Depression as a Risk of Lung Cancer in Women: a Nationwide Cohort Study

BACKGROUND: Lung cancer is a leading contributor to global cancer incidence and mortality. While depression has been linked to adverse health behaviors, particularly tobacco smoking, that may elevate cancer risk, the direct relationship between depression and lung cancer remains uncertain. We aimed to clarify this association in a large cohort of Korean women. METHODS: We analyzed data from the Korean National Health Information Database for women who completed the national health screening in 2012. A total of 2,032,241 participants aged 20 years or older were followed until December 2022. Depression was defined using insurance claims within the year preceding the baseline exam. Lung cancer cases were ascertained through matched health insurance and critical illness registration records. Adjusted hazard ratios (aHR) were calculated using multivariable Cox proportional hazards models. RESULTS: Over a mean follow-up of 9.3 years, 11,706 women developed lung cancer. Those with depression experienced higher incidence rates (1.02 per 1,000 person-years) and a modestly increased risk (aHR 1.09, 95% confidence interval [CI] 1.02-1.16) compared with women without depression. Stratified analyses indicated stronger associations among women aged 40-64 years (aHR 1.13, 95% CI 1.04-1.24), and former smokers (aHR 2.33, 95% CI 1.66-3.28)-particularly former smokers with at least 20 pack-years of smoking exposure (aHR 4.93, 95% CI 2.55-9.51). CONCLUSION: Depression was associated with elevated lung cancer risk in women, with effects modified by age and smoking history. Targeted interventions addressing mental health may contribute to lung cancer prevention, especially in susceptible subgroups.