Among oncological diseases of women, breast cancer is a widespread disease. It should be noted that the disease is heterogeneous in many clinical and pathological features. The development of breast cancer is associated with many factors, and it is difficult to identify any specific risk factor. The studying the expression and epigenetic mechanisms of genes associated with breast cancer, it is possible to effectively combine epigenetic therapy with the existing one in clinical practice (chemotherapy, hormonal therapy, etc.) and accordingly, the treatment of disease is significantly improved.