The biological mechanisms by which PA may decrease prostate cancer risk are unknown, but PA may affect certain hormones hypothesised to be associated with prostate carcinogenesis, including insulin resistance (Goodyear and Kahn, 1998), adiponectin levels (Kelesidis et al, 2006; Bluher et al, 2007), insulin-like growth factors (Chan et al, 1998) and testosterone (Eaton et al, 1999). The gene discussed is ADIPOQ; the disease is prostate cancer.