EGFR and adenocarcinoma: Gefitinib improves response rates, increases the time to progression and overall survival, and, in particular, shows better effectiveness for Asians, adenocarcinomas, and non-smokers or light smokers.[6] However, it is limited for controlling tumor progression because acquired resistance usually occurs within 6 to 12 months.[7,8] Many attempts have been made to overcome resistance, including using another target agent to bypass the signaling pathway blockade, combination chemotherapy or immunotherapy, or next-generation EGFR-TKI.