Increased mean lung density: Another independent predictor of lung cancer?
Objectives To investigate the relationship between emphysema phenotype, mean lung density (MLD), lung function and lung cancer by using an automated multiple feature analysis tool on thin-section computed tomography (CT) data. Methods Both emphysema phenotype and MLD evaluated by automated quantitative CT analysis were compared between outpatients and screening participants with lung cancer (n = 119) and controls (n = 989). Emphysema phenotype was defined by assessing features such as extent, distribution on core/peel of the lung and hole size. Adjusted multiple logistic regression models were used to evaluate independent associations of CT densitometric measurements and pulmonary function test (PFT) with lung cancer risk. Results No emphysema feature was associated with lung cancer. Lung cancer risk increased with decreasing values of forced expiratory volume in 1 s (FEV(ind 1)) independently of MLD (OR 5.37, 95% CI: 2.63-10.97 for FEV(ind 1) < 60% vs. FEV1 >= 90%), and with increasing MLD independently of FEV(ind 1) (OR 3.00, 95% CI: 1.60-5.63 for MLD > -823 vs. MLD < -857 Hounsfield units). Conclusion Emphysema per se was not associated with lung cancer whereas decreased FEV1 was confirmed as being a strong and independent risk factor. The cross-sectional association between increased MLD and lung cancer requires future validations.