WCLC 2025 - Posters & ePosters-P3.01.38 Effect of Smoking Cessation Duration on Lung Cancer Incidence: A Nationwide Retrospective Cohort Study in Korea

P3.01.38 Effect of Smoking Cessation Duration on Lung Cancer Incidence: A Nationwide Retrospective Cohort Study in Korea

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This nationwide retrospective cohort study in Korea investigated how the duration of smoking cessation influences lung cancer incidence. Using data from the Korea National Health Insurance Corporation, researchers analyzed medical and health examination records from 2002 to 2021, sampling approximately 50% of adults aged 50 who underwent health screenings between 2009 and 2013. Participants were categorized as never-smokers, former smokers, or current smokers. To address gender imbalances—particularly the higher proportion of women among never-smokers—propensity score matching was employed to create a balanced cohort.<br /><br />Key findings indicated that lung cancer risk significantly declined after just two years of smoking cessation when compared to current smokers. Moreover, after ten years of quitting, former smokers’ lung cancer risk reduced to levels comparable with never-smokers. An important nuance emerged regarding smoking intensity: individuals classified as light smokers (defined as 20 pack-years) reached this risk reduction milestone after seven years of cessation. Subgroup analyses by sex and pack-years supported these results, confirming that the benefits of cessation are substantial across different demographics and smoking histories.<br /><br />The study highlights that lung cancer risk does not abruptly normalize upon quitting but decreases progressively with longer cessation duration. These findings underscore the critical public health message that quitting smoking yields tangible reductions in lung cancer risk, even within a few years. It also emphasizes that earlier cessation offers greater risk reduction, motivating smokers to quit as soon as possible. Overall, this large-scale, population-based study from Korea provides robust evidence that sustained smoking cessation substantially lowers lung cancer incidence, ultimately aligning former smokers' risks with those who have never smoked over time.

Asset Subtitle

Myeong Geun Choi

Meta Tag

Speaker Myeong Geun Choi

Topic Risk Factors, Risk Reduction & Tobacco Control

Keywords

smoking cessation

lung cancer risk

retrospective cohort study

Korea National Health Insurance Corporation

propensity score matching

pack-years

never-smokers

former smokers

current smokers

lung cancer incidence