PIK3CA and breast carcinoma: Within those subtypes, PIK3CA mutations were only associated with temsirolimus sensitivity in tumor cells from the aerodigestive tract (P = 0.014; one-tailed t-test) and cervical tumor cell lines (P = 0.023), but no such association could be seen for PIK3CA mutation status in breast cancer (P = 0.411), and an opposite effect was observed in endometrial cancer (P = 0.053).