New clinical practice guidelines for the treatment of lung cancer have been published by the Japan Lung Cancer Society in 2018 (Figure 1), with the first decision step for advanced NSCLC being based on (1) the detection of known oncogenic drivers including EGFR or BRAF mutations or ALK or ROS1 rearrangements; (2) the expression of programmed cell death-ligand 1 (PD-L1) in the tumor at a threshold level of ≥50%; and (3) the absence of driver mutations and a PD-L1 expression level of <50% or of unknown status. This evidence concerns the gene ROS1 and lung cancer.