The result showed that compared with the low-risk group, the infiltrated tumor-killing immune cells in the breast cancer tissues of the high-risk group were significantly reduced, such as CD8+ T cells, γδT cells and activated NK cells, whereas the immune cells promoting tumor proliferation and metastasis, M2 macrophages, were increased (Henning et al., 2018; Hodgins et al., 2019; Sebestyen et al., 2020) (Tariq et al., 2017). The gene discussed is CD8A; the disease is breast cancer.