Obesity and gastrointestinal cancer

Background: There is emerging evidence of a strong association between obesity and gastrointestinal cancer. This review summarizes the evidence from an epidemiological and pathophysiological perspective. Methods: Relevant medical literature was identified from searches of PubMed and references cited in appropriate articles were identified. Selection of articles was based on peer review, journal and relevance. Results: Numerous epidemiological studies consistently identified an increased risk of developing oesophageal adenocarcinoma and colorectal carcinoma in the obese. The association between obesity and other gastrointestinal malignancies was less robust. Sex seems important with respect to cancer risk. Adipose tissue, particularly viscerally located fat, is metabolically active and exerts systemic endocrine effects. Putative pathophysiological mechanisms linking obesity and carcinogenesis include the insulin-like growth factor axis, adipocytokines and sex steroids. Conclusion: A better understanding of the mechanisms that link obesity and cancer may uncover targets for intervention. Tackling obesity may result in a reduction in the incidence in addition to mortality of certain cancers in future.