A combination of aspirin and cholesterol-lowering drugs, already used by millions of Americans to keep their hearts healthy, may also significantly lower their risk of colon cancer.
New research presented Sunday suggests that these two ubiquitous medicines appear to offer a potent -- if unintended -- shield against a disease that kills about 48,000 people a year in the U.S.
Data from both human and animal studies suggest that together they may eliminate cells in the earliest stages of cancer before they grow into full-blown malignancy.
The work is based on a new analysis of the powerful class of cholesterol-lowering drugs known as statins. The research, conducted by doctors from St. Luke's-Roosevelt Hospital Center in New York City, was released at the annual scientific meeting of the American Association for Cancer Research.
"This is a wonderful example of drugs that are already available that may have an entirely different and important use," said Dr. Frank Rauscher of the Wistar Institute in Philadelphia.
Protective effects of aspirin and similar anti-inflammatory medicines against colon cancer are already suspected from earlier studies. But the possible role of the statin drugs has been much less clear.
Doctors often prescribe aspirin and statins at the same time to prevent heart disease. Statins lower high cholesterol levels that clog the heart arteries, while aspirin makes the blood less likely to form clots that get stuck in tortuously narrowed arteries.
The new work suggests that the same drugs prevent colon cancer by entirely different mechanisms. Although the precise actions are still murky, scientists theorize that they stop cells in the earliest stages of cancer from dividing and induce them to kill themselves off.
No human studies have been set up specifically to test these theories. However, data are available from several large studies on heart patients.
Dr. Banke Agarwal and colleagues examined the results of three of these studies involving more then 15,000 patients. The studies were designed to test how well Mevacor and other statins ward off heart attacks.
Agarwal said the studies suggest that the statins protect against colon cancer, but only when combined with aspirin. In one of the studies, nearly all of the volunteers took aspirin. Those also getting a statin had a 43 percent reduction in colon cancer. However, in another of the studies, only 17 percent took aspirin, and there was no cancer reduction among patients receiving a statin drug.
"On their own, statins may not decrease colon cancer. They only increase the effect of aspirin against cancer," said Agarwal.
To check this idea, the researchers tested Mevacor and an aspirin-like drug called sulindac on rats at risk of developing pre-cancerous colon growths. They found that Mevacor reduced these growths by 12 percent, while sulindac reduced them by 15 percent. But together they reduced the growths by 28 percent.
Agarwl said that while the results are promising, more research is necessary before doctors prescribe these drugs solely to prevent colon cancer.
Written By Daniel Q. Haney