Up next for Sarcoma Awareness month is Ewing sarcoma. Ewing sarcoma is the second most common bone cancer in children and adolescents. It makes up about 2% of all childhood cancers. Approximately 300 children will be diagnosed with Ewing sarcoma each year in the United States. The most common age at diagnosis is 15 years and most kids are diagnosed between the ages of 12 and 18 years. Slightly more males and whites are diagnosed than girls and other ethnicities.
Patients with Ewing sarcoma often come to medical attention because of pain with or without an associated “lump or bump”. Ewing sarcoma can also cause low grade fever, fatigue and weight loss. X-rays of Ewing sarcoma in the bone are often described as ‘moth eaten’ as seen below.
We can also evaluate Ewing sarcoma by using a fancy ‘sugar scan’ called a PET scan. This type of test shows how active tissues are in the body by measuring the uptake of a glucose (sugar) tracer. Here is an example of a PET scan showing Ewing sarcoma in the thigh bone. You will also notice that the brain is very dark. This is because the brain is always active and utilizing sugar; it doesn’t mean the disease has spread there. I think this concept of tumors taking up sugar is where the myth comes of “starving” cancers by trying to eliminate sugar from the diet. As I discussed in this post, sugar is essential to survive and your body will always find a way to have sugar. The other dark spots you can see are the kidneys and the bladder. This is just the tracer being eliminated in the urine.
Nearly all Ewing sarcoma tumors have a chromosomal translocation involving the EWSR1 gene. The two most common translocation partners are FLI1 and ERG, which account for approximately 95% of translocation partners in EWS. This abnormal chromosome swap is the reason the cancer develops. Unlike the BCR-ABL translocation that is found in leukemia, to date, we haven’t been able to find a good drug like Gleevec to target this chromosome change. Being able to effectively target this translocation is the holy grail of Ewing sarcoma, and many groups have worked for decades to try to solve this problem.
Tumor staging and treatment
Similar to osteosarcoma, Ewing sarcoma is classified as metastatic (the disease has spread beyond the original location) or not. About 25% of patients will be diagnosed with metastatic disease. The most common site of metastasis is the lungs, followed by other bones, bone marrow, and very rarely lymph nodes.
The standard treatment of Ewing sarcoma includes chemotherapy and either surgery or radiation. All patients with tumors in the lungs will receive lung radiation in addition to any radiation performed at the original site of the tumor.
Outcomes
The outcomes for children and adolescents with Ewing sarcoma depend on metastatic status and site of disease. Patients with localized disease have a 5 year overall survival rate of approximately 70-75%, but if the disease has spread, the survival drops 15-30%. Patients with tumors in the arms and legs have better outcomes compared to those patients that have tumors in the pelvic bones.
