Obesity as an Important Risk Factor for Certain Types ofCancer (Such as Breast Cancer)Hossain Davoodi*

Cancer is the uncontrolled and unrestricted growth of malignant cells in the body. It is a multifactorial disease which either heredity or environmental factors (such as nutrition, physical inactivity, alcohol, obesity, exposure to sun, environmental pollutants, infections) contribute to the incidence of cancer. In recent years, several lines of research have focused on obesity as a potent risk factor of cancer. Scientific evidence suggests obesity is associated with increased risk for a number of different types of cancer. The evidence is most consistent for endometrial cancer, breast cancer in postmenopausal women, and renal cell cancer. More contradictory results have been reported for colorectal, prostate, and pancreatic cancer. In despite of numerous studies in regard to the link between obesity and cancer, The molecular mechanismsin which obesity increase the risk of cancer have been poorly understood. In this article, the association between obesity and cancer risk and its underlying mechanisms are reviewed.