06/13/2013 05:45 pm ET Updated Aug 13, 2013

Statins and Cancer: More Questions Than Answers

A recent study that analyzed Danish death certificates and medical reports between 1995 and 2007 concluded that deaths due to cancer were reduced by 15 percent in patients taking statins. There was no association between lower death rates from cancer and the dose or type of statin used. It was suggested that this benefit might be related to blocking cholesterol synthesis, but a meta-analysis of data from 26 cholesterol-lowering statin trials found no evidence of such a relationship.

Critics point out that in animal studies, statins are carcinogenic in doses that produce blood concentrations similar to those achieved in clinical use. In humans, it is well established that carcinogens like asbestos and tobacco may take decades to surface, even after exposure has stopped. If statins are carcinogenic, the two malignancies most likely to be detected early are cancers of the skin and breast. In that regard, the current "epidemic" of non-melanoma skin cancers has been linked to the widespread use of statins, and particularly simvastatin in one report. In the CARE (Cholesterol And Recurrent Events) trial, 12 of 286 women taking pravastatin developed breast cancer compared to only 1 of 290 in the placebo group, although this was not mentioned in the abstract. Several in the pravastatin group had a recurrence of breast cancer, and the sole patient in the control group, who died, also had a history of breast cancer.

Pravastatin was associated with a 51 percent increase in prostate cancer in a 15-year follow-up of one large trial and an increase in statin-related malignancies was found in several others. In patients who took low dose simvastatin for six years, those whose cholesterol was lower than 160 had three times more cancer deaths than controls with normal or high cholesterol, although this was again was not mentioned in the abstract. A meta-analysis of 23 large statin trials similarly concluded that the magnitude of LDL lowering was directly correlated with increased risk of cancer. In addition, numerous studies of healthy people also show that a low cholesterol per se is associated with increased risk of cancer, even when measured 10 to 30 years earlier.

Low cholesterol proponents cite studies that purportedly show statins can prevent or inhibit cancer, even though this is not related to lipid lowering. And because such favorable studies receive extensive coverage in the media and benefits are often hyped, more patients are likely to take statins, particularly those with cancer. This is especially true, since safety concerns are suppressed, minimized or even ignored in reports on studies containing negative safety information. As emphasized elsewhere, it is important to recognize that patients taking statins are much more likely to have had elevated cholesterols for a decade or more compared to controls. And just as low cholesterol is a risk factor for cancer, a high cholesterol may have had a protective effect, as has been demonstrated for atherosclerosis and infection.

At present, it is impossible to prove that statins have any effect on the development or spread of cancer. It may take decades for a carcinogenic effect to surface, and by then, a relationship may not be recognized, especially if statins have been discontinued. Nevertheless, ever since the CARE study demonstrated an increase in recurrent breast cancer with pravastatin, patients with a history of any malignancy have been excluded from all statin trials. Although no reason or explanation is given, this would appear to be a prudent decision.

Paul J. Rosch, M.D., FACP

Dr. Paul J. Rosch is Chairman of the Board of The American Institute of Stress, Clinical Professor of Medicine and Psychiatry at New York Medical College, Honorary Vice President of the International Stress Management Association and has served as Chair of its U.S. branch. You can follow AIS on Twitter, watch AIS videos on You Tube, become a fan of AIS on Facebook and subscribe to one or both free AIS magazines to receive the latest stress information and research from around the globe directly to your inbox.

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