Obesity and cancer: Epidemiological evidence

Obesity, excessive body fat, is often defined by the body mass index (BMI, kg/m²) in observational studies. A body of evidence showed that obesity in mid-life increases the risk of cancers, particularly those in esophagus (adenocarcinoma), gastric cardia, liver, gallbladder, pancreas, colon and rectum, kidney, thyroid, breast (postmenopausal), endometrium, and ovary and multiple myeloma. Emerging evidence also suggests that body fatness at adolescence and early adulthood is associated with a higher risk of cancer in later life, particularly those known to be associated with obesity in late adulthood. Several biological mechanisms explain the link between obesity and cancer.