PIK3CA and breast cancer: By comparing the gene mutation profiles of breast cancer, it was found that the mutations of CBFB, PIK3CA, MAP3K1, and ARID1A in the HER2‐low subgroup were more common, while the mutations in TP53, TERT, GALNT12, CARD11, TRRAP in the HER2‐zero subgroup were more common.27