Long-term use of the drugs may even slightly raise the risk of precancerous colon growths in high-risk people, researchers report.
A number of studies have suggested that statins may protect against a variety of cancers, including that of the prostate. And research in the test tube and mice suggests that statins suppress the growth of colon tumors.
With the new findings, "we feel very confident that statins don't prevent adenomas," or precancerous colon growths, says Monica Bertagnolli, MD, of Harvard Medical School.
Analyzing the Data
The researchers analyzed data from an earlier study looking at whether the painkiller Celebrex could be used to prevent colon cancer. The trial included 2,035 people who were at high risk of colon cancer because they had had adenomas removed; 679 received placebo and the rest received one of two doses of Celebrex.
Based on that and a second study with similar findings, Celebrex is not used to prevent colon cancer, although it is still used to treat arthritis.
As part of that study, researchers collected additional data on patients that they thought might prove useful in predicting the development of new adenomas, Bertagnolli says. Among the questions patients were asked was whether they took statins and if so, for how long.
Statins and Colon Cancer
The new analysis involved only the 679 people who received a placebo in the original study. "Celebrex has a beneficial effect that would impact the results," Bertagnolli explains.
About 36% of the people in the placebo group reported taking statins.
After taking into account other colon cancer risk factors such as age and sex, the results showed that people who took statins at any time over a five-year period were no less likely to develop adenomas than those who didn't.
People who took statins for more than three years, however, had 39% higher odds of developing adenomas than those who didn't take statins.
Louis M. Weiner, MD, director of the Georgetown Lombardi Comprehensive Cancer Center in Washington, D.C., tells WebMD that people on statins should stay on statins.
"This is a small, preliminary, hypothesis-generating study," he says.
Also, only people already at high risk of colon cancer were involved, so the question of whether statins can help prevent colon cancer in the general population is still unanswered, he says.
The best way to avoid colon cancer is to follow national screening guidelines, such as having a colonoscopy beginning at age 50, or earlier if you have a family history or other risk factors, Weiner says.