To evaluate the imprint that the HLA-B −21M/T genotype might have on antitumor effectors, the repertoire of NK and T lymphocytes and the expression of activating (CD226 and CD16) and inhibitory (TIGIT and NKG2A) receptors in NK cells were evaluated in the peripheral blood of 268 BC patients at diagnosis (Figure 5). This evidence concerns the gene TIGIT and breast cancer.