Lung cancer can be divided into 4 stages. 1. Stage I Lung Cancer: Lung tumors less than 5 cm and without metastasis of cancer cells belong to Stage I Lung Cancer. 2. Stage II Lung Cancer: Lung tumors in 5~7 cm with no lymph node metastasis or only N1 lymph node metastasis belong to stage II lung cancer. 3. Stage III lung cancer: patients with N1, N2 or N3 lymph node metastasis belong to stage III lung cancer. 4. Stage IV lung cancer: if there is metastasis to distant organs, it is advanced lung cancer, that is, stage IV lung cancer, regardless of the size of the lung lesion or whether there is lymph node metastasis. Lung cancer patients should actively consult doctors, try to find and treat the disease as early as possible to avoid delaying the condition, and patients should not use medicines by themselves.