Risk-Adapted Lung Cancer Screening Starting Ages for Former Smokers.

Importance: The US Preventive Services Task Force (USPSTF) recommends lung cancer screening for individuals aged 50 to 80 years with a smoking history of at least 20 pack-years and 15 quit-years or less. This recommendation implies that former heavy smokers with at least 20 pack-years would be offered screening from 50 years of age onward or not at all, depending on a dichotomous classification by time since smoking cessation. Objective: To develop a more personalized lung cancer screening strategy that reflects individual risks by defining risk-adapted starting ages for screening according to time since cessation. Design, Setting, and Participants: This cohort study used longitudinal data from the population-based UK Biobank, which recruited participants in England, Wales, and Scotland between 2006 and 2010. Participants were 50 years or older, had no prior cancer diagnosis, and had at least 20 pack-years of smoking history. The following censoring dates were applied: December 31, 2020, for England; November 30, 2021, for Scotland; and December 31, 2016, for Wales. The present analysis was performed in April 2025. Exposure: Duration of smoking cessation (categorized into ≤5, 6-10, 11-15, and >15 quit-years). Main Outcomes and Measures: The association between smoking cessation time, pack-years, age, and 10-year lung cancer incidence was assessed using multivariable extended Cox proportional hazards models. Risk postponement periods (RPPs) were estimated from the regression coefficients for time since cessation and age. These RPP estimates were used to derive risk-adapted starting ages for lung cancer screening among former heavy smokers, using the USPSTF-proposed starting age of 50 years as a reference for the risk level of continuing heavy smokers. Results: A total of 86 035 former or current heavy smokers (mean [SD] age, 60.8 [5.3] years; range, 50-72 years), of whom 2109 (2.5%) were diagnosed with lung cancer, were included in the analysis. The RPPs for smoking cessation were 2.7 (95% CI, 0.0-5.3), 6.2 (95% CI, 4.4-7.9), 10.4 (95% CI, 8.5-12.4), and 17.1 (95% CI, 15.0-19.2) years for former heavy smokers who quit at least 5, 6 to 10, 11 to 15, and more than 15 years ago, respectively. This could translate to risk-adapted screening starting ages ranging from 53 (95% CI, 50-55) years to 67 (95% CI, 65-69) years, if current smokers begin screening at age 50. Conclusions and Relevance: This cohort study of the UK Biobank provides an empirical basis for risk-adapted starting ages for lung cancer screening among former heavy smokers.