Impact of the tumor microenvironment of breast cancer on prognosis and treatment

According to World Health Organization, breast cancer (BC) ranks first among cancer diseases in women in many developed countries of the world and in the Russian Federation. Over the past 20 years, the incidence of breast cancer in the world has increased and continues to increase. This phenomenon dictates the need for a more in-depth molecular biological, genetic and immunological study of the mechanisms of development and progression of this heterogeneous malignant tumor. Recently, there has been increasing interest in the world not only in the direct causes of tumor development, but also in factors contributing to its progression, such as the cellular microenvironment of the tumor, the composition of which has a great influence on cancer development, treatment and prognosis. In the cellular microenvironment of the tumor, mononuclear cells are assessed, the proportion of which determines the severity and direction of the immune response. Their importance for choosing the priority type of drug therapy and assessing its effectiveness is shown. The article provides current data on subpopulations of T cells (CD8+, CD4+), B cells (CD20+), and natural killer. Their role in the development and progression of breast cancer is discussed depending on their phenotype. Modern research pays attention to a minor subpopulation of T lymphocytes – TCR-Vδ1+ cells. This subpopulation is represented predominantly in tumor tissue and has an immunosuppressive effect on T-effectors. At the present stage, inflammatory cells – macrophages and neutrophils – are of no less interest. Their role in tumor progression is widely debated. It is known that the differentiation of macrophages into M1 or M2 phenotypes is determined by the tumor microenvironment. The predominance of macrophages with protumor activity promotes tumor progression and cancer metastasis. Additionally, macrophages can stimulate the migration of neutrophils, which, in turn, support the metastasis of breast cancer through the production of matrix metalloproteinases. Matrix metalloproteinase 9 has been reported to promote the formation of vascular endothelial growth factor, which explains the protumor properties of neutrophils. In the context of growing tumor immunotherapy, assessment of tumor microenvironmental factors is promising both in relation to monitoring the effectiveness of breast cancer therapy and in relation to the search for potential therapeutic targets. The review systematizes and summarizes information on this issue to date. © 2024, ABV-press Publishing House. All rights reserved.