Inclusion Criteria:  Signed informed consent Male or female, age equal to or greater than 40 years old and less than 75 years old Blood sample was collected before surgery for the detection of cfDNA methylation and other biomarkers Lung cancer patients diagnosed for the first time within 42 days before blood sampling without any anti-tumor treatment; or patients who are highly suspected of lung cancer through imaging evaluation or other routine clinical diagnosis and confirmed by tissue biopsy or surgical specimens within 42 days after blood sampling The subject has not received any local or systemic anti-tumor therapy before blood collection, including (not limited to) any surgery, local or systemic radiotherapy and chemotherapy, targeted therapy (including anti-angiogenesis), immunotherapy, cancer vaccines and hormone therapy, etc.  Exclusion Criteria:  Unable to obtain sufficient and qualified blood samples Female subjects who are pregnant or breastfeeding Patients who have received organ transplantation or non-autologous bone marrow or stem cell transplantation Patients who have received blood transfusion within 7 days before blood sampling Patients who have received anti-infection treatment within 14 days before blood collection Patients who have receiving anti-tumor drugs for other diseases within 30 days before blood collection, such as methotrexate, cyclophosphamide, mercaptopurine, chlorambucil, tamoxifen, etc. Patients who suffered from other malignant tumors or multiple primary tumors at the same time Pathological confirmed benign lesions by tissue biopsy or surgery Insufficient sample for a confirmed pathological diagnosis Lung cancer patients with ground glass nodules on CT imaging.