Blood pressure medications linked to increased risk of cancer

According to a study published in the British medical journal The Lancet Oncology, certain blood pressure medications may be linked to increased risk of cancer.

The drugs in question are called angiotensin-receptor blockers or ARBs,  AT1-receptor antagonists or sartans, are a group of pharmaceuticals which modulate the renin-angiotensin-aldosterone system. Their main use is in hypertension (high blood pressure), diabetic nephropathy (kidney damage due to diabetes) and congestive heart failure.

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.

Dr. Ilke Sipahi, a heart failure expert,  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. Dr. 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, 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.'”

Dr. 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 Dr. 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.

Below is a list of ARBs drugs:

Losartan (marketed by Merck & Co. under the trade name Cozaar)
Irbesartan  (jointly marketed by sanofi-aventis and Bristol-Myers Squibb under the trade names Aprovel, Karvea, and Avapro)
Olmesartan (Benicar, Olmetec)
Candesartan (marketed by AstraZeneca and Takeda Pharmaceuticals, commonly under the trade names Blopress, Atacand, Amias and Ratacand)
Valsartan (marketed by Novartis under the trade name Diovan)
Telmisartan (Micardis by Boehringer Ingelheim)