This study "contributes to accumulating evidence that caloric restriction acts by altering hormone levels rather than by directly starving cancers of energy. In particular, lower levels of insulin are associated with reduced food intake, and this may be protective," said Pollak, who is also an editorial board member for Cancer Prevention Research.

In the editorial Pollak wrote: "there is reason for concern that the 'obesity epidemic' may lead to an increased prevalence of a hormonal profile associated with elevated cancer risk and/or an adverse cancer prognosis. Therefore, in addition to its well-known general health benefits, maintaining an ideal body weight is also important in the specific contexts of cancer prevention and improving the prognosis of cancer patients."

Based on varied findings from clinical trials, Pollak suggested that lifestyle and pharmacologic methods to reduce IGF-1 and insulin deserve ongoing investigations. Cleary agreed, stating that these results may provide interest to more aggressively pursue cancer prevention studies related to calorie restriction.

"Humans frequently regain lost weight discouraging the application of calorie restriction protocols for disease prevention," she said. "We hope these studies will identify biomarkers and/or pathways that could be used in human studies to determine agents that would mimic calorie restriction."

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