Many adults continue smoking after cancer diagnosis, despite CV benefits of quitting
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Key takeaways:
- Quitting smoking after a cancer diagnosis reduces CV risk by 36% compared with continuing smoking.
- More than 40% of smokers opted to continue smoking after their cancer diagnosis.
Quitting smoking after a cancer diagnosis can reduce CVD risk by 36% compared with continued smoking, yet 40% of patients who smoked opted to continue after a diagnosis, data from the Korean National Health Insurance Service show.
“A cancer diagnosis is an extremely stressful life event, which often leads to significant changes in a person's lifestyle,” Hyeok-Hee Lee, MD, of the departments of preventive medicine and internal medicine at Yonsei University College of Medicine in Seoul, South Korea, said in a press release. “Smoking, in particular, is a health-related behavior that can be heavily influenced by mental distress. However, little was known about the relationship between changes in smoking habits after a cancer diagnosis and the risk of cardiovascular disease — the leading cause of non-cancer-related death among cancer survivors.”
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CVD highest for continuing smokers
Lee and colleagues analyzed data from 309,095 adults newly diagnosed with cancer from 2006 to 2013 and free of CVD at baseline, using data from the Korean National Health Insurance Service. The median age of adults was 59 years and 52% were women. Smoking status was assessed by a self-reported questionnaire during exams within 2 years before the cancer diagnosis and the last examination within 3 years after the cancer diagnosis. Researchers stratified patients into four groups according to changes in smoking habits between the first and second exams: those who were not smoking in both exams (sustained nonsmokers); those who were smoking in the first exam but were not smoking in the second exam (quitters); those who were not smoking in the first exam but were smoking in the second exam (initiators or relapsers); and those who were smoking in both exams (continuing smokers). The median time was 0.5 years between the first exam and cancer diagnosis and was 2 years between cancer diagnosis and the second exam.
The primary outcome was a composite CVD event, defined as the first hospitalization for MI or stroke or CV death.
The findings were published in the European Heart Journal.
Within the cohort, 80.9% were sustained nonsmokers, 10.1% quit smoking, 1.5% initiated or relapsed smoking and 7.5% continued smoking after their cancer diagnosis.
During a median follow-up of 5.5 years, 10,255 new CVD events occurred.
The cumulative incidence of CVD events was the highest among continuing smokers, followed by initiators/relapsers, quitters and sustained nonsmokers. Compared with sustained nonsmokers, adjusted HRs for CVD events were 1.2 among quitters (95% CI, 1.12-1.28), 1.51 for initiators/relapsers (95% CI, 1.33-1.71) and 1.86 for continuing smokers (95% CI, 1.74-1.98).
When compared with continuing smokers, quitters were 36% less likely to develop CVD during follow-up (adjusted HR = 0.64; 95% CI, 0.59-0.7). Findings were consistent for all components of the primary outcome and across both sexes.
Among 15,392 continuing smokers with data on tobacco consumption per day, 20.2% reduced their daily tobacco intake by at least half after their cancer diagnosis, according to the researchers.
Smoking reduction without cessation was not associated with a lower risk for CVD events.
Different cancers, different smoking patterns
The researchers also found that patterns of smoking habit change varied across cancer types. The proportion of initiators/relapsers and continuing smokers combined was the highest among those with urinary tract cancer (15.6%), male genital organ cancer (14.2%) and hepatobiliary, pancreatic or other gastrointestinal cancer survivors (14.1%), and was the lowest among breast cancer (1%), female genital organ cancer (2.1%), endocrine cancer (5.7%) and lung cancer survivors (6.5%).
“Our results reinforce the existing evidence on the well-known cardiovascular risks of tobacco smoking and emphasize the benefits of smoking cessation, even for cancer survivors,” Lee said in the release. “Additionally, the finding that over 40% of patients who had been smoking before their cancer diagnosis continued to smoke afterwards highlights the need for more robust efforts to promote smoking cessation among cancer survivors, who already have an elevated risk of cardiovascular disease compared to their peers.”
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