In dichotomized analysis, using the 75% levels of p16INK4a mRNA expression in controls as the cutoff point (4.76), those with higher p16INK4a mRNA expression had 1.81-fold increased risk of breast cancer (OR = 1.81; 95%CI: 1.29, 2.45; p < 0.001). This evidence concerns the gene CDKN2A and breast carcinoma.