The incidence of lung cancer has ranked first among malignant tumors, and in recent years, more and more people are found to have nodules in their lungs during medical checkups, so many people wonder if they are suffering from lung cancer. In this regard, there are benign and malignant lung nodules, among which benign nodules account for 70%-80%, and about 20%-30% of small non-calcified lung nodules are precancerous lesions, therefore, not all lung nodules need to be removed surgically. Most of the small nodules in the lung are benign. 2/3 of the patients treated by thoracic surgery are early-stage lung cancer, basically precancerous lesions or carcinoma in situ detected by low-dose spiral CT during physical examination, and most of the small nodules in the lung are within 2 cm, and there are often even patients who come to the doctor with less than 1 cm. When lung nodules are within 2 cm, most people have no symptoms. If they have persistent cough, blood in sputum, or feel chest pain, the disease should be at an intermediate or advanced stage. The U.S. has included low-dose spiral CT screening for early-stage lung cancer in health insurance, and the clinical cure rate for lung cancer within 2 cm is over 80%. Therefore, it is recommended that people over 45 years of age, or those with a family history of high-risk disease, be able to have low-dose spiral CT screening for early lung cancer once a year. 70-80% of lung nodules are benign and only 20%-30% of non-calcified lung nodules are precancerous. The differential diagnosis of pulmonary nodules is a very important task for clinicians. Benign lesions of pulmonary nodules include infectious diseases such as tuberculosis and fungal infections, inflammatory diseases such as rheumatic immune diseases, pulmonary edema, pulmonary fibrosis, etc. We are a large country with tuberculosis, and some people have contracted tuberculosis without developing it, but these people may be left with hard nodular lesions in their lungs, which are common on chest radiographs. Smoking is still the primary risk factor for lung cancer, however, non-smoking lung cancer is more common in women. In the 1980s and 1990s, 8 out of 10 lung cancer patients were men, and now the ratio is 50/50 between men and women. The reason for this phenomenon is mainly because women inhale more fumes when cooking, and even non-smoking women usually experience second-hand smoke pollution. In addition to smoking, various kinds of pollution should not be ignored, such as air pollution, including living room decoration pollution, automobile exhaust pollution, barbecue food pollution, etc., are also risk factors for lung cancer. Nowadays, a special type of lung lesion with high prevalence in Asian population deserves attention, which appears as ground glass-like density shadow on CT. This is more common in female patients, and a significant proportion of them are early stage lung cancer, which is more dangerous than solid nodules. However, such nodules develop very slowly, and some of them even remain unchanged for many years. Therefore, it is important not to have too much psychological pressure when it is found, and treatment can be provided according to the specific situation. How to confirm the diagnosis from small nodules to lung cancer. What should I do if I find a small lung nodule? Benign lung nodules usually grow slowly. If a small nodule is around 0.5 cm, then observation is the main focus, with CT review once in 3-6 months and insist on follow-up, usually for 3 years, and annual physical examination if there is no change afterwards. If a nodule grows from 0.5 cm to 0.8 cm within a few months, and there is a tendency of gradual increase, you must consult a specialist whether to do a minimally invasive thoracoscopic resection, which is currently able to both confirm the diagnosis and play a therapeutic role. What steps are needed from small nodules to confirmed lung cancer diagnosis is a question that many readers are wondering. If the small nodule is still increasing in size after the preliminary observation, when the doctor highly suspects that this nodule is lung cancer, the first step will be anti-inflammatory treatment, “since some small lung nodules look like present cancer, but once the anti-inflammation it disappears, then this is a transient nodule and lung cancer is excluded”, and if the nodule still does not shrink after the anti-inflammation, we have to If the nodule does not shrink after anti-inflammation, the possibility of inflammation is ruled out and the next step is minimally invasive surgery.