Previous studies have already found certain kinds of polymorphisms in DNA repair proteins are associated with cancer, such as XRCC3 (Thr241Met), OGG1 (Ser326Cys) and XPD (Lys751Gln) with breast cancer, XRCC2 (R188H G>A), and XRCC3 (T241M C>T) with ovarian cancer, XPC C/A (i11) with sporadic colorectal cancer and so on. The gene discussed is XRCC2; the disease is breast cancer.