PIK3CA and breast cancer: Meanwhile, PIK3CA mutations were more frequently detected from HR+/HER2+, HR−/HER2+ and HR+/HER2− breast cancer and less common in TNBC (P < 0.01), with detection rates of 50.0% (10/20), 44.4% (16/36), 33.0% (30/91), and 21.2% (29/137), respectively (Figure 2).