Rectal malignancy is generally considered to be possibly caused by genetic factors, dietary factors and primary diseases such as long-term chronic inflammatory stimulation and rectal cancer. 1. Genetic factors: rectal malignancy may be caused by genetic factors. If the genes of normal cells are changed, the body gets susceptibility by heredity, and is stimulated by some kind of excitation factors, so that the tissue cells overgrow and develop into malignant changes. 2. Dietary factors: if you often eat high-fat food may increase the chance of malignant changes in the intestinal tract, the fiber content in the food is less, and the amount of stool will be reduced, which will lead to an increase in the concentration of malignant substances in the stool, the intestinal tract movement slows down, the malignant substances prolong the time of contact with the mucous membrane of the colon, the lack of fiber, the intestinal mucus secretion decreases, the intestinal mucous membrane in the alkaline environment of the exposure to increase the intestinal epithelium undergoes proliferative The intestinal epithelium undergoes proliferative changes, which in turn leads to malignant changes. 3. Long-term chronic inflammatory stimulation: such as schistosomiasis, amoebic dysentery, chronic dysentery, chronic non-specific ulcerative colitis, etc. For example, in patients with schistosomiasis of the rectum, the colorectal mucosa is stimulated by the deposition of eggs for a long time to produce necrotic detachment and the formation of ulcers, and polyps are formed on the basis of epithelial regeneration and proliferation, which will then lead to malignant transformation. 4. Rectal cancer: malignant tumor on rectal mucosa, which can lead to malignant transformation of rectum. After the occurrence of rectal lesions, timely medical treatment is needed to avoid malignant changes.