Breast cancer is classified according to histology as in situ cancer and invasive cancer. Carcinoma in situ is the earliest type and does not require chemotherapy. Carcinoma in situ is divided into intraductal carcinoma and lobular carcinoma in situ. Invasive carcinoma includes invasive ductal carcinoma and invasive lobular carcinoma. There are other types of breast cancer, such as medullary carcinoma, mucinous carcinoma, papillary carcinoma, and tubular carcinoma. According to immunohistochemistry, there are also Luminal A type and Luminal B type. Then there is triple negative breast cancer. Therefore, the prognosis of breast cancer is highly related to the classification and staging.