Summary
This study evaluates whether circulating tumor deoxyribonucleic acid (ctDNA) in the blood can provide information about the chances of Ewing sarcoma or osteosarcoma coming back after treatment and locate specific genetic alterations. Identification of patients with Ewing sarcoma or osteosarcoma that has not spread to other parts of the body (localized) at high-risk of disease coming back after a period of improvement (relapse) after standard therapy remains challenging. While a range of prognostic (prediction of the course and outcome of disease processes) factors have been evaluated in these diseases, the presence of metastatic disease (has spread from where it first started [primary site] to other places in the body) remains the strongest adverse prognostic factor at diagnosis. DNA is the substance used to store genetic instructions used for growth, development and functioning of all living things. DNA instructs normal cells and cancer cells. New tests to analyze DNA can detect DNA in the blood that came from tumor cells, called ctDNA. While ctDNA can provide valuable information for patients with some types of adult cancers, it is not yet known whether ctDNA is important in cancers such as Ewing sarcoma or osteosarcoma that impact younger people. By studying patient blood samples, this study may help doctors find better ways to diagnose and treat Ewing sarcoma and osteosarcoma.