Assessing the relationship between lung cancer risk and emphysema detected on low-dose CT of the chest.
BACKGROUND
Identification of risk factors for lung cancer can help in selecting patients who may benefit the most from smoking cessation interventions, early detection, or chemoprevention.


OBJECTIVE
To evaluate whether the presence of emphysema on low-radiation-dose CT (LDCT) of the chest is an independent risk factor for lung cancer.


METHODS
The study used data from a prospective cohort of 1,166 former and current smokers participating in a lung cancer screening study. All individuals underwent a baseline LDCT and spirometry followed by yearly repeat LDCT studies. The incidence density of lung cancer among patients with and without emphysema on LDCT was estimated. Stratified and multiple regression analyses were used to assess whether emphysema is an independent risk factor for lung cancer after adjusting for age, gender, smoking history, and the presence of airway obstruction on spirometry.


RESULTS
On univariate analysis, the incidence density of lung cancer among individuals with and without emphysema on LDCT was 25.0 per 1,000 person-years and 7.5 per 1,000 person-years, respectively (risk ratio [RR], 3.33; 95% confidence interval [CI], 1.41 to 7.85). Emphysema was also associated with increased risk of lung cancer when the analysis was limited to individuals without airway obstruction on spirometry (RR, 4.33; 95% CI, 1.04 to 18.16). Multivariate analysis showed that the presence of emphysema (RR, 2.51; 95% CI, 1.01 to 6.23) on LDCT but not airway obstruction (RR, 2.10; 95% CI, 0.79 to 5.58) was associated with increased risk of lung cancer after adjusting for potential cofounders.


CONCLUSIONS
Results suggest that the presence of emphysema on LDCT is an independent risk factor for lung cancer.
de Torres
Juan P
JP
Department of Respiratory Diseases, University Clinic of Navarra, University of Navarra, Navarra, Spain.
Bastarrika
Gorka
G
Wisnivesky
Juan P
JP
Alcaide
Ana B
AB
Campo
Arantza
A
Seijo
Luis M
LM
Pueyo
Jesús C
JC
Villanueva
Alberto
A
Lozano
María D
MD
Montes
Usua
U
Montuenga
Luis
L
Zulueta
Javier J
JJ
D000465:Algorithms; D005260:Female; D006801:Humans; D015994:Incidence; D008175:Lung Neoplasms / Q000000981:diagnostic imaging* / Q000453:epidemiology / Q000473:pathology; D008297:Male; D008875:Middle Aged; D016012:Poisson Distribution; D011446:Prospective Studies; D011656:Pulmonary Emphysema / Q000000981:diagnostic imaging* / Q000453:epidemiology / Q000473:pathology; D013902:Radiography, Thoracic; D012044:Regression Analysis; D012307:Risk Factors; D012907:Smoking / Q000453:epidemiology; D013030:Spain / Q000453:epidemiology; D013147:Spirometry; D011795:Surveys and Questionnaires; D014057:Tomography, X-Ray Computed