ROS1 and cancer: In general, cancer tumorigenesis relies on the accumulation of mutations and is thought to be fueled by driver mutations that confer a growth advantage.12 Alterations in genes such as EGFR, KRAS, ALK, MET, HER2, ROS1, and RET have been shown to promote non-small cell lung cancer (NSCLC) formation and are currently targetable for cancer treatment.13,14 However, tumor next generation sequencing now allows us to better understand the passenger mutations as well.