Link of obesity and gastrointestinal cancer: crossroad of inflammation and oxidative stress

Abstract

Obesity incidence has reached pandemic levels, and is accompanied by high incidence and poor prognosis of various types of cancers including gastrointestinal ones. Underlying mechanisms include elevated levels of insulin, IGF-I, and altered adipokine concentration, mainly towards leptin and adiponectin levels. However, it is not yet thoroughly understood. It is now widely known that obesity is associated with chronic low-grade inflammation, characteristic of altered immune cell infiltration in adipose tissue, and changed inflammatory cytokines and chemokines: tumor necrosis factor alpha (TNF-a), IL-6, and the chemoattractant monocyte chemoattractant protein 1 (MCP-1) and others, all together eventually promoting caner pathogenesis. Moreover, accumulating reports have shown that excess adipose tissue in obese individuals resulted in elevated levels of systematic oxidative stress, another way of promoting cancer development and progression. In general, altered immunological milieu and oxidative stress in obesity are important determinants for tumorigenesis