Based on the results of cluster analysis or potential significance for BC (e.g., [27, 28]), we selected ACVR2A, CCNDs, CCNE1, CDC25A, CDK6, CDKN1B, GHR, CHEK1, IGF1R, IRS1, MAPK1, NCOR, PIK3CA, PIK3CB, RARB, SMAD3, SMAD7, and WEE1 for further determination in tumor samples. This evidence concerns the gene PIK3CA and breast cancer.