ROS1 and non-small cell lung carcinoma: Overall, these considerations suggest that, in addition to the three “must-be-tested” EGFR, ALK and ROS1 genes (currently together with the assessment of PD-L1 status by IHC), testing of NSCLC should be expanded to include all classes of genomic alterations (base substitutions, indels, CNVs, and rearrangements) and detect other potential molecular biomarkers that could aid in more effectively predicting the response to first-line TKIs alone or combined with other drugs.