Multifaceted breast cancer. The molecular connection with obesity

Obesity is characterized by a disruption in energy balance regulation that results in an excess accumulation of body fat. Its increasing prevalence poses a major public health concern because it is a risk factor for a host of additional chronic conditions, including type 2 diabetes, hypertension, and cardiovascular disease. Obesity is increasingly recognized as a growing cause of cancer risk. In particular excessive adipose expansion during obesity causes adipose dysfunction and inflammation that can regulate tumor growth. In obesity, dysregulated systemic metabolism and inflammation induce hyperinsulinemia, hyperglycemia, dyslipidemia, and enhance sex hormone production with increased secretion of proinflammatory adipokine that impact breast cancer development and progression. This review describes how adipose inflammation that characterizes obesity is responsible of microenvironment to promote cancer, and discuss how steroid hormones, that are essential for the maintenance of the normal development, growth and differentiation of the cells, influence the induction and progression of breast cancer.