Breast cancer can be divided into different pathological histological classifications and different histological grading according to pathological types, as follows: 1. WHO histological classification: Breast cancer can be divided into two categories: non-invasive breast cancer and invasive breast cancer, where non-invasive breast cancer includes ductal carcinoma in situ and lobular carcinoma in situ. Invasive breast cancer includes invasive ductal carcinoma, invasive lobular carcinoma, medullary carcinoma, papillary carcinoma, and so on. Among them, invasive ductal carcinoma is the most common, accounting for about 65%-80%.2. Histological grading: Breast cancer can be divided into three levels according to different histological grading, which are represented by Roman numerals Ⅰ, Ⅱ and Ⅲ. The histological grading is based on the formation of glandular ducts, the polymorphism of the nucleus, and the nuclear schizophrenic count of the breast cancer tissue. Grade I represents highly differentiated, grade II represents moderately differentiated, and grade III represents poorly differentiated, with grade I, or highly differentiated breast cancer, having the best prognosis.