The increased permeability of the gastrointestinal mucosa is mostly seen in gastric and colon cancers due to necrosis and shedding of cancerous tissues, resulting in increased permeability of the corresponding gastrointestinal mucosa and loss of plasma proteins through leakage from the gastrointestinal tract. Normal gastric mucosal epithelial cells are differentiated from primitive new cells (stem cells), which are controlled by the body when to grow and when to die, and will not grow wildly out of control. Stem cells have various proto-oncogenes and oncogenes. In most cases, the characteristics of proto-oncogenes are not expressed and no carcinogenic substances are formed, so they cannot develop into cancer cells. Patients with increased permeability of gastrointestinal mucosa should pay attention to eating more foods rich in dietary fiber; eat more easily digestible, fine and soft semi-fluid foods. Avoid cold, spicy and other stimulating foods; avoid greasy and fried foods; avoid pickled and smoked foods. The treatment of increased permeability of gastrointestinal mucosa is mainly resection of the primary cancer tumor, and growth inhibitor analogues such as octreotide can also be applied, which is effective in controlling diarrhea. To overcome the psychological barrier, patients will show characteristic reactions when they learn they have cancer. At first, the patient may be in doubt, denial or despair, and may say “this must be a mistake” and “what is the use of treatment”. Emotional irritability, anxiety, depression, physical insomnia, anorexia and irritability, lack of concentration and uncertainty about the future.