Millions of people around the world rely on medication to lower their blood pressure, but a new study has found some of these drugs could increase the risk of lung cancer.
Patients using a common class of drugs known as angiotensin converting enzyme (ACE) inhibitors are 14 per cent more like to develop lung cancer than patients using angiotensin receptor blockers (ARBs), according to an observational study conducted by McGill University and published in The BMJ. Both medications are used to treat hypertension, although they each target different proteins and can have different side effects.
ACE inhibitors are prescribed not only to lower blood pressure, but to also reduce the risk of heart disease, stroke, heart failure and even death. They are known in Australia under the brand names Coversyl and Tritace, but are also known as Altace, Captopril, Cilazapril and Enalapri in other parts of the world.
Researchers analysed 992,000 health records in the United Kingdom of patients who were prescribed blood pressure medication between 1995 and 2015. After following results for six years, researchers noticed those taking ACE inhibitors were more likely to develop lung cancer and the risk increased the longer patients used the medication. People who took the medication for a decade had a 31 per cent increased chance of a lung cancer diagnosis.
The study found it was possible that ACE inhibitors can cause a build-up of a chemical called bradykinin on the lung, which can cause blood vessels to dilate and in turn, lead to lung cancer. Researchers are still trying to determine the relationship between lung cancer and high blood pressure medication and note that because it was an observational study, other factors such as diet, family history and socioeconomic differences could play a role in the findings.
“Although the magnitudes of the observed estimates are modest, these small relative effects could translate into large absolute numbers of patients at risk for lung cancer, so these findings need to be replicated in other settings,” researchers wrote.
The NHS in the United Kingdom said the 14 per cent increased risk is “extremely small” when compared to other lung cancer risk factors.
“For example, smoking 15 to 24 cigarettes a day increases the risk of lung cancer in men by around 2,600 per cent (making their risk around 26 times higher),” it said in a statement.
In the study, there was 1.2 lung cancer cases for every 1,000 people per year in the ARB group, compared to 1.6 cases in the ACE group. The NHS also said people who take these medications should not stop as a result of the findings.
“What we can say with confidence is that untreated high blood pressure, which can cause heart attacks and stroke, is a far greater threat to your health than taking ACE inhibitors,” it said. “So you should never stop taking any prescribed blood pressure medication without talking to your GP.”
The NHS also said that although alarming, there is nothing at this stage to represent a definite risk.
“If you are taking an ACE inhibitor and are worried, remember that these drugs are known to protect against heart attacks and strokes,” the NHS statement read. “At the moment, the link with lung cancer is not proven.”