Usually, lung adenocarcinoma stage IA3 refers to T1cN0M0, which belongs to early stage. It refers to the primary tumor with maximum diameter >2cm,≤3cm, and the lesion is confined to the lung and visceral pleura without involving the main bronchus; or confined to the wall of the tube, while the tumor is not accompanied by metastasis to regional lymph nodes and distant organs. The clinical stages of lung adenocarcinoma are Ⅰ, Ⅱ, Ⅲ and Ⅳ. Stage Ⅰ usually belongs to early stage, stage Ⅱ and Ⅲ usually belong to middle stage, and stage Ⅳ usually belongs to late stage. Stage I lung adenocarcinoma can be further divided into stage ⅠA1, stage ⅠA2 and stage ⅠA3. 1. Stage IA1: Lung adenocarcinoma is in stage IA1, its maximum diameter is less than 1 cm, limited to the lungs and visceral pleura, not invading the main bronchial tubes, without local lymph node metastasis. 2. Stage IA2: Lung adenocarcinoma is stage IA2, its maximum diameter is more than 1 cm and less than 2 cm, limited to the lungs and visceral pleura, and does not invade the main bronchus. 3. Stage ⅠA3: Lung adenocarcinoma in stage ⅠA3 means that the maximum diameter of the primary tumor is more than 2 cm and less than 3 cm, and the rest is the same as that of ⅠA1 and ⅠA2, only the volume of the tumor is different. For patients with stage IA3 lung adenocarcinoma, if they actively cooperate with doctors’ treatment, the 5-year survival rate is over 80% and the prognosis is good.