CCNA2 and breast cancer: The DNA methylation analysis [29,30] also concluded that 11 of the top 10 genes in Table 1, which are CCNA2, CCNB1, TP53, BRCA1, TOP2A, CCND1, AKT1, CREBBP, SMAD4, ESR1, and CENPE, had a higher level of DNA methylation in breast cancer.