A study be Onay et al. also concluded that 19 individual commonly occurring SNPs associated with 18 key cancer genes XPD, PTEN, GADD45, p27, ESR1, CYP17, GSTM3, MTHFR, IL1a, IL10, IL13, TNFa, G-CSF, CCND1, COMT, BARD1, GSTP1 and MMP1 did not contribute to breast cancer risk (Onay et al. 2006). This evidence concerns the gene ESR1 and breast cancer.