PIK3CA and breast cancer: Compared to pan-PI3K inhibitors [such as Buparlisib and Pictilisib (63)], frequently added in ET or paclitaxel treatment for advanced BC patients, isoform-specific PI3K inhibitors [such as Alpelisib and Taselisib (63)] were generally used according to specific mutated genes in PI3K-AKT pathway.