Professor Shin Dong-wook's Team at Samsung Seoul Hospital Analyzes 890,000 National Screening Subjects
Comparison of Cancer Risk According to Changes in Smoking Amount
Quitting Smoking Is Best, but Reducing Smoking Also Slightly Lowers Cancer Risk
[Asia Economy Reporter Lee Gwan-ju] A study has found that if you are struggling to quit smoking, at least reducing the amount you smoke can lower your risk of developing cancer.
A joint research team led by Professor Shin Dong-wook of Samsung Seoul Hospital and Professor Yoo Jung-eun of Seoul National University Hospital Gangnam Center analyzed cancer risk among 893,582 participants with a history of smoking who took part in the national health screening program, and published their findings in the American Cancer Society journal Cancer on the 6th.
The research team tracked cancer incidence through 2018 based on changes in smoking amounts, using smoking history reported twice during national health screenings in 2009 and 2011. The study subjects were aged 40 or older, and during an average follow-up period of 6.1 years, 50,869 were diagnosed with cancer. Among these, 81% were reported to be directly or indirectly related to smoking.
The team categorized participants into four groups based on their average daily cigarette consumption: quitters, reducers, maintainers, and increasers. Only 20.6% successfully quit smoking. Those who reduced their smoking accounted for 18.9%. Nearly half, 45.7%, maintained their usual smoking habits. A significant 14.8% increased their smoking by more than 20% compared to before.
When comparing cancer risk among these groups, those who successfully quit had the lowest risk compared to the maintainers. Overall cancer risk was reduced by 6%, smoking-related cancers by 9%, and lung cancer by 21%. Even if they did not quit completely, reducing smoking showed a beneficial effect in lowering cancer risk. Those who reduced their smoking by more than 50% had a 4% lower overall cancer risk, 5% lower smoking-related cancer risk, and 17% lower lung cancer risk compared to maintainers.
However, if quitters resumed smoking, their cancer risk rose again. The research team additionally analyzed 682,996 people who had data from two health screenings plus the 2013 screening, comparing cancer risk between those who remained quit and those who relapsed. Even if relapsers reduced their smoking by more than 50% compared to their previous amount, their risk of smoking-related cancers increased by 19% and lung cancer risk by 48% compared to those who maintained abstinence.
Professor Shin Dong-wook explained, “There is no safe level of smoking, so for smokers, quitting immediately is best for health. Even if you fail to quit, do not be discouraged; first reduce your smoking enough to lower risk, and ultimately free yourself from cigarettes to reduce cancer concerns.” Professor Yoo Jung-eun added, “There has been a lack of research on how resuming smoking after quitting affects cancer risk. Since cancer risk can increase with relapse, those who have successfully quit must maintain abstinence.”
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