Obesity and cancer: new evidence continuous update project

The continuous update project: Emerging findings and implications

Alan Jackson

University of Southampton, Southampton, Reino Unido

Introduction/Objectives: In 2007 WCRF/AICR published a comprehensive, systematic review of the world literature which demonstrated that diet, nutrition and physical inactivity cause cancer in specific sites. It was estimated that these factors account for around 25 to 30% of cancer cases. In 2009 a systematic review of the evidence to support policy actions to prevent cancer was published. Since 2007 the database on cancer causation has been maintained with ongoing review for each cancer site, the Continuous Update Project (CUP). The CUP has completed and published updated reviews for cancers of the breast, colon and rectum, pancreas, endometrium, prostate, ovary, liver and gallbladder. A systematic literature review of studies related to breast cancer survivors has been published. The updated reviews largely confirm or strengthen the recommendations for cancer prevention from the 2007 report. WCRF/AICR will present the CUP results on early life exposures for various cancers and will review potential mechanisms underlying such associations, including considerations of mechanisms linked to birth weight, aspects of maturation, and adult height. Development: It has been known for many years that nutritional exposures in early life determine the phenotype at later ages. There is a large, consistent body of evidence that early life events, including fetal and child growth and maturation, are associated with cardiometabolic risk in humans. More recent evidence, as systematically reported in the WCRF /AICR Second Expert Report and the CUP, shows that markers of early life events, growth and maturation are also associated with risk of several cancers. Animal studies indicate plausible mechanisms through which such effects might be mediated in humans. However, the direction of effect is different, with greater growth during early life increasing cancer risk but reducing cardiometabolic risk. It will be particularly important to understand the mechanisms that underlie these different associations in order to determine preferred growth trajectories, safe and effective advice for childcare and public health. Conclusion:There is a growing evidence base that nutrition in early life may have important influences in determining susceptibility to certain cancers in later life. Anthropometric measures such as birth weight, adult height, and the trajectory of growth in childhood are predictive of risk for several cancers common in urbanized societies. Key words: Cancer, cancer prevention, early life exposures.