LEP and breast cancer: Elevated body mass index is an important modifiable risk factor for breast cancer.1 With the discovery of adipose tissue as a functioning endocrine organ, much attention has focused on a putative role of adipokines – cytokines and hormones released by adipose tissue – as molecular mediators linking excess adiposity to breast cancer.2, 3, 4 Two adipokines in particular – leptin and adiponectin – have been strongly implicated in breast cancer aetiology.