Exercise intensity and all-cause mortality among individuals with and without lung cancer: a nationwide propensity score-matched cohort study

Objective Lung cancer is associated with high mortality, and emerging evidence suggests that physical activity may improve survival outcomes. However, the influence of exercise intensity on all-cause mortality among individuals with lung cancer compared with a matched non-cancer comparison cohort remains unclear. This study examined the association between exercise intensity and mortality in a large, propensity score–matched cohort of Korean adults with and without lung cancer. Methods We conducted a nationwide retrospective cohort study using data from the Korean National Health Insurance Service. Of 1,134,909 individuals in the source cohort, the final propensity score–matched analytic cohort included 7,296 participants: 3,648 individuals with lung cancer and 3,648 J00 non-cancer comparison participants. Associations between exercise intensity and all-cause mortality were assessed using multivariable Cox proportional hazards regression, adjusting for measured demographic, behavioral, laboratory, and comorbidity-related covariates. Survival differences according to lung cancer status and exercise intensity were examined using Kaplan–Meier analysis. Results Reporting vigorous-intensity activity on at least one day per week was associated with a lower hazard of all-cause mortality compared with reporting no moderate- or vigorous-intensity activity. In multivariable Cox proportional hazards analysis, any reported vigorous-intensity activity was associated with a lower hazard of death (HR = 0.734, 95% CI: 0.666–0.809; p < 0.0001) after adjustment for measured demographic, behavioral, laboratory, and comorbidity-related covariates. Higher CCI was also associated with increased mortality risk. Conclusions Self-reported activity category was associated with all-cause mortality in this matched nationwide cohort. However, because the primary analysis was conducted in the overall matched cohort and cancer stage, histological subtype, treatment modality, and performance status were unavailable, residual confounding and reverse causation cannot be excluded. These findings should be interpreted as observational associations rather than lung cancer-specific or causal effects. Prospective studies incorporating detailed cancer-specific clinical information and more comprehensive physical activity assessment are warranted.