Thus, Uta Dirksen presented first results from the “EFACT” (EWSR1-FLI1 sequence analysis from ctDNA) study ancillary to the European clinical Ewing sarcoma trials Ewing2008 and Ewing 2012, while Marc Ladanyi presented data based on the MSK-IMPACT program at Memorial Sloan Kettering Cancer Center, which provided proof of principle for detection of circulating tumor (ct) DNA in the plasma preceding clinically overt relapse of Ewing sarcoma. This evidence concerns the gene EWSR1 and Ewing sarcoma.