ROS1 and non-small cell lung carcinoma: In fact, in some cases, they display a close correlation with a specific tumor subtype, thus representing a diagnostic marker (e.g., FLI1/EWS in Ewing Sarcoma), while in others they are endowed with a prognostic value, providing a risk stratification (e.g., the presence of gene fusions in embryonal rhabdomyosarcoma), or they could represent a potential therapeutic target (e.g., ALK and ROS1 in non-small cell lung cancer (NSCLC)) [13].