Lung cancer will have loose stools in advanced stage, mainly consider the following issues. Firstly, if lung cancer is in advanced stage, the whole body is more exhausted, there is hypoproteinemia, malnutrition, intestinal absorption disorder, and too much giving nutritious diet will lead to absorption disorder and produce symptoms of stool system. Finally, chemotherapy and other integrated treatments are given to lung cancer patients. Especially, chemotherapy is more damaging to the gastrointestinal tract and can easily damage the gastrointestinal mucosa leading to diarrhea. Patients who are given antibiotics and chemotherapy for a long time are prone to secondary infection, that is, fungal infection, which manifests in the intestine as intestinal malabsorption and leads to diarrhea. Therefore, the main consideration of why lung cancer in advanced stage may have loose stools is that the patient’s gastrointestinal tract is damaged. Especially for cachectic patients, despite intravenous nutrition therapy and oral nutrition solution, it will still lead to malabsorption and diarrhea.