The presence of CD8 + T cells in breast cancer is associated with a significant reduction in the relative risk of death from disease.[29] Moreover, CD4+ follicular helper T cell infiltration could predict the prognosis of breast cancer patients.[30] In breast cancer, high density of tumor associated macrophages could predict poor survival rates of patients.[31] Therefore, STAT5B may play a significant role in tumor immune escape, and STAT5B may act as the potential biomarker for immunotherapy in breast cancer. This evidence concerns the gene CD8A and breast cancer.