Following these guidelines, the genes whose alterations have to be tested have been grouped into three different categories: (a) a set of genes that must be offered by all laboratories, that test lung cancers, including EGFR, ALK and ROS1; (b) a second set of genes that should be included in any expanded set of genes, including BRAF, MET, RET, ERBB2 and KRAS; (c) KRAS testing may be performed also as a single-gene test to exclude patients from expanded panel testing [352,353]. The gene discussed is ROS1; the disease is lung cancer.