Dual Functions of T Lymphocytes in Breast Carcinoma: From Immune Protection to Orchestrating Tumor Progression and Metastasis

SIMPLE SUMMARY: New insights into the foundation of cellular and molecular cancer immunology have revealed that immune cells play crucial roles in the development and growth of breast cancer (BC). T-cells are one of the most important cells in the tumor microenvironment and are divided into several subtypes including helper, cytotoxic, and regulatory subsets according to their transcription factors, markers, and functions. This article provides a comprehensive review of contradictory functions of various T-cell subsets in the prognosis and treatment of patients with BC, and crosstalk between tumor cells and T-cells. The literature shows that the role of T-cells in BC immunity depends on a variety of factors, including the tumor type or subtype, the stage of the disease, the localization of the cells in the tumor tissue and the presence of different cells or cytokines. ABSTRACT: Breast cancer (BC) is the most common cancer type in women and the second leading cause of death. Despite recent advances, the mortality rate of BC is still high, highlighting a need to develop new treatment strategies including the modulation of the immune system and immunotherapies. In this regard, understanding the complex function of the involved immune cells and their crosstalk with tumor cells is of great importance. T-cells are recognized as the most important cells in the tumor microenvironment and are divided into several subtypes including helper, cytotoxic, and regulatory T-cells according to their transcription factors, markers, and functions. This article attempts to provide a comprehensive review of the role of T-cell subsets in the prognosis and treatment of patients with BC, and crosstalk between tumor cells and T-cells. The literature overwhelmingly contains controversial findings mainly due to the plasticity of T-cell subsets within the inflammatory conditions and the use of different panels for their phenotyping. However, investigating the role of T-cells in BC immunity depends on a variety of factors including tumor types or subtypes, the stage of the disease, the localization of the cells in the tumor tissue and the presence of different cells or cytokines.