Those who take statins to lower their cholesterol run a small increased risk of developing cancer, although the evidence is not yet clear, finds a new study to be published in the Journal of the American College of Cardiology.
The study found that those who achieve very low LDL (low-density lipoprotein, also called "bad" cholesterol) levels after taking statins have an increased cancer risk -- about one additional incident of cancer per 1,000 patients with low LDL levels, compared to patients with higher LDL levels.
But the researchers say the finding, made almost by accident, is no reason for people to stop taking statins, which are sold in Canada under such brand names as Lipitor, Pravachol and Zocor.
"This analysis doesn't implicate the statin in increasing the risk of cancer," said lead author Dr. Richard H. Karas, professor of medicine at Tufts University School of Medicine.
"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."
The researchers evaluated randomized controlled statin trials published before November 2005, looking at 13 treatment arms consisting of 41,173 patients. They had set out to determine how and why statins cause side effects, particularly damage to the liver.
Along the way, they also looked at the relationship between low, intermediate and high doses of statins and rates of newly diagnosed cancer. They discovered higher rates of newly diagnosed cancer among patients with lower achieved LDL levels. The new cancers were not of any specific type or location.
In an accompanying editorial, Dr. John C. La Rosa of the State University of New York Downstate Medical Center in Brooklyn, said it's too early to sound any alarm bells and noted that most studies don't show patients with cholesterol levels low enough to be in the range where the issue of increased cancer risk comes up.
He notes that one explanation for the findings is that patients with low LDL live longer and are therefore more likely to eventually develop cancer.
The coronary benefits of statin treatment are well proven, added Dr. James Dove, president of the American College of Cardiology, and this data is not enough to cause a change in current statin recommendations.
"While these results raise important new questions about statin use, they do not demonstrate a causal relationship between statins and cancer," he said. "This study is hypothesis-generating, not hypothesis-proving."
As for the research into the side effects of statins, the investigators found that liver toxicity levels increased with higher statin dosage. Based on their findings, they concluded that moderate-dose therapy with multiple medications including statins may prove to be preferable to high-dose therapy with statins alone.
