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Continuing smoking after cancer diagnosis increases risk of adverse cardiovascular event

Ongoing smoking following a cancer diagnosis, elevates the risk of adverse cardiovascular disease (CVD) events, according to the findings of a study by Korean researchers.

Emerging data indicates how continued smoking following a cancer diagnosis increases the risk of cardiovascular disease mortality. In fact, nearly 20 per cent of cancer survivors continue to smoke. However, the differential effect on adverse cardiovascular outcomes, of either quitting smoking, cutting down or continuing to smoke is less clear.

The current study, published in the European Heart Journal, assessed the effect of changes to smoking habits on adverse cardiovascular outcomes. Smoking status was assessed two years before and three years after a cancer diagnosis. Participants were categorised as non-smokers; quitters, initiators and relapsers, and continued smokers. The primary outcome was a composite of CVD events, comprising hospitalisation for myocardial infarction or stroke, or CVD death.

Smoking status and adverse cardiovascular outcomes

Among 309,095 cancer survivors with a median age of 59 years (51.8% women), 80.9% were non-smokers, 10.1% quit, 7.5% initiated or relapsed to smoking and 7.5% continued to smoke.

During a median follow-up of 5.5 years, 10,255 new CVD events occurred. Using non-smokers as the reference point, the adjusted hazard ratio (aHR) for a CVD event among quitters was 20% higher (aHR = 1.20, 95% CI 1.12 – 1.28). But among those who continued to smoke, the risk was 86% higher (aHR = 1.86, 95% CI 1.74 – 1.98).

There were clear benefits for those who quit smoking. For example, the CVD event risk was significantly lower among those who quit compared to participants continuing to smoke (aHR = 0.64, 95% CI 0.59 – 0.70). These findings were consistent across both sexes as well as when classifying participants according to their primary cancers. Among those who continued to smoke, cutting down had no effect on their risk of a CVD event (HR = 0.99, 95% CI 0.80 – 1.22).

The authors suggested that continued smoking after a cancer diagnosis and its association with CVD events highlighted the urgent need for initiatives to promote smoking cessation and prevent smoking initiation and/or relapse among patients with cancer.

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