Breast cancer is a common malignant tumor that occurs in the breast. The causes of its occurrence are very complicated, but can be broadly classified as follows: 1) related to early menstruation or late menopause in women; 2) related to obesity and sedentary lifestyle; 3) related to high mental stress, etc. Both men and women can develop breast cancer, but the proportion of men is much lower than that of women, the ratio is about 100:1 for women than men, which is the basic situation of breast cancer. The occurrence of breast cancer may be related to genetic factors, for example, the probability of developing breast cancer increases significantly if the patient’s first-degree relatives, i.e. his mother or siblings, have the disease.