Sarcoma-specific fusion gene transcripts like EWSR1-ERG or EWSR1-FLI1 in EWS or PAX3-FKHR or PAX7-FKHR in alveolar rhabdomyosarcoma (aRMS) are providing a promising way to detect CTCs [25, 26]. This evidence concerns the gene PAX3 and alveolar rhabdomyosarcoma.