The correlation of emphysema or airway obstruction with the risk of lung cancer: a matched case-controlled study.

A matched case-controlled study was conducted to determine if airway obstruction or emphysema were associated with an increased risk of lung cancer. Lung cancer cases (n=24) were identified through a low-dose spiral computed tomography (CT) screening trial from 1,520 participants. Four controls without lung cancer were selected for each case from the participants and matched by sex, age and smoking history. Emphysema was assessed by quantitative CT analysis. Conditional logistic regression was employed to assess results of spirometry and CT quantitative analysis as potential risk factors for lung cancer. The likelihood of lung cancer was found to be significantly increased for those with forced expiratory volume in one second (FEV1) < or = 40% of predicted. The results suggested that a lower percentage of predicted FEV1 was indicative of lung cancer. No compelling evidence was found to suggest that the percentage of emphysema was associated with lung cancer. These results suggest an increased risk of lung cancer associated with airway obstruction. However, percentage of emphysema as determined by computed tomography was not associated with an increased risk of lung cancer.