By Sarah L. Zielinski
Cholesterol-Lowering Drugs for Cancer
Statin studies cast doubt on earlier findings of reduced cancer risk
By Sarah L. Zielinski
Last summer, a handful of studies generated excitement over the possibility that widely used cholesterol-lowering drugs, such as Lipitor (atorvastatin), Crestor (rosuvastatin) and Zocor (simvastatin), may reduce the risk of colorectal, breast, lung and prostate cancers. However, further studies now suggest that the drugs, called statins, have no such effect.
The earlier studies were all retrospective, meaning that researchers looked back at the medical records of healthy people and of cancer patients to study their statin use. Determining if statins do indeed affect cancer risk requires a large, prospective randomized clinical trial, says pharmacologist C. Michael White, of the University of Connecticut School of Pharmacy.
Such a trial needs a group of volunteers who are randomly selected to take a statin or a placebo. Doctors then monitor the two groups and compare the number of cancer cases after a certain time period.
This type of research, though, takes a large amount of time and resources. So White and his colleagues decided to examine data from large randomized trials that had tested statins for their ability to lower the risk of coronary events, such as heart attacks, and that also reported data on cancer incidence or death.
They analyzed data from 26 trials—which included nearly 87,000 people—and found no association between statin use and the incidence of or death from any type of cancer. In addition, no single type of statin was associated with cancer incidence or death, they reported in the Jan. 4 Journal of the American Medical Association.
"The tide is kind of turning on statins as an anti-cancer medicine," says White.
However, the results of the study don't rule out that statins may have some kind of anti-cancer effect. Laboratory studies show that this class of drugs can prevent certain cell activity that helps cancer cells grow and spread.
In a study published May 17 in the Journal of the National Cancer Institute, epidemiologist Jane A. Cauley of the University of Pittsburgh and her colleagues examined the effect of statin use in the more than 150,000 women participating in the Women's Health Initiative (see box below).
Although there was no overall benefit from taking statins, there was evidence that a specific class of these drugs that includes Zocor may be associated with reduced breast cancer risk, says Cauley. However, most studies of statins and cancer haven't looked at the type of statin used.
"I don't think we have a clear answer" yet about whether or not statins affect cancer, Cauley says.
THE WOMEN'S HEALTH INITIATIVE
The Women's Health Initiative (WHI) was established by the National Institutes of Health in 1991 to focus on heart disease, osteoporosis, breast cancer and colon cancer. It was planned as a 15-year endeavor that included three main areas: randomized clinical trials, observational studies and community-based strategies for developing healthy behaviors.The study involved 161,808 women ages 50 to 79.
The randomized, controlled clinical trial—the part of the study discussed in the accompanying article—included 68,132 women. The women could enroll in a hormone therapy trial, a vitamin D/calcium trial or a low-fat diet trial (some enrolled in all three trials). Women were followed for seven to eight years.
In February, Women's Health Initiative researchers reported the following:
- Following a low-fat diet does not reduce the risk of breast cancer
- Maintaining a low-fat diet does not reduce the risk of heart disease or stroke
- Taking calcium and vitamin D supplements together does not reduce the risk of colon cancer
- Using calcium and vitamin D supplements together does not reduce the risk of fractures