Heterogeneity is one of the characteristics of breast cancer. Although most of the studies agree with the monoclonal origin of spontaneous tumor

due to multiple division and proliferation

epigenetic and genomic changes in the process of occurrence and development

cells present different phenotypes and biological characteristics. These differences are reflected in tissue type

differentiation degree

cell proliferation rate

invasion and metastasis abilities

therapeutic response and many other aspects. The precise implementation of individualized medical treatment must treat the different molecular types represented by different histology and molecular characteristics differently and consider the existence of different cell subsets in the same tumor tissue. This article reviewed the mechanism and research progress of breast cancer heterogeneity in order to facilitate the clinical development of breast cancer precision medicine.