The researchers point out that it's easy to know if statins are successfully lowering cholesterol, but their effect on colorectal cancer prevention is not as apparent. That's where a gene test would come in.

"We think we understand the reasons why statins lower the risk of colorectal cancer. It's probably related to the fact that in addition to lowering cholesterol, they also decrease inflammation - and we know inflammation is a very important part of the way in which colon cancers develop. But regardless of whether it's related to cholesterol levels itself or inflammation, it's more important to know who are the right people to use these drugs for," says Gruber, H. Marvin Pollard Professor of Internal Medicine and professor of epidemiology and human genetics at the U-M Medical School and School of Public Health.

Note for patients: Statins are not currently approved by the U.S. Food and Drug Administration for colorectal cancer prevention. No gene test is available for determining statins' effectiveness. Talk to your health care provider for information about lowering your cancer risk.

Colorectal cancer statistics: 146,970 Americans will be diagnosed with colorectal cancer this year and 49,920 will die from the disease, according to the American Cancer Society

Source: University of Michigan Comprehensive Cancer Center