We would purport from these observations in AI-treated breast cancer (in which estrogen signalling has been dysregulated) that tumour cells have the potential to adapt and utilize bioavailable steroids such as those of adrenal origin: 75 % of breast tumours are positive for AR and so it is of interest to evaluate how these cells adapt to the preponderance of circulating androgens that occurs during prolonged treatment with AI therapy. This evidence concerns the gene AR and breast cancer.