KRAS and cancer: Regardless of gender, lung cancer is the leading cause of cancer-related deaths worldwide.[1] Kirsten rat sarcoma (KRAS) mutation have been the most common driver gene mutation in non-small cell lung cancers (NSCLC) worldwide, accounted for 20% to 25% in lung adenocarcinoma.[2–4] In Taiwan, however, KRAS mutation was found in only 3.3% to 5.0% of patients, while the epidermal growth factor receptor (EGFR) and as well as the rearrangement of the anaplastic lymphoma kinase (ALK) gene were more common.[5,6]