Gefitinib is a targeted drug for advanced non-small cell lung cancer combined with EGFR gene mutation. The main side effects of gefitinib are causing rash and liver function impairment. If non-small cell lung cancer combined with EGFR gene mutation, the efficiency can reach more than 70%, and the progression-free survival time of patients is about 10 months. If progression occurs it can also be switched to oxitinib, which is a 3rd generation targeted drug. Therefore, gefitinib is a targeted drug with very good objective efficiency in advanced non-small cell lung cancer. However, patients with non-small cell lung cancer must have genetic testing before using Gefitinib to prove that there is a genetic mutation in EGFR before using this drug is effective.