Obesity and gastrointestinal neoplasia—what are the biologic mechanisms?

A recent review in Gastroenterology, by Alemán and colleagues, provides a comprehensive outline of mechanisms through which obesity may increase the risk of gastrointestinal (GI) cancers. While very plausible general concepts, such as the involvements of inflammation, growth hormone signaling, or alterations of the microbiota in cancer development are presented, direct evidence for the relative causal contributions of various types of mechanism still appears limited. Despite the increasing knowledge about the molecular basis of the obesity-cancer connection, the translation of basic research findings into cancer prevention and treatment remains challenging.