Some blood pressure drugs have been linked to an increased risk of lung cancer, according to a new observational study.
The research, led by McGill University, Canada, found that angiotensin converting enzyme inhibitor drugs (ACEIs) – particularly if used for more than five years – is associated with the risk when compared with angiotensin receptor blockers (ARBs).
Writing in The BMJ, the scientists say that although the risk for individual patients is modest, ACEIs are widely prescribed, which means the “small relative effects” could translate into “large absolute numbers of patients at risk for lung cancer.”
The findings “should be replicated in other settings, particularly among patients exposed for longer durations”, they add.
In what is the largest study to assess this specific association, Professor Laurent Azoulay analysed UK primary care records for nearly one million adults who started taking a new antihypertensive drug between 1995 and 2015 to establish if there is an association, after previous research reported inconsistent results.
The patients, none of whom had had any previous cancer, 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.
After taking account of factors that could potentially influence the findings, such as smoking history, ACEI use was associated with an overall 14% increased risk of lung cancer compared with ARBs – 1.6 cases per 1000 person years compared with 1.2.
The association increased the longer the ACEIs were taken and for those who used them for more than 10 years, there was a 31% increased risk.
The researchers say that because it is an observational study, they can neither draw any firm conclusions about cause and effect nor rule out the possibility that other unmeasured factors, such as socioeconomic differences, diet, and family history of lung cancer, may have affected the results.
However, the findings in the study were consistent after further analyses to test the strength of the results.
The researchers have recommended additional studies, with long term follow-up, to investigate the effects of these drugs on incidence of lung cancer.
British Heart Foundation medical director Professor Sir Nilesh Samani called for more research.
He said: “ACE inhibitors have been prescribed for many years to treat heart failure and high blood pressure, and are undeniably life-saving. The suggested link to lung cancer is a surprise, and based on an observational study.
“While the authors have tried to look for other reasons for the link, they accept there’s always the possibility it’s down to factors they didn’t measure.”
Hicks B, Filion K, Yin H et al. Angiotensin converting enzyme inhibitors and risk of lung cancer: population based cohort study. The BMJ. October 2018. BMJ 2018;363:k4209. http://dx.doi.org/10.1136/bmj.k4209
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