ALK and lung cancer: Various molecular-targeted drugs for treating patients with advanced-stage non-small-cell lung cancer (NSCLC) that are tailored for specific driver gene mutations, including epidermal growth factor receptor gene (EGFR), fusions of echinoderm microtubule-associated protein-like 4 and anaplastic lymphoma kinase (EML4/ALK), c-ros oncogene 1 (ROS1), and v-raf murine sarcoma viral oncogene homolog B1 (BRAF), improve prognosis better than conventional cytotoxic chemotherapy [1,2,3,4,5].