Lung cancer patients’ stomach pain may be caused by the following reasons: 1. abdominal metastasis, lung cancer may have systemic metastasis in advanced stage, although metastasis to abdominal cavity is rare, once metastasis occurs, it may lead to obvious abdominal pain, diarrhea and other digestive symptoms. In addition, abdominal metastasis may also lead to intestinal obstruction due to compression of the intestine, which may cause severe abdominal pain and vomiting and require immediate treatment to relieve the obstruction.2. Spontaneous peritonitis, lung cancer patients may often suffer from large amount of peritoneal fluid due to peritoneal metastasis or hypoproteinemia. The most common side effects of these platinum agents are gastrointestinal symptoms, including abdominal pain, nausea, vomiting, etc. 4. other rare causes, such as pulmonary embolism, intestinal vascular embolism, etc. The blood of cancer patients is in a hypercoagulable state, and blood clots are easily formed when the patients are bedridden for a long time with little exercise. The mesenteric artery thrombosis in the abdomen can cause significant abdominal pain or even intestinal necrosis.