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Do ARBs Cause Cancer?

In June the British medical journal Lancet published an article that suggested that a group of drugs used to treat high blood pressure increase the risk of developing cancer. The drugs are called angiotensin receptor blockers (ARBs). Those currently available in the United States include Atacand (candesartan cilexetil), Avapro (irbesartan), Benicar (olmesartan), Cozaar (losartan), Diovan (valsartan), Hyzaar (losartan), Micardis (telmisartan), and Teveten (eprosartan mesylate).

As you know, I have written extensively about the dangers of various classes of drugs. My conclusions are drawn primarily from the drugs’ mechanisms of action – what they do in the body. For example, bisphosphonates such as Fosamax and Boniva block the body’s ability to renew bone and therefore place users at risk of future fractures due to excessive bone brittleness. Statin drugs block the body’s ability to manufacture coenzyme Q10, predisposing to muscle weakness and congestive heart failure.


To be consistent I must analyze the issue of ARBs and cancer in the same way – by examining what the drugs do in the body. On the basis of mechanism, I predict that the current cancer scare will prove to be a false alarm.


There are several reasons to question the validity of the Lancet study. It must be understood that the study in question was a reanalysis of data from previous studies. Those studies were not looking for a cancer link, and so it is doubtful that data regarding cancer incidence was accurately and completely reported. The fact that the Lancet study suggested the drugs increase the risk of developing cancer by approximately 1%, but do not increase the risk of dying from cancer supports the likelihood that the data being reviewed was incomplete or unreliable.


Only one drug, Micardis, was found to pose a statistically significant cancer risk. While it is possible that something unique to this drug is at work, that possibility is unlikely. Since the drugs all work by the same mechanism, a real effect should be consistent across all the drugs.


Most importantly, no one has been able to suggest a mechanism by which ARBs could increase the risk of cancer. To the contrary, a study demonstrating a twofold decrease in skin cancer in people taking ARBs was also published in June. It appeared in the journal Clinical Nephrology.


Unlike the Lancet report, which was based only on case reports, the Clinical Nephrology study was based upon an understanding of the mechanism by which ARBs work in the body. Angiotensin stimulates the growth of new blood vessels in the body, a process that tumors require to survive and grow. Kidney transplant recipients are at high risk for the appearance of skin cancer. The study authors reasoned that if the action of angiotensin were to be blocked fewer cancers would appear. The study was designed to look for the effect of ARBs on cancer development, and the results were as hoped; ARB use resulted in a dramatic reduction in the number of skin cancers appearing following a kidney transplant.


Always look beyond news headlines, which are chosen to sell newspapers and increase radio or television ratings. Apparently feeding upon people’s fear of cancer is more appealing to editors than reporting that cancer can be prevented. Why else would a report suggesting a 1 % increase in non-fatal cancers generate multiple news articles while a studydemonstrating that the drugs in question can cut the rate of skin cancer in half is ignored?

 

Dale Peterson, M.D.