Nowadays treatment of breast cancer (BC) is based on the tumor receptor status measured by the expression of ERs, PR, Her2/neu receptors. Our objective was to determine the gene expression of steroid receptors (ERα, ERβ, PR), cytokeratin 18 (KRT18) in malignant breast tumors of patients untreated and treated with neoadjuvant chemotherapy (NAC). BC samples were obtained after surgery of patients who were treated in the State Regional Oncology Center (Novosibirsk) from 2011 to 2014 (n = 122). We have found that the expression of ERα in patients after NAT decreased almost three times compared to the untreated group (p<0,05). To evaluate receptor status of BC, we used the semi-quantitative real-time RT-PCR method. It should be noted that mRNA level for ER might not always correlate with the protein level. In this regard, one of the objectives of this study was to conduct comparative analysis of immunohystochemical (IHC) results and ERα mRNA level obtained by RT-PCR. We have found that the results for ERα receptor expression measured by IHC and RTPCR match in 85.9% of cases. Besides, we determined the expression of KRT18, a marker of tumor cell proliferation, in patients under study with various tumor phenotypes. Our results also showed that the expression level of KRT18 decreased 3.2 times in tumor tissue of patients treated with NAC compared with an untreated group (p <0,05). We also evaluated the expression of KRT18 depending on the tumor phenotype. We have found that patients with ER+PR+ tumors had an increased level of KRT18 in both groups under study 2.7 times on average in comparison with ERPR+/-phenotype (p<0,05). Thus, selected markers can be appropriate candidates for personalized treatment of BC patients.