The importance of selected biomarkers in the clinical practice of breast cancer patients

Breast cancer is considered the most commonly diagnosed tumors. Biomarkers used for the diagnosis and treatment of breast cancer are: tissue biomarkers (PR, ER, HER2, Ki-67) and serum biomarkers (CA15-3, CA125, CA27.29, CEA, cytokeratins). ECD HER2, metalloproteinases and leptin are emerging promising biomarkers for breast cancer. There is a growing need for personalized diagnostics based on tumor genome characterization, relying on liquid biopsy containing components such as CTC and ctDNA, cell-free RNA. Biomarkers can also be used use as a target for anti breast cancer treatment (PGRN and sortilin, AR, PD-1/PD-L1). Another potential fields of application of breast cancer biomarkers is monitoring of treatment side effects, such us inflammatory biomarkers causing cardiotoxicity, thyroiditis biomarkers (TSH, FT4, TPOab TgAb) in IrAE, NF-L and MCP-1 in ICI-associated neurotoxity. It is expected to develop new prognostic and predictive biomarkers that would provide accurate and reliable information for clinical application. Through the recognition of emerging biomarkers, it is possible to identify subgroups of patients who benefit from targeted therapies and managing treatment by monitoring side effects. However, these new biomarkers need to be validated and tested for their suitability before entering clinical use.