The common causes of weak sweat in advanced stage of lung cancer are weak constitution, endocrine environment disorder, tumor fever, etc., which are not good. 1. Weakness: In advanced stage of lung cancer, many patients have poor appetite, emaciation, malnutrition, hypoproteinemia, anemia, etc. With weak physique, the body is easy to sweat. 2. Disordered endocrine environment: In advanced stage of tumor, endocrine system is affected and dynamic balance is broken, so low calcium and low blood sugar are easy to appear, which will lead to sweating, and need to be corrected by calcium and sugar supplementation in time. 3. Tumor fever: some patients with advanced stage of lung cancer are prone to tumor fever, body temperature is usually not more than 38℃, without chills, and they will sweat when and after the heat subsides. Patients with advanced stage of lung cancer are recommended to take active treatment, keep a good mind, pay attention to rest, and take care of supplemental nutrition in diet.