There is no strict distinction between intraductal breast cancer and ductal carcinoma, only the degree of infiltration is different. Intraductal carcinoma of the breast is known as intraductal carcinoma in situ of the breast, which is the abnormal proliferation of intraductal cells in the breast ducts, but does not exceed the surrounding basement membrane lesions, and it is one of the best pathological types of breast cancer, which belongs to the early stage of breast cancer, and has a relatively good prognosis. Most of the ductal carcinomas develop from intraductal carcinoma of the breast, and the scope of the lesion will be a little bit larger; intraductal carcinoma of the breast may grow out of the duct in the late stage with the spread of the tumor; and the site of the growth of ductal carcinoma of the breast may be in the duct or outside of the duct. Both intraductal breast cancer and ductal cancer will threaten patients’ life and health, once diagnosed, they should go to regular hospitals for standardized treatment as soon as possible.