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Blood pressure news
Experts say ARB cancer risk research is inconclusive
UK experts are urging people not to stop taking the blood pressure lowering medicines ARBs, after a US study claimed that the drugs may slightly affect cancer risk.
In a study published in the Lancet Oncology, researchers from Case Western University School of Medicine who reviewed a series of previous cancer trials, known as a meta-analysis, found that the common class of blood pressure drugs called angiotensin-receptor blockers (ARBs) may be linked with a slightly increased risk of developing cancer.
But other experts, including the Blood Pressure Association, say that no firm conclusions can be drawn from the study and that people who take ARBs should not stop using their prescribed medicines without first talking to their GP.
What are ARBs?
ARBs are commonly used to treat people with high blood pressure, heart failure or diabetes-related kidney damage. They work by blocking the receptor for a hormone called angiotensin II, which increases blood pressure.
What did this study find?
Scientists at Case Western Reserve University School of Medicine in Cleveland, US, examined the effect of ARBs on the development of new cancers, by analysing the results of five previous trials, known as a meta-analysis. The looked at studies on new cancers (involving 61,590 patients), five trials on common solid-organ cancers such as lung, prostate and breast cancer (68,402 patients) and eight trials on cancer deaths (93,515 patients).
Overall, findings showed that patients taking ARBs had a slightly increased likelihood of new cancer diagnosis compared with patients in control groups (7.2% vs 6.0%), representing an absolute increase of 1.2 per cent.
Among the solid-organ cancers examined, only the risk of lung cancer was significantly increased in patients taking ARBs compared with controls (0.9% vs 0.7%), which represents an increase of just 0.2 per cent.
Most patients involved in the trials - all of which were published before November 2009 - had received an ARB called telmisartan. However, the studies only looked at three ARBs (telmisartan, losartan and candesartan), which means that these findings cannot be applied to ARBs in general.
What did the authors' conclude?
The authors of the study concluded: "The finding of a 1.2 per cent increase in absolute cancer risk over an average of four years needs to be interpreted in view of the estimated 41 per cent background lifetime cancer risk. Given the limited data, it is not possible to draw conclusions about the exact risk of cancer associated with each ARB. Our findings warrant further investigation."
What does the BPA and other experts think?
Mike Rich, Executive Director of the Blood Pressure Association, said: “This study does not prove that ARBs cause cancer and further investigation is needed to see if that really is the case or not.
"However, there is abundant evidence to show that ARBs are a well-established and proven treatment for high blood pressure. What is important to remember is that this kind of drug saves countless lives by allowing the good management of high blood pressure in people who may otherwise be at great risk of stroke or heart attack.
"So our advice is, please do not stop taking your medicines, and if you do have any concerns, speak to your GP."
Professor Mark Caulfield, of St Bart’s Hospital, London, and a Trustee of the Blood Pressure Association, said: “This meta-analysis should in my view have been conducted differently with comprehensive data on cancer. Based on this study, there is, in my view, no reason for patients to change medication.”
Cancer Research UK said: "At the moment there isn't enough evidence to draw any firm conclusions about how these particular blood pressure drugs might affect cancer risk and this will need further investigation. People shouldn't stop taking these drugs on the basis of this research. If they're concerned they should speak to their GP."
Click here to read the full paper published in Lancet Oncology on 14 June 2010.