The importance of testing for other biomarkers, such as ALK, has already been quantified in Spain by Nadal et al. [23], however, it has not been quantified for the determination of a less prevalent biomarker such as ROS1. For this reason, the main objective of this analysis was to quantify the clinical and economic impact of ROS1 determination in patients with advanced NSCLC in Spain, comparing a testing ROS1 strategy with sequentially testing ROS1 in addition to EGFR and ALK versus a no-testing ROS1 strategy. The gene discussed is EGFR; the disease is non-small cell lung carcinoma.