Background. In recent years, the prognosis of survival after treatment for breast cancer (BC) has improved significantly, leading to an increase in the life expectancy of patients and the incidence of long-term side effects of therapy. reducing the risks of complications and developing a unified algorithm for diagnosing cerebral complications are necessary to improve the quality of life of patients.Objective. To correlate the CNS and endothelium damage biomarkers concentration and the functional connectivity of the brain in patients with newly diagnosed vestibulo-atactic syndrome (VAS) and without it in the late period of radical treatment of breast cancer.Design and methods. The study involved 21 patients with VAS in the late postoperative period after radical treatment of breast cancer, as well as a group of healthy volunteers — 17 people. Biomarkers were determined by ELISA. Functional MRI was performed.Results. An increase in markers of CNS damage and endothelial damage (ICAM, PECAM) was noted in patients with post-mastectomy syndrome (PMES) and VAS, compare with control group and PMES without VAS group. The processes of disorganization and the formation and strengthening of interand intrahemispheric connections were noted using fMRI.Conclusion. The development of novel diagnostics methods, including the use of fMRI and the determination of different biomarkers are promising for improvement of the VAS treatment effectiveness in patients with PMES.