.6.2. The scan will show “hot spots” in areas of active bone change. The hot spots can suggest the presence of cancer, but other diseases can also cause changes.
4.7. Biopsy
4.7.1. Imaging tests suggest Ewing Sarcoma, however, a biopsy of the tumor is the only way to be certain.
4.7.1.1. Excisional Biopsy
4.7.1.1.1. If the tumor is small, the surgeon can remove the entire tumor.
4.7.1.2. Incisional Biopsy
4.7.1.2.1. Surgical (open) Biopsy
4.7.1.2.2. Needle (closed) Biopsy
4.8. Bone Marrow Aspiration
4.8.1. This test is to determine whether the cancer cells have spread to the bone marrow. This test is not usually conducted to diagnose Ewing Sarcoma, but it may be performed to determine the spread in the bone marrow.
4.9. Immunohistochemistry
4.9.1. A biopsy sample is treated with antibodies that bind to substances found on Ewing tumor cells. Stains are added to the tumor cells change color and can be seen under a microscope.
4.10. Cytogenetics
4.10.1. This test uses chromosomes from the tumor cells and detects any changes while visualizing them under a microscope. Ewing Sarcoma always has chromosomal translocations on chromosomes 11 and 22.
5. Treatments
5.1. Chemotherapy
5.1.1. Typically the first step for treating Ewing Sarcoma. It involves powerful medicines to kill cancer cells. It may be injected into the bloodstream. Combination therapy uses more than one type of chemotherapy at the same time.
5.2. Surgery
5.2.1. Surgery is usually performed after weeks or months of chemotherapy. The chemotherapy should have reduced the cancer so the surgery can be effective.
5.2.2. Surgeons remove as much of the tumor they can and will sometimes graft bone to replace the diseased bone. Some patients may require amputation to ensure the tumore is completely removed.
5.3. Radiation Therapy
5.3.1. Radiation is used when surgery is not an option. Chemotherapy is used after to rid any remaining cells.
5.3.1.1. External Radiation
5.3.1.1.1. Uses machines outside of the body to deliver the high-energy X-rays.
5.3.1.2. Internal Radiation
5.3.1.2.1. Uses needles or catheters to transmit the radiation directly on the cancer.