PIK3CA and neoplasm: For example: Heterogeneous activation states of HER2 signaling: Although HER2 overexpression typically promotes glycolysis via the PI3K/AKT/mTOR axis, compensatory metabolic changes may occur in tumors harboring PTEN loss or PIK3CA mutations, thereby attenuating direct correlations between SUVmax and HER2 status (23).SUVmax reflects only the peak metabolic intensity within a lesion, whereas HER2-induced metabolic reprogramming may manifest more robustly as changes in total metabolic tumor volume (MTV) or total lesion glycolysis (TLG) (24).