Insulinemia and the risk of breast cancer and its relapse.

A fairly large body of evidence has shown that insulin is a tumour-promoting agent, especially for breast cancer. High circulating and microenvironmental levels of insulin may directly increase the risk of breast cancer via the activation of cognate receptors expressed on normal and cancer cells and indirectly be associated with other known metabolic risk factors of cancer that usually are present in conjunction with the hyperinsulinic state. The focus of this review is to analyse and discuss available data in the literature on the possible causative/prognostic role of insulin resistance/hyperinsulinemia in breast cancer development and progression.