PIK3CA and triple-negative breast carcinoma: In particular, PIK3CA activating mutations comprise up to 47% of HR+/HER2– (luminal A), 33% of HR+/HER2+ (luminal B), 39% of HR-/HER2+ (HER2-enriched), and 8–25% of basal-like/triple negative breast cancer subtypes [18,19,20,21,22,23,24,25].