Low cholesterol levels may raise cancer risk

26 July, 2007:

Reducing cholesterol levels may lower the risk of heart disease, but reducing cholesterol to very low levels could raise the risk of cancer, researchers in the US have reported.

Patients who took statin drugs to lower their cholesterol had a slightly higher risk of cancer, though 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 low-density lipoprotein (LDL), or the so-called bad cholesterol, when compared to patients with higher LDL levels.

Dr Richard Karas of Tufts University School of Medicine in Boston and his colleagues did not look directly at patients for their study, which has been published in the Journal of the American College of Cardiology.

They did what is known as a meta-analysis, looking at the records of 41,173 patients in 23 different trials of statins.

According to Dr Richard Karas, 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.

Some experts cautioned that the general public could misunderstand the meaning of the study.

Dr John LaRosa of the State University of New York Downstate Medical Center in Brooklyn, who wrote a commentary in the journal, said: “You have to be careful about these things, because people stop taking their statins because they are afraid of cancer and then they die of heart attacks.”

Statins are the world’s top-selling drugs, fetching 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 that some of the beneficial effects may come from the drug’s effects on inflammation in the body.

But people with extra-low cholesterol may have a higher risk of Parkinson’s disease. Statin drugs can also damage the liver and muscles.

Now, the study by Dr Karas and his team renews concerns about cancer as well.

An analysis of 13 statin clinical trials published in November 2005 and involving over 41,000 patients had found higher rates of newly diagnosed cancer among patients with lower cholesterol.

Researchers found one additional cancer case for every 1,000 patients with low cholesterol levels when compared with patients with higher levels. The new tumours were not of any specific type.

However, they said it is still unclear whether there is a direct link between the use of statins and increased risk of cancer.

This analysis, stressed Dr Karas, does not implicate the statin in increasing the risk of cancer. “The demonstrated benefits of statins in lowering the risk of heart disease remain clear; however, certain aspects of lowering (cholesterol) with statins remain controversial and merit further research,” he added.