In primary breast cancer tissues, the mean methylation level was 1.40 ± 0.90% for the NFKB1 gene and 1.49 ± 0.50% for the RELA gene, while that of two genes in normal mammary tissues was 1.51 ± 0.66% and 1.60 ± 0.19%, respectively. This evidence concerns the gene NFKB1 and breast cancer.