PIK3CA and breast carcinoma: Among 25 IHC studies included in a meta-analysis of loss of PTEN expression in breast cancer, 10 studies considered any staining PTEN positive, eight studies had a range between 5% and 15% regardless of intensity as the cutoff for PTEN positivity, five used H-scores of 30–100 as the cutoff to include both intensity and extent of staining in the evaluation, and two required moderate or strong staining to any extent to be counted as positive.12 The diversity in criteria for PTEN loss was also reflected in the clinical trials targeting the PI3K pathway.