Less is more: caloric restriction and tumor inhibition

Lesley wrote about the importance of lifestyle factors in her blog entry on "What if preventing cancer were really that easy?" We've all heard that a healthy diet is a central ingredient in reducing cancer risk. Researchers at M. D. Anderson Cancer Center are reporting that it isn't just what foods you eat but how much you consume compared with your activity level that can impact tumor formation.

Dietary energy balance is the balance between caloric intake and energy expenditure. Chronically positive energy balance leads to obesity and increased risk of multiple cancer types. I think most of us intuitively understand that we should try to achieve a zero energy balance-- calories in equals energy used. But at least in laboratory mice exposed to a cancer-causing agent, a negative energy balance actually inhibits the formation of tumors (in this study, a type of skin cancer known as papilloma). Reducing the number of calories that the mice were fed by 15% or 30% produced significant tumor inhibition.

The lead author of this study, Tricia Moore, reports that energy balance inhibits two key cell surface receptors (EGF and IGF-1 receptors) that are major controllers of cell growth and proliferation.

It's possible that we may one day see moderate (perhaps short-term) caloric restriction as a "combination-therapy" to be prescribed along with more conventional pharmaceuticals.