The ineffective performance of taking Gefitinib is mainly manifested by the enlargement of the primary tumor or the emergence of metastasis. Gefitinib is mainly used for the treatment of non-small cell lung cancer with EGFR (epidermal growth factor receptor) mutation, which has considerable therapeutic effect, but is prone to drug resistance, which is mainly manifested by the continued growth of the primary tumor, including the persistence or aggravation of primary symptoms, such as coughing, coughing up sputum, fever, or respiratory difficulties, etc.; and the increase of the tumor volume in the chest CT. Gefitinib ineffectiveness or drug resistance is also manifested by the emergence of metastasis, such as intrapulmonary metastasis or the emergence of distant metastasis. Therefore, during the period of taking Gefitinib, it is necessary to review regularly, and if the phenomenon of ineffective or drug resistance occurs, it is necessary to consult a doctor in time, and change the treatment plan under the guidance of the doctor, so as to avoid delaying the condition.