Some widely used blood pressure drugs may be associated with an increased risk of cancer, researchers found in a new study.
In a meta-analysis of nine published studies the blood pressure drugs called angiotensin-receptor blockers were associated with a modest but statistically significant 8 percent increase in the relative risk of a new cancer, according to Dr. Ilke Sipahi, and colleagues at Case Western Reserve University School of Medicine in Cleveland, Ohio.
Angiotensin-receptor blockers, or ARBs, are a drug class that includes Diovan, Cozaar, Micardis, and Atacand.
A full list of the study drugs can be found at the bottom of the story.
On the other hand, there was no increase in the risk of dying from cancer, perhaps because follow-up in the trials was too short, the researchers said online in the medical journal The Lancet.
The findings are "disturbing and provocative" and raise important safety issues both for doctors and regulators, argued Dr. Steven Nissen, of the Cleveland Clinic, in an accompanying Comment article in the journal.
Nissen said regulators should immediately review the possible association and "promptly report" what they find. In the meantime, he added, doctors should use the drugs with caution, perhaps prescribing angiotensin-converting enzyme inhibitors instead.
The study comes only days after the U.S. Food and Drug Administration said it was evaluating data from two clinical trials in which patients with type 2 diabetes taking the blood pressure drug olmesartan (Benicar) had a higher rate of death from a cardiovascular causes compared to patients taking a placebo. Olmesartan was not studied by Sipahi and colleagues in the recent article.
Sipahi told MedPage Today that the study is only a first cut at the issue and needs to be followed by prospective studies aimed at the issue. But, he noted, "tens of millions of patients" use the drugs, so even a small increase in risk could be important.
Other experts, though, challenged the findings, saying the study was flawed. And many said they feared that publicity would lead to patients stopping what are very often life-saving medications.
The study is "unconvincing and irresponsible," said Dr. Henry Black, of New York University School of Medicine and past president of the American Society of Hypertension.
In response to a query from ABC News and MedPageToday, Black said the follow-up in the nine studies was so short that "the most you could blame a drug for in such short studies would be that it 'unmasked' a cancer that was already present." Also missing from the analysis, he said, was a plausible biological mechanism by which the drugs could cause cancer.
The researchers "pooled" trials with varying approaches and methods, Black said. "For these sorts of analyses to really be useful, the increase in risk should be at least 500 percent or more to get my attention," he said.
Black urged "responsible" coverage of the issue, adding "every caution must be taken to avoid patients stopping drugs that undoubtedly save lives."
The finding is "unexpected and certainly warrants scrutiny," said Dr. Franz Messerli, of St Luke's-Roosevelt Hospital in New York City. But, he added in an e-mail, "there is little, if any, biological plausibility that a drug exposure of a few years only would increase the risk of new cancer diagnosis."