PIK3CA and breast cancer: To our knowledge, there is not many studies about PIK3CA gene expression in breast cancer, most studies focused on PIK3CA mutations in breast cancer. PIK3CA expression data in the current study similar to data in the Palimaru et al., (2013) study that showed significantly higher PIK3CA expression in breast carcinoma than in normal breast tissue (p=2x10-11), PIK3CA expression was increased in breast carcinoma in 76% of patients (114/149) whereas in our study the PIK3CA expression was increased in breast carcinoma in 96% of patients (47/50).