PIK3CA and breast cancer: The PIK3CA hotspots (H1047R and E545K) were detected in 5 out of 14 samples from the breast cancer cohort, where beyond being described as an independent negative prognostic factor related to increased tumor aggressiveness, it is suggested to condition resistance to fulvestrant and identifies candidates for alpelisib plus fulvestrant therapy in HR+ and HER2- breast cancers (TI, PII, RII) [3,4,5,6,7,8].