Lung adenocarcinoma stage III belongs to the stage of middle and advanced lung cancer, at this stage, comprehensive treatment should be done, mainly radiotherapy and chemotherapy. Lung adenocarcinoma is one of the common malignant tumors and belongs to non-small cell lung cancer. Lung adenocarcinoma stage III means that the cancer cells have further metastasized to the mediastinum or extrapulmonary lymph nodes, and it belongs to intermediate and advanced lung cancer stage. Most patients with stage III lung adenocarcinoma have lost the chance of surgery, at this time, they should have comprehensive treatment, mainly radiotherapy and chemotherapy, and commonly used chemotherapy regimens include pemetrexed plus platinum, docetaxel plus platinum, gemcitabine plus platinum, etc. Specific treatment regimens should be based on the patient’s own condition. The specific treatment plan should be customized by professional doctors according to the patient’s own situation. Patients are advised to quit smoking and drinking, eat less stimulating food, take a light diet and eat more fresh vegetables and fruits. At the same time, actively cooperate with the doctor’s treatment, in order to prolong the survival period.