Heart Drugs May Reduce Cancer Risk
May 17–Researchers across the country are looking at whether cholesterol-lowering drugs taken by more than 25 million Americans might have an unexpected benefit: protection against a wide variety of cancers.
Although the results from a growing number of preliminary studies on statins are lifting hopes for a broad-spectrum drug to prevent cancer, researchers warn against over-optimism, saying more research is needed. It’s much too early for people to ask doctors for statins as a safeguard against cancer, they warn.
The existing research, though promising, is not considered conclusive because it is based on reviewing historical data to check for connections between the drugs people take and their subsequent health status. Academic institutions and drug companies are reportedly gearing up to conduct controlled clinical trials, which would directly test whether statins reduce the risk of cancer by giving the drugs to some subjects and not to others.
Statins are the most commonly prescribed class of medications in the U.S. and include Lipitor, Zocor, Pravachol, Mevacor, Lescol, Baycol, Crestor and Advicor.
On Monday, a Louisiana researcher reported at a Chicago medical conference that a retrospective study of nearly half a million veterans showed statins were linked to a 59 percent reduction in pancreatic cancer and a 56 percent reduction in esophageal cancer, two of the deadliest cancers.
Dr. Vikas Khurana, of the Overton Brooks VA Medical Center in Shreveport, presented similar findings Saturday to the American Society for Clinical Oncology in Orlando suggesting that statins also appeared to reduce the risk of breast, lung and prostate cancers by 50 percent or more.
“This protective effect is not proven, but at the same time it’s a very exciting finding,” said Khurana, who was in Chicago for the Digestive Disease Week meeting in McCormick Place, the largest gathering of experts in the fields of gastroenterology, hepatology, endoscopy and gastrointestinal surgery. “Statins are looking very promising as a protective effect in cancer across the board.”
Khurana, also an assistant professor of medicine at Louisiana State University, examined the veterans’ past intake of medications, including statins, and their subsequent risk of developing cancer.
Other researchers have found similar protective effects. Jackilen Shannon of the Oregon Health and Science University reported last year that statins appeared to lower the risk of prostate cancer by 65 percent in a study of more than 300 men.
Jane Cauley of the University of Pittsburgh looked at the long-term survival statistics of Scandinavians taking the statin Zocor and found that they had a lower risk of dying of cancer.
And at last year’s ASCO meeting, Dr. Stephen Gruber of the University of Michigan reported that statins reduced the risk of developing colorectal cancer by 51 percent. (That area of study is less clear, however, because some studies have suggested statins may actually promote colon cancer.)
As promising as such findings are, scientists caution that they only represent an association and do not prove that statins actually protect against cancer.
“It’s way too early to start putting people on statins as a cancer preventive because we don’t really know exactly what we’re seeing,” Shannon said.
“What we really need now are some strong animal studies to clarify what is the mechanism that could be functioning here,” she said. “Then some good clinical trials, which are going to be a little hard to do right now because so many people are on statins and you can’t take them off.”
Nevertheless, Shannon said her institution is planning to conduct such a trial.
If the drugs do have a protective effect, the mechanism of action is unclear. But Khurana and others suspect statins may stymie cancer by allowing diseased cells to die off.
Normally a genetic signal tells a cell to die when it is damaged beyond repair. Many cancers escape that process by turning off the signal, allowing cancerous cells to keep dividing out of control.
Statins block an enzyme that is needed by the liver to make HDL, the type of cholesterol linked to heart disease. Khurana said animal studies provide some evidence that those same chemical steps may also promote programmed cell death.
“Statins appear to work in all these different cancers, so it suggests there’s a step in these cancers … that we may want to focus on not only with this drug but with other targets,” said Dr. John Johanson of the University of Illinois Medical School in Rockford, who moderated Monday’s statins session.
“We need to start looking at these drugs more prospectively. The bottom line is that you’ve got to test it on people to see if it works.”
Pancreatic cancer affects 27,000 Americans annually, and their death rate is near 100 percent within a year after diagnosis. Esophageal cancer, which affects 14,520 Americans each year, is nearly as deadly.
Although the results of the VA studies need to be replicated in clinical trials, they nevertheless represent an important step, said Dr. David Rubin, a University of Chicago gastroenterologist.
He said he was encouraged that known risks for the two cancers were supported by Khurana’s data. The studies found that diabetes and older age are linked to a risk for pancreatic cancer and that reflux or heartburn and older age are associated with esophageal cancer.
“By supporting what’s already known, it means that the studies must be on the right track,” Rubin said.
Prescribing statins long term as cancer preventatives must await further careful research because the drugs have some rare but serious side effects, he said, including liver injury and muscle damage.
“We’re a lot closer to having a chemopreventive benefit from statins but more work still needs to be done,” Khurana said. “All our study is doing is moving one step closer to that goal.”
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