PIK3CA and breast cancer: In the adjusted analysis of three [51, 100, 106] and two studies [51, 100] for PIK3CA and TP53 genes, respectively, breast cancer patients harbouring mutation in the PIK3CA gene was associated with worse response (OR 0.64; 95% CI 0.42-0.98; p=0.04; Supplementary Figure 7.2B in Additional file 7) while TP53 gene was not associated with pCR outcome (OR 1.34; 95% CI 0.59–3.05; p=0.49; Supplementary Figure 7.2B in Additional file 7).