ERBB2 and breast neoplasm: Estimated using the ssGSEA (single sample gene set analysis) method (Barbie et al., 2009), PIK3CA‐mutant breast tumors showed activated AKT, IGF1‐mTOR, and WNT canonical signaling pathways compared to PIK3CA‐wild‐type and HER2‐overexpressing tumors (Fig. 6B).