Higher weight and stores of body fat are linked to poorer survival and prognosis among patients with breast cancer (Petrelli et al, 2002; Borugian et al, 2003), most likely mediated by the associated higher levels of oestrogen (Leenen et al, 1994), insulin (Weinstock et al, 1998) and bioavailable insulin-like growth factor-1 (IGF-1) (Nam et al, 1997). The gene discussed is INS; the disease is breast cancer.