The University of Wisconsin-Madison says there is a correlation between exercise, diet and a lower risk of colorectal cancer.

There have been several studies that suggest exercise and diet are cancer fighters. This new study is unique in that it suggests a "negative energy balance" is an important factor in inhibiting the growth of polyps. Polyps are forerunners of colorectal tumors.

The study was conducted on mice. A negative energy balance was acheived through a combination of exercise and caloric restriction (otherwise known as dieting). More interesting is that the mice exercised voluntarily - one group was given access to a wheel and one wasn't.

The Unversity of Madison-Wisconsin has an extensive blog post discussing the study.