Some BP drugs increase risk of lung cancer: BMJ

Certain BP drugs like ACE inhibitors are linked to increased risk of lung cancer, according to a new study.

According to a new study appearing in The BMJ today, use of BP lowering drugs like angiotensin-converting enzyme inhibitor drugs (ACEIs) is associated with an increased risk of lung cancer compared to another group of blood pressure drugs called angiotensin receptor blockers (ARBs). This risk is accentuated among people using ACEIs for more than five years.

Angiotensin-converting enzyme (ACE) inhibitors help relax blood vessel and sare effective drugs used to treat high blood pressure. They prevent an enzyme in your body from producing angiotensin II, a substance in body that narrows blood vessels and releases hormones that can raise your blood pressure.

There is evidence that ACEIs may increase the risk of lung cancer through the build-up of protein-like chemicals called bradykinin and substance P in the lung. These chemicals have been found on lung cancer tissue, and bradykinin may directly stimulate the growth of lung cancer.The risk for individual patients is modest but since ACEIs are widely prescribed, there may be large absolute numbers of patients at risk for lung cancer, say the researchers.

Professor Laurent Azoulay at McGill University in Canada and colleagues analysed UK primary care records for nearly one million patients who started taking a new antihypertensive drug between 1995 and 2015.All the patients were at least 18 years of age, with no previous cancer.They were followed up for an average of 6.4 years, during which time 7,952 cases of lung cancer were identified (a rate of 1.3 per 1000 person years).

The researchers after taking account of factors that could potentially influence the findings, including age, sex, weight (BMI), smoking status, alcohol related disorders, and history of lung diseases, found that use of ACEIs was associated with an overall 14% increased risk of lung cancer compared with ARBs (1.6 v 1.2 cases per 1000 person years).

The association of cancer with ACEIs were evident after five years of use and increased with longer durations of use, and patients who used ACEIs for more than 10 years there was 31% increased risk.

Although the magnitudes of the observed estimates are modest, the researchers point out that ACEIs are one of the most widely prescribed drug classes, “so these small relative effects could translate into large absolute numbers of patients at risk.” As such, they say these findings “should be replicated in other settings, particularly among patients exposed for longer durations.”

This is an observational study, so no firm conclusions can be drawn about cause and effect but this is the largest study to assess this specific association, and findings remained consistent after further analyses to test the strength of the results.

As such, the researchers conclude that the use of ACEIs is associated with an increased risk of lung cancer, and they call for “additional studies, with long term follow-up, to investigate the effects of these drugs on incidence of lung cancer.”

A 14% relative increase in lung cancer incidence may not translate to a large absolute risk but the findings become significant considering the extensive use of ACEIs globally.Therefore an individual patient should be aware of this risk and may take definitive decision regarding use of ACEIs consciously. Experts however feel that further studies with long term follow-up are needed to enhance the scientific evidence on the long term safety of these drugs.

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