Despite the counterintuitive findings concerning their prognosticsignificance, active investigation of PI3K pathway blockade is currently ongoing andstill could prove to be a curative strategy for PIK3CA mutant breast cancers.Prospective clinical trials selecting patients on the basis of PIK3CA mutationsare currently recruiting (Table 2), but upfrontstratification will be required in order to ensure enough power is seen in thePIK3CA mutant subgroup. Here, PIK3CB is linked to breast cancer.