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]. Here, FOXO1 is linked to alveolar rhabdomyosarcoma.