EGFR and cancer: Nevertheless, recent breakthroughs in the understanding of NSCLC biology have led to the discovery of specific genetic alterations, such as EGFR mutations, anaplastic lymphoma kinase (ALK), and ROS1 gene rearrangements, each of which identifies a distinct disease entity which has been termed ‘oncogene addicted’ in order to reflect its dependence on a single genetic ‘driver’ for proliferation and survival of cancer cells.