Prevalence and risk factors of lung nodules in a non-smoking Chinese population: A prospective study of low-dose computed tomography screening

Background: Low-dose computed tomography (LDCT) has significantly improved early detection of lung cancer, especially among high-risk populations. However, the risk factors and lung nodule distributions in non-smoking populations remain underexplored, particularly in Asia. Therefore, in this study, we aimed to explore the risk factors and delineate the detection rate, including lung nodule distributions discovered using LDCT, in a non-smoking Chinese population. Methods: This prospective, single-center study included asymptomatic adults who underwent LDCT screening at the National Cancer Center of China between January 2006 and December 2023. Lung nodules were defined as at least one non-calcified nodule, while clinically relevant lung nodules were defined as at least one solid or partially solid nodule, or at least one non-solid nodule. Multivariate logistic regression models were employed to identify risk factors associated with lung nodules. The outcomes included detection rates and distribution of both nodule types. Results: Of 23,271 participants, lung nodules were detected in 40.1% (9,342/23,271); 4.3% (1,012/23,271) had clinically relevant lung nodules. Risk factors for lung nodule development included female sex (odds ratio [OR] 1.12, 95% confidence interval [CI] 1.06–1.19), second-hand smoke (SHS) exposure (OR 1.59, 95% CI 1.49–1.70), and emphysema (OR 1.49, 95% CI 1.24–1.78). The incidence of lung nodules increased with age, peaking at 70–74 years (OR 3.10, 95% CI 2.53–3.79). Risk factors for clinically relevant lung nodules included increasing age, SHS exposure (OR 1.44, 95% CI 1.22–1.69), and emphysema (OR 1.84, 95% CI 1.36–2.49). Detection rates for both nodule types were positively correlated with age (lung nodules: women 33.7–61.4%, men 32.3–57.5%; clinically relevant lung nodules: women 2.4–12.4%, men 2.2–15.1%). Conclusions: This real-world study of a non-smoking Chinese population revealed high lung nodule detection rates, with women exhibiting a higher detection rate than men. SHS has emerged as a significant risk factor for both lung and clinically relevant nodules. These findings highlight the importance of refining LDCT screening strategies and risk models for non-smoking populations in Asia.