Breast cancer is more solitary and most breast cancer patients present with a lump in one breast. The lump is small at the beginning, but the diameter of the lump increases with time and the border is not clear, it may not have any shape or it may be burr-like around, there is pain when pressing, and the lump invades into the chest wall, making the lump fixed or the lump leads to lymphatic obstruction, causing the skin to be orange peel-like or the axillary lymph nodes to be enlarged. After clear diagnosis, it is necessary to perform unilateral mastectomy with complete clearance of axillary lymph nodes, i.e. modified radical mastectomy, after which a drain is routinely placed and the wound is sutured, and the patient can be discharged from the hospital in about one week.