Do Statins Protect Against Cancer?

by National Cancer Institute

Statistical Study Fails to Find Evidence That Statins Protect Against Cancer

Summary

Researchers analyzed data from multiple clinical trials in which thousands of patients took drugs called statins to reduce their risk of heart disease and found no evidence that the drugs reduced the risk of cancer. The analysis is not the final word on the subject, however, as evidence from other kinds of studies suggests that statins may offer some protection against cancer.

Source

Journal of the American Medical Association, January 4, 2006 (see the journal abstract).

Background

Millions of Americans take statins to lower their cholesterol levels and their risk of heart diseases. These drugs work by blocking an enzyme called HMG-CoA reductase, which the body needs to make cholesterol.

Animal studies and observation of people who take statins have suggested that these drugs might also reduce the risk of some cancers. Researchers have found that statins inhibit certain processes in cells that may help tumors to form, grow, and spread. Previous retrospective studies have suggested that statins might reduce the risk of cancers of the colon, breast, lung, and prostate.

The Study

Researchers searched the published medical literature for studies of statin use in which information on cancer diagnoses and deaths was also reported. They identified 26 randomized, controlled trials that enrolled at least 100 patients and followed the patients for at least one year.

Using a statistical technique known as meta-analysis, they pooled and summarized the information from these studies on cancer diagnoses and deaths. They evaluated the effect of all five statin drugs available in the United States on six types of cancer (breast, colon, and prostate cancer; respiratory and gastrointestinal cancers; and melanoma).

The study's senior author is C. Michael White, Pharm.D., of the University of Connecticut School of Pharmacy in Storrs.

Results

The 26 clinical trials included in the meta-analysis enrolled more than 86,000 patients. They recorded more than 6,600 cancer diagnoses and more than 2,400 cancer deaths among those patients.

The researchers found no statistically significant differences in the number of cancer diagnoses or deaths between patients who were randomly assigned to take statins and those who were not. Their findings were the same for each of the six types of cancer they looked at.

Limitations

This study draws on data from clinical trials that were designed to determine statins' effects on heart diseases, says the National Cancer Institute's (NCI's) Ernie Hawk, M.D., M.P.H. Because the drugs' effects on cancer was not the trials' primary focus, "they may have had limited ability to detect a difference in cancer incidence associated with statin use," Hawk explains.

"In addition, because cancer often takes many years to develop, none of these trials may have followed patients for long enough to find an effect of statins on cancer incidence if such an effect exists," he adds.

Comments

"This analysis does not support the premise that statins may prevent cancer, but neither does it prove the converse - that statins have no preventive effects on cancer," says Hawk. "The question remains unresolved."

An NCI-sponsored phase II trial that is about to get under way may shed more light on this question. This trial will enroll patients who are at increased risk for colorectal cancer and who are known to have clusters of abnormal cells in the lining of the colon and rectum. These abnormal cells are the earliest stage at which colorectal cancer risk is detectable with existing technology.

The trial will test three drugs - including the statin atorvastatin (Lipitor®) - to see whether they can effectively prevent these clusters of abnormal cells from progressing toward colorectal tumors. Paul Limburg, M.D., a researcher in gastroenterology at the Mayo Clinic in Rochester, Minnesota, is the principal investigator for this multicenter study.

About the Author

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