Evidence continues to mount that cholesterol-lowering drugs called statins can reduce the risk of a variety of cancers. New research shows that the popular statin drugs may slash a person's chance of developing breast, prostate, and lung tumors in half.

Three new studies show that "statins prevent healthy cells from transforming into cancerous cells," says researcher Ruby Kochhar, MD, a medical oncologist at the Naval Medical Center in Portsmouth, Va. "There was a protective effect in every type of cancer studied."

The new studies were presented at the annual meeting of the American Society of Clinical Oncology (ASCO).

Statins are one of the most widely prescribed drugs used in the U.S. to treat high cholesterol. They include medications such as Lescol, Lipitor, Mevacor, Pravachol, and Zocor and work by blocking the body's ability to produce cholesterol.

Statins Reduce Breast, Lung, Prostate Risk

In the studies presented, researchers collected health information on more than 1.4 million men and women from the Veterans Administration. The studies all took into account risk factors for the type of cancer being studied, including age, smoking, and alcohol use.

For the breast cancer analysis, they compared statin use among 556 female veterans diagnosed with breast cancer and 39,865 women of similar ages without the disease.

They show that statin use was associated with half the risk of breast cancer.

During a six-year period, women who used statins reduced their risk of breast cancer by more than half (51 percent) compared with nonusers, says researcher Vikas Khurana, MD, assistant professor of medicine at Louisiana State University Health Sciences Center in Shreveport.

A second analysis shows a reduction in the risk of lung cancer. Statin users were 48 percent less likely to develop lung cancer than nonusers, Khurana tells WebMD. This study included nearly 450,000 people, 10 percent of whom were women.

A third analysis shows that statin use reduces the rate of prostate cancer by 54 percent, says researcher Rakesh Singal, MD, associate professor of medicine at the University of Miami.

The longer the men took the cholesterol-lowering drugs, the greater the benefit, he tells WebMD.

Men who took them for a year or less had almost no protection, while those who took them for more than four years saw their risk of prostate cancer drop by nearly 90 percent.

Questions Remain About Statins' Cancer-Fighting Ability

The researchers did not look at whether the type or dose of statins affected the results, although they plan to do so in future studies.

Also, the information about statins is based on prescription records, Signal says, so it's not possible to say whether the men who were prescribed the drugs actually took them properly.

Too Soon to Recommend Statins

The studies follow on the heels of other research showing that statin use is associated with a reduced risk of a variety of cancers, including melanoma. Just last month, researchers reported that the drugs cut the risk of advanced prostate cancer in half.

Paul Bunn, MD, director of the University of Colorado Comprehensive Cancer Center in Denver and a past president of ASCO, says it makes sense that statins would have a broad anticancer effect.

"The drugs work by blocking an enzyme involved in cholesterol production," he says. "It's a complicated process, but basically what happens is that the drugs [inactivate] a series of proteins involved in cholesterol production. And some of these same proteins are used by cells to promote tumor growth," Bunn tells WebMD.

While it's still too soon to recommend that people at high risk for cancer start taking statins for their antitumor properties, the new research may give statins an edge over other cholesterol-lowering drugs, researchers say.

"Right now, if you need to be prescribed a drug for cholesterol lowering, many studies suggest you would be better off choosing a statin for its cancer-preventive effect," Khurana says. "But we're not yet ready to prescribe them to [people without high cholesterol]."

Bunn agrees. "People, including myself, who are taking statins might have a lower risk of some cancers, be the colon, prostate, or whatever," he says. But until large, well-designed studies offer firm proof that they prevent cancer, he urges healthy people to refrain from asking their doctors for the drugs.

By Charlene Laino, reviewed by Brunilda Nazario, MD

SOURCES: 41st Annual Meeting of the American Society of Clinical Oncology, Orlando, Fla., May 13-17, 2005. Ruby Kochhar, MD, medical oncologist, Naval Medical Center, Portsmouth, Va. Vikas Khurana, MD, assistant professor of medicine, Louisiana State University Health Sciences Center, Shreveport. Rakesh Singal, MD, associate professor of medicine, University of Miami, Fla. Paul Bunn, MD, director, University of Colorado Comprehensive Cancer Center, Denver; past president, American Society of Clinical Oncology.