.Given the incremental importance of ROS1 testing in guiding the treatment of patients with NSCLC and the fact that ROS1 is an under-analyzed biomarker in comparison to ALK or EGFR in Spain [15], the main objective of our study was to assess if testing ROS1 is a cost-effectiveness strategy in Spain and also to raise the awareness of testing ROS1 according the clinical guidelines. The gene discussed is ALK; the disease is non-small cell lung carcinoma.