Get the fat out!

Obesity is associated with increased risk of a number of cancers in humans, but the mechanism(s) responsible for these associations have not been established. It is estimated that 68% of adults are overweight or obese and that obesity maybe causative in 4% to 7% of cancers in the United States. Several hypotheses have been put forward to explain the association between obesity and cancer including adipose-directed signaling (e.g., mTOR, AMPK), production of factors (e.g., insulin growth factor 1, fibroblast growth factor 1, and/or chronic inflammation associated with obesity. Huffman and colleagues used surgical methods to determine if visceral fat was causally related to intestinal tumorigenesis in the Apc^1638/N+ mouse in a manner independent of confounding factors such as caloric restriction. They found that caloric restriction could extend survival in both male and female Apc^1638/N+ mice but found that surgical removal of visceral fat was only effective in reducing macroadenomas in females. The results of this study do not identify the specific mechanism of association between visceral fat and intestinal carcinogenesis in female mice but do support the rationale for future cancer prevention trials that evaluate pharmacologic and behavioral strategies to reduce abdominal obesity in humans.