Risk still low and patients should not suddenly stop taking these medications

A new study has suggested that the long-term use of commonly prescribed blood pressure medication called angiotensin converting enzyme inhibitor drugs (ACEIs), may be linked with a small increased risk of lung cancer. However, further research is needed to confirm these findings and concern about a relatively low long-term risk of lung cancer should be balanced against the benefits of ACEIs.

ACEIs are effective drugs used to treat high blood pressure (hypertension). High blood pressure is a major risk factor for cardiovascular disease. The higher your blood pressure the greater your risk of heart attack and stroke. Evidence suggests that ACEIs may increase the risk of lung cancer through the build-up of chemicals in the lung.

However, previous observational studies examining this association are limited and inconsistent.

To better understand this possible association, researchers led by Professor Laurent Azoulay at McGill University in Canada analysed records for nearly one million patients who started taking a new antihypertensive drug between 1995 and 2015.

Patients were at least 18 years of age, with no previous cancer, and were followed up for an average of 6.4 years, during which time 7,952 cases of lung cancer were identified.

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, use of ACEIs was associated with an overall 14 per cent increased risk of lung cancer compared with another commonly prescribed blood pressure medication called Angiotensin Receptor Blockers (ARBs).

Associations were evident after five years of use and increased with longer durations of use, particularly in patients who used ACEIs for more than 10 years (31% increased risk).

Although the magnitudes of the observed estimates are modest, the researchers pointed out that ACEIs were 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, and the researchers cannot 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, 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 concluded that the use of ACEIs was associated with an increased risk of lung cancer, and they called for “additional studies, with long term follow-up, to investigate the effects of these drugs on incidence of lung cancer.”

In a linked editorial, Associate Professor Deirdre Cronin Fenton from the Department of Clinical Epidemiology at Aarhus University in Denmark, said although a 14 per cent relative increase in lung cancer incidence might not translate to a large absolute risk, “the findings are important given the considerable use of ACEIs worldwide.”

Nonetheless, in an individual patient, concerns about the long-term risk of lung cancer “should be balanced against gains in life expectancy associated with use of ACEIs,” she wrote. “Further studies with long term follow-up are now needed to enhance the scientific evidence on the long-term safety of these drugs,” she concluded.

Commenting on the study’s findings, Dr Angie Brown, Consultant Cardiologist and Medical Director, Irish Heart Foundation said, “The study published today is a large population-based study and shows an association between the long-term use (over five years or more) of angiotensin converting enzyme inhibitor drugs (ACEIs) and a small increased risk of lung cancer. This is an important finding given the widespread use of ACEIs.

For individual patients, however, concerns about the possible long-term risk of lung cancer need to be balanced against the improvement in symptoms and life expectancy associated with the use of ACEIs in patients with heart failure. It is very important that patients don’t suddenly stop taking these medications without consulting their GP or cardiologist as this could lead to an increase in blood pressure with the associated increased risk of stroke and deterioration of heart failure. Patients should always discuss their medication with their GP or cardiologist before making any changes.

Further studies with long-term follow-up are now needed to see if these results are confirmed and to assess the long-term safety of these drugs.”

This study is published in the British Medical Journal

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