Abstract: 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.

Key words: Breast cancer, Tumor heterogeneity, Clinical significance, Triple-negative breast cancer, Heterogeneity of tumor microenvironment