Because of the importance of Wnt/β-catenin signaling in breast and ovarian cancer, TCF7L2's critical role in combining with β-catenin, clear associations of rs12255372 with non-cancer phenotypes, and suggestive evidence of association with cancer phenotypes, we hypothesized that genotypes at this SNP may be associated with risk of breast and/or ovarian cancer. Here, TCF7L2 is linked to cancer.