Excess body weight, a condition leading to insulin resistance and hyperinsulinemia, is a recognized risk factor for postmenopausal breast cancer.1–3 Although the association between body weight and breast cancer is mediated in part by higher levels of estrogen in overweight women, insulin levels seems to have a larger mediating role.4 Recent results show that high levels of insulin levels rather than adiposity is the relevant risk factor in relation to breast cancer risk. Here, INS is linked to hyperinsulinism.