Invasive carcinoma of breast with mucus secretion is mucinous carcinoma of breast, which may be caused by heredity, environment, diet and other factors, and patients may have symptoms such as local itching and pain. Mucinous carcinoma of the breast is a rare and special type of breast cancer originated from the breast. Under the microscope, a large amount of extracellular mucus can be seen, and different shapes of cancerous tissues are floating among the mucus, and the tumor grows slowly, and metastasis is relatively rare, and the prognosis is better than that of other types of breast cancer. If a patient has breast mucinous carcinoma, it may be caused by heredity, or it may be caused by long-term exposure to radiation, because breast tissues are more sensitive to it, so breast mucinous carcinoma has a higher chance of occurrence. High-fat food is also one of the factors causing breast mucinous carcinoma, which promotes the production of estrogen and does not have enough progesterone to fight against it, thus increasing the chance of developing breast mucinous carcinoma. Mucinous carcinoma of the breast may be manifested by nipple discharge and recurring dampness around the nipple, as well as localized itching, pain, and lumps in the breast glands. If there is mucinous carcinoma of the breast, patients are advised to go to the hospital in time and undergo relevant examinations for clear diagnosis.