June 13th, 2010
06:36 PM ET
By Miriam Falco
Certain blood pressure medications may be linked to a modestly increased risk of cancer, according to a study published in the British medical journal The Lancet Oncology on Sunday.
However, researchers cannot say the exact risk of cancer for each of these drugs, so they are calling for more research. Some leading cancer and heart experts don't necessarily agree with the conclusions of this study.
The drugs in question are called angiotensin-receptor blockers or ARBs. ARBs block the chemical angiotensin II from having any effect on the heart and blood vessels, thus preventing blood pressure from going up. These drugs are commonly prescribed to patients with high blood pressure, heart failure and diabetes-related kidney disease.
Researchers at The University Hospitals Case Medical Center in Cleveland, Ohio, reviewed nine existing studies involving ARBs. "We were able to compile data of more than 60,000 patients," says lead study author Dr. Ilke Sipahi.
Sipahi, a heart failure expert, tells CNN that he and a few colleagues decided to analyze the published data about this class of drugs because several studies from the past few years suggested an increased cancer risk, and millions of people in the United States and around the world are taking these drugs.
He says their analysis found a 1.2 percent increased cancer risk for patients taking these drugs over four years. Sipahi says the current data suggest an "overall 10 percent increase in the risk of cancer diagnosis in patients on ARBs compared to placebo." The study also concludes that the risk for lung cancer was the highest. However, the study authors could not explain why these drugs might be causing cancer.
In an accompanying editorial, Dr. Steven Nissen, chairman of the Department of Cardiovascular Medicine at the Cleveland Clinic (which is not associated with UH Case Medical Center), suggests the results of this analysis require "urgent regulatory review."
Dr. Nicholas Vogelzang, an expert on several cancers and spokesman for the American Society of Clinical Oncology disagrees. He says he's fairly skeptical about the study conclusion because the only statistically significant rise was in lung cancer and "there's no direct mechanism to lung cancer should go up, but breast cancer went down. He adds that most cancers take 40 years to develop. "ARBs were not even on the market before 1995," says Vogelzang. "This gives me some pause."
The American Cancer Society's Dr. Michael Thun raises the same concern. "If the drugs caused this, then the increased cancer risk appeared much more quickly than is usually the case for solid tumors."
The American Heart Association's President Dr. Clyde Yancy actually takes ARBs to control his high blood pressure. He tells CNN in a statement, "These data raise a question, and a question only, regarding ARBs and the risk of cancer. Only non-small cell lung cancer was statistically increased and the extent of the increase was quite modest. We usually describe these kinds of findings as a 'signal' but given the modest result, perhaps this is more of a 'hint.'"
Yancy says the results of this study do not change anything for him – he will continue to take his blood-pressure lowering ARB. Study author Sipahi says he will continue to prescribe ARBs because for many patients the risk of dying from heart failure outweighs the possible risk of cancer development.
All the experts CNN spoke with recommend patients stay on their medications and talk to their doctor if they have any concerns.
CNN requested comment from several manufacturers of ARBs.
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