Breast cancer is the most common malignant disease in women in developed countries in the world. Although the mechanism of breast cancer development has not yet been fully clarified, epidemiological research has identified various risk factors for the developmentof this disease, where the not genetic and genetic factors play a significant role. It was found that two groups of genes play a key role in inducing cancer, namely oncogenes and tumor suppressor genes. Today, ten tumor suppressor genes, involved in the regulation of genomic contents, are associated with breast cancer. These include TP53, BRCA1, BRCA2, ATM, RAD50, PTEN, APC, CDH1, RB and PALB2. Mutations in BRCA1 and BRCA2 genes are associated with family breast cancer syndrome, and represent a high risk of early breast cancer development. Although the functions of these genes differ significantly, they are all involved in DNA damage repair and maintainenc of genomic stability. Mutations occuring in tumor suppressor genes cause loss of their function and it is possible that this is the mechanism crucial to the development of breast cancer. In this paper I will describe in more detail the properties and functions of some tumor suppressor genes, their contribution to the development of breast cancer, as well as the role of hormones, external factors and the importance of tumor markers in the diagnosis and treatment of this malignant disease.