There are no studies showing that the severity of breast cancer is related to its location; the severity of breast cancer is mainly related to the type of pathology and the presence or absence of metastasis. Breast cancer is one of the most common malignant tumors in women, and its etiology is still unclear, among which estrone and estradiol have a direct relationship to the development of breast cancer. The degree of malignancy of breast cancer is related to the type of pathology and the presence or absence of distant metastasis, etc. The higher the degree of malignancy, the more serious the condition. However, no study has shown that breast cancer on one side is more malignant than the opposite side. Among various types of breast cancer, Paget’s disease of the nipple generally has a better prognosis, while inflammatory breast cancer is rare but develops rapidly, has a poor prognosis, and has a high degree of malignancy. Breast cancer can also develop local metastasis, lymphatic metastasis and blood line metastasis, and the condition of breast cancer patients with metastasis is more serious than that of patients without metastasis. The current treatment methods for breast cancer include surgery, chemotherapy, radiotherapy, endocrine therapy, targeted therapy and so on.