How Can Lung Cancer Screening Improve Early Detection of COPD?

Lung cancer screening (LCS) by low-dose computed tomography (LDCT) does not examine spirometry in eligible patients, but study findings published this week in the Annals of the American Thoracic Society suggest that adding this feature could improve the high burden of undiagnosed chronic obstructive pulmonary disease (COPD) and emphysema.

Based on prior trial findings, LCS by LDCT has been found to significantly reduce the relative risk of lung cancer-specific and all-cause mortality by 20.0% and 6.7%. When it comes to eligibility, those who undergo LCS are typically of older age or former smokers, which are 2 of the strongest predictors of the development of COPD.

The researchers noted that in prior LCS studies, prevalence rates of COPD have reached as high as 38%; a figure nearly 4 times higher than the general population. This notable figure highlights the frequency of undiagnosed COPD in at-risk patients who may be asymptomatic.

The study authors sought to explore the clinical significance of COPD and emphysema detected at LCS. They examined associations between symptoms, comorbidities, spirometry, and emphysema in participants enrolled in the Lung Screen Uptake Trial.

The cross-sectional study included 60- to 75-year-old smokers and ex-smokers (n = 986) who adhered to a “lung health check” between November 2015 and July 2017. Participants offered LDCT included those with a smoking history greater than 30 pack-years and who quit less than 15 years ago, or those who met a lung cancer risk greater than 1.51% via the Prostate Lung Colorectal Ovarian model or greater than 2.50% via the Liverpool Lung Project model.

After undergoing the LDCT, 560 (57%) participants exhibited prebronchodilator spirometry consistent with COPD. Notably, 67% of these participants did not have a prior history of COPD and were termed undiagnosed. In patients with a prior history of COPD, emphysema was prevalent in 73%, with prevalence rates also high in those undiagnosed (68%).

For participants with known COPD as opposed to those undiagnosed, inhaler use and symptoms were more common (63% vs 33% with persistent cough, P = .001; 73% vs 33% with dyspnea, P = .001). Additionally, airflow limitation was indicated as a stronger predictor for respiratory symptoms than emphysema.

“There is high burden of undiagnosed COPD and emphysema in LCS participants. Adding spirometry findings to the LDCT enhances identification of individuals with COPD,” wrote the study authors.

In concluding, the researchers noted that they plan to expand their studies to a larger cohort to evaluate the impact of early detection of airflow limitation and emphysema through LCS on behavior change and long-term COPD outcomes.

Reference

Ruparel M, Quaife SL, Dickson JL, et al. Prevalence, symptom burden, and underdiagnosis of chronic obstructive pulmonary disease in a lung cancer screening cohort. Ann Am Thorac Soc. Published online July 1, 2020. doi:10.1513/AnnalsATS.201911-857OC