How low is too low in terms of cholesterol? That’s a question researchers, studying the cholesterol-lowering class of drugs called statins, recently found themselves asking.

While numerous studies support the heart-healty benefits of lowering low-density lipoprotein cholesterol, a new study actually links low LDL levels with an increased risk of developing cancer.

Click here to see a video on the link between cholesterol and cancer

Authors of the study, to be published in the July 31 issue of the Journal of the American College of Cardiology, initially set out to determine why statins cause certain side effects, including damage to the liver and muscle cells.

But what they found was another potentially negative side effect: Cancer.

The researchers found one additional incident of cancer per 1,000 patients with low LDL levels when compared to patients with higher LDL cholesterol levels. In their evaluation of randomized controlled statin trials published before November 2005, the researchers looked at 13 treatment arms consisting of 41,173 patients.

Researchers assessed the relationship between lowering LDL levels and rates of newly diagnosed cancer in each treatment arm. They also looked at the relationship between low, intermediate and high doses of statins in relationship to rates of newly diagnosed cancer.

While they found higher rates of newly diagnosed cancer among patients with lower LDL levels, the study was inconclusive as to whether it was the cholesterol or the statins causing the cancer. Also, the cancers suffered by people with lower LDL cholesterol varied and were not of any specific type or location.

Statin Users Should Continue Treatment

“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, in a news release. “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.”

Another study, released in June and published in an issue of the Lancet, called statins “remarkably” safe. The June study, based on a review of research published between 1985 and 2006 on the safety, efficacy and side effects of statins, also found the drugs to be well-tolerated.

At standard daily doses, which vary according to type, statins typically reduce LDL cholesterol in the blood by 30 to 45 percent. Six statins are available in most parts of the world: lovastatin, simvastatin, pravastatin, uvastatin, atorvastatin, and rosuvastatin.

“Since statins were first approved in 1987, their ability to reduce the risks of vascular death, non-fatal myocardial infarction, stroke, and the need for arterial revascularization has been shown by several large, high-quality randomized trials,” said the author of the June study, Dr. Jane Armitage, of University of Oxford, in a statement.

Karas said people with high cholesterol should not stop statin treatment as the benefits of the drug outweigh the risks. And an official with the American College of Cardiology cautioned people not to jump to negative conclusions about the drugs.

“While these results raise important new questions about statin use, they do not demonstrate a causal relationship between statins and cancer,” said Dr. James Dove, president of the American College of Cardiology. “This study is hypothesis-generating, not hypothesis-proving.”