Lowering cholesterol as much as possible may reduce the risk of heart disease, but with a price: Taking it too low could raise the risk of cancer, U.S. researchers reported Tuesday.
Patients who took statin drugs to lower their cholesterol had a slightly higher risk of cancer, although the study did not show that the statin drugs themselves caused the cancer.
The researchers found one extra case of cancer per 1,000 patients with the lowest levels of LDL — low-density lipoprotein or so-called bad cholesterol — when compared to patients with higher LDL levels.
Dr. Richard Karas of Tufts University School of Medicine in Boston and colleagues did not look directly at patients for their study, published in the Journal of the American College of Cardiology.
Instead, they did what is known as a meta-analysis, looking at the records of 41,173 patients in 23 different trials of statins.
"The demonstrated benefits of statins in lowering the risk of heart disease remain clear; however, certain aspects of lowering LDL with statins remain controversial and merit further research," Karas said in a statement.
Risks and benefifts
Statins are the world's top-selling drugs, pulling in billions of dollars for their makers. They lower the risk of heart attack and stroke, and evidence also suggests unexpected benefits, such as a lowered risk of death from influenza, pneumonia and the effects of smoking.
Experts believe some of the beneficial effects may come from the drugs' effects on inflammation in the body.
But lowering cholesterol too far can be harmful, and people with extra-low cholesterol may have a higher risk of Parkinson's disease. Statin drugs can also damage the liver and muscles.
The Karas study adds cancer to those concerns.
Karas and colleagues said they examined the records of patients treated with popular statins, including Pfizer Inc.'s Lipitor and Merck & Co. Inc.'s Zocor, which is now off patent.
They did not include data from recently launched statins such as AstraZeneca Plc's Crestor and Merck/Schering-Plough Corp.'s Vytorin.
Cancer risk may be tied to simply living longer
Dr. John LaRosa of the State University of New York Downstate Medical Center in Brooklyn, who wrote an accompanying commentary in the journal, said the new research needed to be seen in perspective.
"These current findings provide insufficient evidence that there is any problem with LDL lowering that outweighs its significant benefits on vascular disease," he wrote.
One possibility is that the higher cancer risk in patients with low LDL reflects the fact they live longer and are therefore more likely to develop cancer, LaRosa said.
Andrew Baum, an analyst with Morgan Stanley in London, said concerns over statin safety had waxed and waned over the past 10 years, and few physicians were likely to change prescribing practice following the news.