Popular Blood Pressure Drugs Linked to Higher Cancer Rate

Angiotensin-receptor blockers, a common class of blood pressure medications, have been linked to an increased risk of cancer in a recent study. These widely used drugs include medicines such as Boehringer's Micardis, Merck's (MRK) Cozaar and Hyzaar, and Novartis's (NVS) Diovan.

Researchers, led by Dr. Ilke Sipahi of Case Western Reserve University School of Medicine in Cleveland, found that the incidence of new cancers in people taking an angiotensin-receptor blocker was 7.2%, compared to a 6% incidence in those taking a placebo -- a modest but statistically significant increase -- according to the study published online in The Lancet.

The widely used drugs generated some 82 million prescriptions in 2009, racking up $25 billion in worldwide sales according to IMS Health. Many of them are blockbusters: Combined sales of Novartis's Diovan and a Co-Diovan were $6 billion last year; Merck's Cozaar and Hyzaar had combined sales of $3.6 billion; and Micardis had sales of $1.5 billion for Boehringer. Other examples include AstraZeneca's (AZN) Atacand, Bristol-Myers Squibb's (BMY) and Sanofi-Aventis's (SNY) Avapro and Daiichi Sankyo's Benicar.

It's no wonder then, that the study immediately stirred criticism from drugmakers. German pharmaceutical Boehringer Ingelheim, maker of Micardis, which was the drug taken by 85.7% of those in the study, disputed the result, saying its own data "contradicts the conclusions about an increased risk of potential malignancies." It further criticized such meta-analyses, saying they "have well-recognized limitations."

Patients Urged to Keep Taking Their Medications

But it wasn't just the drug companies. Other experts also challenged the findings, saying the study was flawed. The study is "unconvincing and irresponsible," Dr. Henry Black of New York University School of Medicine and past president of the American Society of Hypertension, told MedPage.

Even those who accepted the results as interesting and acknowledged that the study merits further examination, also urged caution as the association between taking the angiotensin-receptor blockers and increased cancer was modest and the result not definitive. They all encouraged patients not to stop taking their medications.

Still, in a commentary published with the study, Dr. Steven Nissen of the Cleveland Clinic argued that the findings are "disturbing and provocative," and urged action from both doctors and regulators.

Indeed the U.S. Food and Drug Administration just last week said it was looking into studies in which Daiichi Sankyo's drug Benicar seemed to have a higher death rate.

The trials the researchers studied included data on four of the seven available angiotensin-receptor blockers -- Cozaar, Atacand, Micardis and Diovan -- but will likely stir caution among users of them all. Still, even Sipahi acknowledged "meta-analyses are generally considered less convincing," and warned patients not to stop taking their drugs.