In this study, we carried out and quantified CD56 and MICA immunostaining in human breast tissues to investigate if and how CD56+ NK cell and NK cell ligand densities vary in nonmalignant breast lobules (1) between women who develop breast cancer and women who remain cancer-free, (2) according to age, (3) according to lobular involution, a histologic risk factor for cancer [21], and (4) according to fibrocystic status/epithelial proliferation, another established risk factor [22, 23]. This evidence concerns the gene MICA and breast carcinoma.