Currently, with the rapid development of immune checkpoint inhibitors (ICIs) treatment, such as cytotoxic T-lymphocyte antigen 4 (CTLA-4) and programmed cell death molecule 1 (PD-1)/programmed cell death molecule ligand 1 (PD-L1) inhibitors, ICIs are replacing traditional therapeutic drugs and becoming new first-line and second-line treatment options for BC, marking the huge potential and hope of immunotherapy in BC. This evidence concerns the gene CTLA4 and breast cancer.