Impact of Airway Mucus Plugs on Secondary Pulmonary Fibrosis in COPD Patients: A Single-Center Case-Control Study

Inclusion Criteria: * ① Age ≥ 18 years old; * Planned radical resection for lung cancer, with postoperative pathological diagnosis of primary lung cancer; * During surgery, non tumor lung tissue at a distance of ≥ 5 cm from the tumor edge can be obtained; ④ Case group: Preoperative pulmonary function examination confirmed diagnosis of COPD (FEV ₁/FVC\<0.70); ⑤ Control group: Preoperative lung function was normal (FEV ₁/FVC ≥ 0.70), with no history of COPD; ⑥ The subjects are able to understand and sign the informed consent form Exclusion Criteria: * ① Clear presence of other interstitial lung diseases (ILD) or idiopathic pulmonary fibrosis before or during surgery （IPF）、 Fibrosis after pneumoconiosis or tuberculosis; * Active pulmonary infections (such as bacterial pneumonia, fungal infections, active tuberculosis); * Having received neoadjuvant radiotherapy or chemotherapy, which may affect the morphology or molecular results of distal lung tissue; ④ Combined severe immunodeficiency or long-term systemic immunosuppressive therapy (such as glucocorticoids ≥ 20 mg/d, More than 4 weeks); * Merge with other serious systemic diseases (such as advanced heart failure, end-stage renal disease), affecting study compliance or Survival expectation; ⑥ Pregnant or lactating women; ⑦ Refusing to sign the informed consent form or deemed unsuitable by the researcher to participate in the study.