MOLECULAR GENETIC FEATURES OF BREAST CANCER AND THEIR CLINICAL SIGNIFICANCE

Breast cancer is a biologically heterogeneous disease whose course and treatment depend on the molecular profile of the tumor. Aim: to summarize the molecular genetic features of breast cancer and their clinical significance. Materials and methods. An analytical review of the scientific literature was performed, with data systematized by molecular subtypes, hereditary and somatic alterations, and treatment implications. The molecular classification (luminal, HER2-enriched and triple-negative subtypes), the role of hereditary mutations (BRCA1, BRCA2, PALB2, CHEK2 and others), somatic alterations (PIK3CA, TP53, ESR1, HER2 amplification), epigenetic mechanisms and mechanisms of treatment resistance are described; the use of genomic profiling for prognosis and for choosing hormone, HER2-targeted, PARP-inhibitor and immune therapy is discussed. Molecular genetic testing is becoming an integral part of breast cancer management, allowing risk assessment, prognosis and personalized therapy, but heterogeneity, resistance and unequal access to testing remain major challenges.