For most clinicians, even most oncologists, ROS proto-oncogene 1, receptor tyrosine kinase (ROS1) fusion lung cancer remains a rare entity never encountered in actual practice. Indeed, this molecular subset represents only about 1% of non-squamous non-small cell lung cancer (NSCLC) cases. However, the identification of this genomic alteration can be game-changing. Over the past decade, molecularly targeted therapies already in use for other cancer types, such as crizotinib (initially approved for ALK receptor tyrosine kinase [ALK]-positive lung cancer), were also found to have impressive efficacy against advanced ROS1-positive lung cancer. Radiographic response rates approach 80%, with median response duration nearing 3 years (1). By comparison, combinations featuring multi-agent chemotherapy and immune checkpoint inhibitors yield response rates under 50% and median response duration of 1 year in advanced lung cancer.