Statins and cancer

Have you ever thought about what else, other than treating high cholesterol, your statin drugs are doing in your body?  Since statins are the largest-selling prescription drugs in this country, doctors have wondered if they may have benefits beyond the heart—including their effect on cancer. Indeed, statins produce a substantial reduction in the risk of stroke. And although the results are less conclusive, statins are being studied for possible benefits against a variety of diseases, from cataracts and dementia to chronic lung disease, osteoporosis, and the flu. And now attention is turning to statins and cancer.

Not to worry

In the early days, some scientists worried that statins might protect the heart at the cost of an increased risk of cancer. Their concern was based on experiments showing that several types of lipid-lowering drugs, including statins, appeared to increase the occurrence of malignancies in rodents. But men are not mice, and those fears have proved groundless. For example, the Heart Protection Study of more than 10,000 statin users and the Scandinavian Simvastatin Survival Study of more than 2,000 users found no increased cancer risk. More recently, a meta-analysis of 14 statin trials involving more than 90,000 individuals agreed that statins do not increase the risk of cancer.

Perhaps to hope

Statin safety is good news. But now that doctors have put worries about statins and cancer to rest, they are asking a radically different question: Might statins actually reduce the risk of cancer?

Their hope is based mainly on a large series of laboratory experiments. Although the details vary, the basic idea is to grow cancer cells in test tubes with or without a statin drug in the culture medium. Many labs from around the world have been involved, with different results. In general, though, scientists agree that statins are able to slow the growth of cells from human cases of prostate cancer, bladder cancer, breast cancer, and other malignancies. Several mechanisms have been identified. Statins may reduce the activity of genes that turn cells cancerous and increase the activity of other genes that protect cells from turning cancerous. They may starve the blood supply to growing tumors. In addition, statins may reduce a cancer cell’s ability to spread and may even encourage cancer cells to commit suicide (a process called apoptosis). Finally, some results suggest that statins may strengthen the effects of standard cancer drugs or radiation.

Taken together, these results are interesting, even hopeful. But it’s a long way from the lab to the clinic, and it will be years before we know if these basic experiments translate into practical benefits. Indeed, neither a 2006 meta-analysis of 26 statin trials nor the three large studies cited above to support the safety of statins found any protective effect against cancer. But the trials were designed principally to study heart disease, and they were relatively brief, especially compared to the many years it takes for most cancers to develop and grow.

While the results are mixed, some clinical observations do suggest benefit. A Canadian study of 6,721 people 65 years of age and older linked statin use to a 28% decline in the risk of cancer. In a 2004 study of 3,129 patients with cancer and 16,976 people without the disease, statin use for four years or longer was linked to a 20% reduction in the incidence of malignancy. Similarly, a 2005 investigation of 334,754 Danes reported that statin users enjoyed a 14% lower risk of cancer than non-users. Moreover, the apparent benefit did not depend on cholesterol reduction per se, since statin users were 27% less likely to develop cancer than those who used other types of lipid-lowering drugs.

Statins for cancer?

Not yet.

There are several good reasons for doctors to prescribe a statin drug. Most often it’s a high LDL (“bad”) cholesterol level, but it’s also clear that patients with diabetes, heart disease, or other forms of atherosclerosis can benefit from statin therapy even if they start out with normal LDL levels. And if new trends continue, statin therapy may soon be extended to some vulnerable individuals with low LDL levels.

Cancer is another matter. As for cataracts, chronic lung disease, and dementia, there are hopeful hints that statin therapy may help. But hints and hopes are not enough; until proof is available, doctors should not prescribe a statin simply to reduce the risk of any of these conditions. Still, patients who need a statin for cardiovascular protection may be heartened by the hope that cancer prevention may be a “side effect” of these important medications. And even without a statin, people who reduce their consumption of saturated fat can expect a number of health benefits, especially lower cholesterol levels and reduced cardiac risk.

What has your experience with the statin drugs been?

Julie K. Silver, M.D., is an assistant professor in the Department of Physical Medicine and Rehabilitation at Harvard Medical School. She is also the Chief Editor of Books for Harvard Health Publications.

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