Obesity

Obesity is one of the clearer indirect contributors to cancer risk. NCI and CDC link excess body weight with increased risk for several cancers, including endometrial, breast after menopause, colorectal, kidney, liver, pancreatic, gallbladder, esophageal adenocarcinoma, and others. Mechanisms include chronic low-grade inflammation, higher insulin and insulin-like growth factor signaling, altered sex hormone levels, adipose tissue signaling, immune changes, and fatty liver/metabolic dysfunction. Obesity does not act like a single chemical carcinogen; it changes the internal environment in ways that can favor cancer development and progression.