Chapter 25 - Genetic Basis Linking Variants for Diabetes and Obesity with Breast Cancer

Abstract

Obesity is a well-documented risk factor for breast cancer. Several hypotheses were proposed to explain the molecular mechanism through which the obesity contributes to breast cancer risk. Because obesity also increases the risk for metabolic syndrome and diabetes, factors such as insulin-like growth factor-1, adiponectin, adiponectin receptor 1, leptin, leptin receptor, and fat mass and obesity candidate genes were explored in various case-control studies. In these studies, a link between the diabetes- and obesity-associated genes with breast cancer risk were demonstrated. Because adipose tissue contributes to peripheral estrogen synthesis, increased catechol estrogens contribute to the breast cancer risk; xenobiotic genetic polymorphisms were also explored to explain the obesity-mediated breast cancer risk. Further, the obesity was also reported to induce certain epigenetic alterations that predispose to breast cancer risk. In this chapter, we have summarized the different genetic variants that link obesity with diabetes and breast cancer risk.