Impaired lung function and lung cancer risk in 461,183 healthy individuals: a cohort study

ABSTRACT Background It has been known that smoking and various lung diseases including lung cancer can cause lung function impairment. However, the impact of different types of lung function impairments, such as preserved ratio impaired spirometry (PRISm) and airflow obstruction (AO), on the incidence and mortality of lung cancer in both general and never-smoker populations remains unclear. We wished to examine the effect of lung function impairments on lung cancer risks. Methods This was a retrospective cohort study of individuals from a health surveillance program in Taiwan who underwent baseline spirometry tests at the entry point. PRISm was defined as an FEV1/FVC (Forced Expiratory Volume in 1 second/ Forced Vital Capacity) ratio >0.7 and FEV1 <0.8, while AO was defined as an FEV1/FVC ratio <0.7. Cox proportional hazards models and cubic spline curves were used to examine the associations between lung function impairments and lung cancer risks. Results The study included 461,183 individuals, of whom 14.3% had PRISm and 7.9% had AO. A total of 4,038 cases of lung cancer and 3,314 lung cancer-related deaths were identified during the 23 years of follow-up. Individuals with PRISm and AO exhibited a higher risk of lung cancer incidence and mortality compared to those with normal lung function. The adjusted hazard ratios (aHRs) and 95% confidence intervals (95%CI) were 1.14 (1.03-1.26) and 1.23 (1.10-1.37) in the overall cohort, and 1.08 (0.93-1.24), and 1.23 (1.05-1.45) in the never-smoker cohort. The risks of both developing and dying of lung cancer increased with the severity levels of lung function impairments and lower FEV1 values. Conclusion Impaired lung function is associated with increased risks of developing lung cancer and subsequent mortality. The study highlights the importance of considering lung function in lung cancer screening for better candidate selection. WHAT IS ALREADY KNOWN ON THIS TOPIC Impaired lung function is a common condition that can be observed in people with smoking habits and other respiratory illnesses including lung cancer. However, the effect of lung function impairment alone on the risks of lung cancer incidence and mortality is not clear. Early detection of lung cancer is essential for effective disease management, and lung cancer screening is a key preventive measure that can help achieve this. However, current lung cancer screening guidelines only consider age and smoking history, not lung function status. WHY THIS STUDY ADDS Impaired lung function is associated with an increased risk of lung cancer in a large Asian cohort. Nonetheless, among never-smoking individuals exhibiting spirometrically defined PRISM/AO, the observed risks were found to lack statistical significance, with the exception of lung cancer mortality within the non-smoking PRISm subgroup. HOW THIS STUDY MIGHT AFFECT RESEARCH, PRACTICE OR POLICY Lung function status should be taken into consideration in lung cancer screening criteria. The importance of monitoring and addressing lung function impairment in lung cancer risk management should also be widely shared with the medical community and the public.