The efficacy of PI3K inhibitors is thought to be driven, at least in part, by inhibiting PI3K-dependent steps of the glycolytic pathway and limiting glucose flux (Juric et al., 2018, 2019), with reduced fluorodeoxyglucose-positron emission tomography (FDG-PET) uptake observed in ER+ve breast cancer patients treated with the PI3K inhibitor alpelisib (Juric et al., 2018). This evidence concerns the gene PIK3CA and breast cancer.