Metformin has been identified as a potential breast-specific aromatase inhibitor.171,172 Interestingly, the adipokine adiponectin and the hunger hormone ghrelin have also been shown to suppress aromatase expression in a promoter-specific manner, which may help to explain the association between low levels of adiponectin and breast cancer growth in the setting of obesity.159,173,174 It remains to be determined whether these results can be leveraged to improve treatment of obesity-related breast cancer. This evidence concerns the gene CYP19A1 and breast cancer.