Breast cancer patients showed a non-significant higher methylation frequency for SPAG6 (mean of 6.6% in benign controls versus 8.4% in breast cancer cases, p = 0.2536), PER1 (2.6% versus 4.8%, p = 0.5792), NKX2-6 (1.3% versus 2.9%, p = 0.1898) and ITIH5 (6.8% versus 5.9%, p = 0.9343). This evidence concerns the gene PER1 and breast cancer.