Purposes: COPD is a well-known independent risk factor that is associated with primary lung cancer. There is, however, a striking paucity of women in studies demonstrating this association. The purpose of this study was to compare the prevalence of COPD as determined by pulmonary function tests (PFTs) between women and men at around the time of lung cancer diagnosis.
Methods: We retrospectively reviewed patients with newly diagnosed primary lung cancer who had undergone PFTs prior to their treatment. The diagnosis of airflow obstruction was made according to American Thoracic Society guidelines. Comparisons of the prevalence of COPD between men and women were performed using univariate and multivariate logistic regression analysis.
Results: Of the 294 patients in the study, 151 patients (51.4%) were men and 143 patient (48.6%) were women. Of the men, 110 patients (72.8%) had COPD compared with 75 patients (52.5%) among the women. This represented a significantly lower prevalence of COPD in women than in men (odds ratio [OR], 0.41; 95% confidence interval [CI], 0.25 to 0.67; p = 0.0003). When adjusted for age and smoking status, a sustained lower prevalence of COPD was noted in women compared to men (OR, 0.44; 95% CI, 0.26 to 0.74; p = 0.002). In a subset of 256 smokers, there remained a lower prevalence of COPD in women compared to men (OR, 0.45; 95% CI, 0.27 to 0.77; p = 0.003). Adjusted analysis to control for age and number of pack-years of smoking in this subset again showed a sustained reduction in the OR for women presenting with COPD (OR, 0.48; 95% CI, 0.28 to 0.83; p = 0.009).
Conclusions: When COPD was examined as an end point among patients who had newly diagnosed lung cancer, a significantly higher proportion of women had normal PFT results. Gender-based differences on PFT results should be considered during the screening of lung cancer, because the stratification of high-risk patients based on the presence of COPD may miss a significant proportion of women with lung cancer.