PIK3CA and breast cancer: The aim of this study was to assess possible associations between the efficacy of neoadjuvant anti-HER2 treatment in early HER2-positive BC patients and the presence of 28 SNPs affecting the 17 genes or DNA regions: PON1, CAT, GSTP1, FCGR3, ATM, PIK3CA, HER3, BARD1, LDB2, BRINP1, chr6 intergenic region, RAB22A, TRPC6, LINC01060, EGFR, ABCB1, and HER2.