Latency period of lung cancer in relation to tobacco smoking in Korea.

objectivesThis mixed-methods observational study aimed to examine the temporal relationship between trends in cigarette smoking prevalence and lung cancer mortality and incidence rates, and to estimate the latency period between smoking initiation and lung cancer diagnosis among smokers at the individual level.

methodsSmoking prevalence data for 1960-2022 were reconstructed using data from the Korea National Health and Nutrition Examination Survey (1998-2022). Lung cancer mortality data (1983-2022) and incidence data (1999-2022) were obtained from Statistics Korea and the Korea Central Cancer Registry. The population latency period was estimated using peak comparison and distributed lag non-linear models. The individual latency period was estimated as the average time interval between age at smoking initiation and age at lung cancer diagnosis using individual-level data from the National Health Insurance Service cohort.

resultsIn men, smoking prevalence peaked around 1985, whereas lung cancer mortality peaked around 2000 during 1960-2022, indicating a lag time of approximately 15 years. In women, lung cancer mortality peaked in 2002, while smoking prevalence peaked around the same time. The population-level latency period between smoking and lung cancer incidence was estimated to be 15 years after adjustment for age, gender, and year of outcome. The individual latency period was estimated to be 42.6 years (standard deviation [SD], 12.5) in men and 34.4 years (SD, 14.2) in women. Smoking intensity and age at initiation did not appear to shorten the individual latency period.

conclusionsEstimates of the smoking-attributable lung cancer burden should account for historical smoking prevalence from approximately 15 years earlier.