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Blood Pressure Meds Linked to Cancer

(Ivanhoe Newswire) -- Angiotensin-receptor blockers (ARBs), drugs commonly used to treat high blood pressure, heart failure, and kidney damage due to diabetes, are associated with a modest increase in the risk of developing cancer.

ARBs work by blocking the receptors for angiotensin II -- a hormone that increases blood pressure. Although there are no major safety concerns associated with ARBs at present, a previous trial had reported a significantly increased risk of fatal cancers in patients receiving the ARB candesartan.

To further examine the effect of ARBs on the occurrence of new cancers, Ilke Sipahi and colleagues from Case Western Reserve University School of Medicine in Cleveland, analyzed all publicly available data from trials of ARBs published before November 2009. They analyzed new cancer data in five trials involving 61,590 patients, common types of solid-organ cancers (lung, prostate, breast) in five trials of 68,402 patients, and cancer deaths in eight trials including 93,515 patients. Most patients in the trials examined received the ARB telmisartan.

Overall, findings showed that patients taking ARBs had an increased likelihood of new cancer diagnosis compared with patients in control groups. Among the solid-organ cancers examined, only the risk of lung cancer was significantly increased in patients taking ARBs. No significant excess in cancer deaths was found, although the authors point out that tumor growth and treatment failure followed by death is a slow process and might not be recorded in trials with a short follow-up.

Additionally, data analyzed in the study was limited to three out of seven FDA-approved ARBs (telmisartan, losartan, and candesartan), so it is unknown if the other ARBs (valsartan, irbesartan, olmesartan, and eprosartan) are linked to a higher risk of new cancer incidence. The authors were quoted as saying, "Given the limited data, it is not possible to draw conclusions about the exact risk of cancer associated with each ARB."

"The increased risk of new cancer occurrence is modest but significant…,” they concluded. “However, the finding of a 1.2 percent increase in absolute cancer risk over an average of four years needs to be interpreted in view of the estimated 41 percent background lifetime cancer risk."

In an accompanying editorial, Steven E Nissen, from the Cleveland Clinic, was quoted as saying that these findings raise crucial drug safety questions. He called for pharmaceutical companies to supply complete ARB trial datasets to the regulatory authorities, so they can review the possible link between ARB use and cancer and, in the interim, urges ARBs to be used with caution.