Nipple bleeding one year after breast cancer surgery may be due to trauma, cancer recurrence, intraductal papilloma of breast. 1. Trauma: patients inadvertently collide with the nipple or scratch excessively, which breaks the nipple skin and causes capillary rupture in the nipple area, leading to the symptom of nipple bleeding. 2. Cancer recurrence: breast cancer is a kind of malignant tumor disease, which has the possibility of recurrence. When breast cancer recurs, it will lead to symptoms such as breast swelling, bloody nipple overflow, enlarged axillary lymph nodes and so on. 3. Intraductal papilloma: Intraductal papilloma can also lead to bloody nipple overflow, because there are more blood vessels in the ducts of the breast, and the wall of these blood vessels is thin, and with the increase of papilloma, it will lead to the rupture of blood vessels and cause nipple overflow. Bleeding nipple in breast cancer patients one year after surgery may also be related to breast hyperplasia, mastitis and other factors, they should go to regular hospitals as soon as possible to find out the cause and follow the doctor’s instructions to receive treatment.