This study through the detection of EGFR、ALK、ROS1、KRAS、HER2、BARF、NTRG1 seven ctDNA and exosome RNA in the blood and alveolar lavage of lung nodules patients and heavy smoking healthy population. If the results of ctDNA test is positive, the target nodule is malignant; if the reaults of ctDNA teste is negatie but exocome RNA is positive, the target nodule is also malignant. If the results of both tests are negtive, the target nodule is recognized as benign. The purpose is study the sensitivity, specificity and diagnostic accuracy of ctDNA and exosome combined detection in the identification of benign and malignant pulmonary nodules. Besides, the diagnostic efficacy of different specimens including blood and alveolar lavage in the identification of benign and malignant pulmonary nodules is also studied.

Pulmonary nodules are round or irregular shape lesions with a diameter of less than or equal to 3cm. 10% lung nodules will become lung cancer, and lung cancer is evolved from small nodules.

Liquid biopsy is an effective and noninvasive means to assist in the early diagnosis of lung cancer, including circulating tumor cell、exosome and ctDNA detection. CtDNA is used to detect DNA fragments relesased to plasma by cracking or apoptotic tumor cells. Exosomes are derived from living cells, and researchers found that exosome nucleic acid detection of living cells may be closely related to the dynamic development of tumors.

This study through the detection of EGFR、ALK、ROS1、KRAS、HER2、BARF、NTRG1 seven ctDNA and exosome RNA in the blood and alveolar lavage of lung nodules patients and heavy smoking healthy population. If the results of ctDNA test is positive, the target nodule is malignant; if the reaults of ctDNA teste is negatie but exocome RNA is positive, the target nodule is also malignant. If the results of both tests are negtive, the target nodule is recognized as benign. The purpose is study the sensitivity, specificity and diagnostic accuracy of ctDNA and exosome combined detection in the identification of benign and malignant pulmonary nodules. Besides, the diagnostic efficacy of different specimens including blood and alveolar lavage in the identification of benign and malignant pulmonary nodules is also studied.

Inclusion Criteria:

Age ≥18 years old; The diameter of pulmonary lesions is 0.5-3cm in chest CT within 3 months; Healthy patients in normal control group had a smoking index ≥400; Patients who are eligible and intend to bronchoscopy.

Exclusion Criteria:

The patient received blood transfusion within 1 month； Patients suffer from autoimmune diseases, including but not limited to systemic lupus erythematosus, rheumatoid arthritis, sjogren's syndrome, etc； Patients with cardiopulmonary dysfunction or other taboos, not suitable for bronchoscopy; Patients refused to participate in this clinical trial; The investigator considerates that the patient has other conditions that is unsuitable for this clinical trial.

Our study population include 2 groups: pulmonary nodules group and healthy people group.