Detection of ALK and ROS1 rearrangements by IHC prescreening and FISH confirmation is the standard process for identifying patients with NSCLC eligible for treatment with tyrosine kinase inhibitors.18 FISH/IHC discordances are common in routine practice and decision‐making on treatment with targeted therapies remains complicated for these patients. This evidence concerns the gene ROS1 and non-small cell lung carcinoma.