Tumor-associated Macrophages in Breast Cancer: Potential Therapeutic Strategies and Future Prospects

Abstract

Among women, breast cancer (BC) ranks as one of the most prevalent malignant tumors and is the primary cause of mortality from cancer. Circulating monocytes and embryonic tissue-resident cells give rise to tumor-associated macrophages (TAMs). TAM represents the major immune cell population in the breast tumor microenvironment and are closely associated with BC onset, progression and metastasis. This review highlights that TAM cells are classified into M1 and M2 types, and the two subtypes can be transformed into each other under certain conditions with a high degree of plasticity. TAM can contribute to BC growth by promoting the growth of cancer cells, facilitating tumor immune escape and enhancing cancer drug resistance. In addition, this review emphasized that immune resistance in BC can be overcome by inhibiting TAM recruitment, reprogramming TAM, removing existing TAM and blocking the immunosuppressive function of TAM. In the future, the combination of TAM and immune checkpoint inhibitors will become the mainstream direction for improving the survival cycle of patients with advanced breast cancer.