this single arm，open-label，multi-center study is aimed to evaluate the efficiency of icotinib in plasma ctDNA EGFR mutation-positive patients diagnosed with lung cancer

Inclusion Criteria:

• Clinical diagnosis of peripheral lung cancer, but the pathological diagnosis is not yet clear.
• Plasma EGFR mutations (EGFR 19del and/or 21L858R) positive (simultaneously detected by Super-ARMS, ddPCR and NGS，any positive).
• unavailable of radical surgery or radical radiotherapy.
• not previously received anticancer therapy like surgery, chemotherapy, radiation therapy, and biotherapy etc.
• Palliative radiotherapy for bone metastases is permitted, but there is no continuous toxicity associated with radiation therapy.
• Age 18-75 years old with performance status of 0 to 3.
• With a measurable disease(longest diameters >=10mm with Spiral computed tomography (CT)) according to RECIST Criteria.None of the lesions treated with radiotherapy could be used as target lesions.
• Adequate hematological, biochemical and organ functions.

Exclusion Criteria:

• Severe systemic disease out of control such as unstable or uncompensated respiratory,cardiac,liver,renal diseases.
• Evidence of interstitial lung diseases
• Evidence of any other significant clinical disorder or laboratory finding that makes it undesirable for the subject to participate in the study
• Other situations researchers think not appropriate to enter the group