A common drug used to treat blood pressure may actually be increasing the chances of lung cancer when taken over a long period of time.
A widely used hypertension drug comes under scrutiny in a new study.
People use angiotensin converting enzyme inhibitor drugs (ACEIs) for managing hypertension.
They are effective, and doctors consider them relatively safe when people take them for short periods of time.
Earlier studies have hinted that ACEIs might increase people’s cancer risk, but findings have not been conclusive; most existing studies only had access to relatively small sample sizes or for short periods of time.
Recently, scientists from McGill University in Canada set out to investigate whether ACEIs increase the risk of developing cancer, specifically lung cancer. They published the results earlier this week.
Scientists have theorized that ACEIs might increase lung cancer risk by encouraging a buildup of two particular substances in the lungs: bradykinin and substance P.
Bradykinin is a peptide that causes blood vessels to dilate, reducing blood pressure; substance P, which is also a peptide, can act as a neurotransmitter.
Scientists have associated both of these compounds with lung cancer tissue: bradykinin is thought to directly stimulate the growth of lung cancer, while lung cancer tissue expresses substance P, possibly encouraging tumor proliferation.
Blood pressure drug and lung cancer
The researchers involved in the current study, led by Prof. Laurent Azoulay, dipped into the medical records of almost 1 million people in the United Kingdom. All patients had started taking blood pressure-reducing drugs in 1995–2015.
The participants were 18 years of age or older and had no previous incidence of cancer. The research team followed them for an average of 6.4 years. Across this time period, doctors made almost 8,000 lung cancer diagnoses.
The scientists compared the risks of developing lung cancer in individuals who had started taking ACEIs against those who were taking a group of blood pressure drugs called angiotensin receptor blockers (ARBs).
To reduce statistical clutter, they made allowance for other factors that can influence lung cancer risks, such as smoking tobacco, age, body mass index (BMI), alcohol use disorders, and a history of lung disease.
They concluded that taking ACEIs was associated with a 14 percent increase in lung cancer risk, compared with taking ARBs.
The relationship was apparent after an individual had taken the drug for 5 years. As they continued to use the drug, their risk steadily increased. Individuals who took the drug for a decade or more had a particularly pronounced risk that increased by 31 percent.
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