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Quantitative Emphysema on Low-Dose Computed Tomography of the Chest and Risk of Lung Cancer and Airflow Obstruction: An analysis of the National Lung Screening Trial.
Pubmed ID
33326807 (View this publication on the PubMed website)
Digital Object Identifier
Chest. 2020 Dec 13

Labaki WW, Xia M, Murray S, Hatt CR, Al-Abcha A, Ferrera MC, Meldrum CA, Keith LA, Galbán CJ, Arenberg DA, Curtis JL, Martinez FJ, Kazerooni EA, Han MK


BACKGROUND: Lung cancer risk prediction models do not routinely incorporate imaging metrics available on low-dose computed tomography (LDCT) of the chest ordered for lung cancer screening.

RESEARCH QUESTION: What is the association between quantitative emphysema measured on LDCT and lung cancer incidence and mortality, all-cause mortality, and airflow obstruction in individuals who currently or formerly smoked undergoing lung cancer screening?

STUDY DESIGN AND METHODS: In 7,262 participants in the CT arm of the National Lung Screening Trial, % low attenuation area (%LAA) was defined as the percent of lung volume with voxels < -950 Hounsfield Units on the baseline exam. We built multivariable Cox proportional hazards models, adjusting for competing risks where appropriate, to test for association between %LAA and lung cancer incidence, lung cancer mortality and all-cause mortality with censoring at 6 years. We also built multivariable logistic regression models to test the cross-sectional association between %LAA and airflow obstruction on spirometry which was available in 2,700 participants.

RESULTS: The median %LAA was 0.8% (interquartile range: 0.2%-2.7%). Every 1% increase in %LAA was independently associated with higher hazards of lung cancer incidence (HR 1.02; 95% CI 1.01-1.03; p=0.004), lung cancer mortality (HR 1.02; 95% CI 1.00-1.05; p=0.045) and all-cause mortality (HR 1.01; 95% CI 1.00-1.03; p=0.042). Among participants with spirometry, 892 had airflow obstruction. The likelihood of airflow obstruction increased with every 1% increase in %LAA (OR=1.07; 95% CI 1.06-1.09; p<0.001). A %LAA cutoff of 1% had the best discriminative accuracy for airflow obstruction in participants older than 65 years.

INTERPRETATION: Quantitative emphysema measured on LDCT of the chest can be leveraged to improve lung cancer risk prediction and help diagnose COPD in individuals who currently or formerly smoked undergoing lung cancer screening.

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