TUESDAY, June 8, 2004 (HealthDayNews) -- Can the popular cholesterol-lowering drugs called statins perform double duty as anti-cancer treatments?
New research suggests they may help to lower the risk of colon cancer. This finding follows previous research that the drugs may protect against a variety of cancers, including breast tumors.
But experts and the study authors alike urge caution when interpreting the results.
In a recent presentation at the American Society of Clinical Oncology annual meeting in New Orleans, researchers reported that people who took statins for five or more years appeared to cut their risk of colon cancer in half.
"I think we have to be very careful about overinterpreting data from observational studies because we've been burned before," said study senior author Dr. Stephen Gruber, an associate professor of internal medicine, epidemiology and human genetics at the University of Michigan Cancer Center. "On the other hand, the weight of evidence suggests that this is a very interesting class of drugs to explore further."
Earlier research showed that women who took statins for five or more years reduced their risk of developing breast cancer by up to 30 percent. And a Dutch study recently found a reduced overall risk of cancer among people taking this class of drugs.
Statins, which were approved by the U.S. Food and Drug Administration in 1987, are taken by millions of people to prevent heart disease. Dr. Donald A. Smith, director of lipids and metabolism at Mount Sinai Medical Center in New York City, said statins can result in a 25 percent to 45 percent reduction in the risk of stroke, heart attacks and deaths from heart attacks by keeping cholesterol levels within safe levels.
The new study is the first to look specifically at statins and colorectal cancer.
The researchers looked at data collected in northern Israel on 1,708 people with colon cancer and 1,737 people without the disease. The reduction in relative risk was 50 percent. And while absolute risk reduction is more difficult to gauge from a study such as this one, Gruber estimated statins would reduce the lifetime risk of developing colorectal cancer from about 3 percent to about 6 percent in a person of average risk.
However, there are methodological problems with an observational study, in which people are interviewed about their use of medications, rather than monitored by doctors.
"You have to be extraordinarily careful," Smith said. "There's a bias inherent in these case controls. The benefit of these studies is that they're so easy to do and they're so cheap. The problem is you can get really false results. Although these are interesting as hypothesis-generating studies, they don't prove a thing."
Smith pointed to the example of estrogen therapy for heart disease. Observational studies had suggested hormone replacement therapy might protect against this disease, but when the Women's Health Initiative was conducted, the opposite was found to be true.
But the authors of the new study think the findings may be more than just a fluke. For one thing, statins appear to turn off cancer genes and reduce inflammation within cells, Gruber said. Also, the data appears to be specific to statins and not to other cholesterol-lowering drugs.
Gruber is in the process of planning clinical trials to see if statins do indeed have a preventative effect on cancer. In the meantime, though, he doesn't recommend that healthy people start taking statins to ward off cancer.
"Based on the fact that this is an observational study and not a clinical trial, I would recommend that healthy people should not be taking statins for this reason," he said. "This should not change the way statins are used because this indication is not FDA- approved."
The National Cancer Institute has more on colorectal cancer.