Influence of the type of emphysema in the relationship between COPD and lung cancer

There are no studies analyzing the relationship between emphysema and lung cancer (LC). With this aim and in order to make some comparisons between different clinical variables, we carried out the present study.

This is a case-control study, patients with COPD and LC being the cases and subjects with stable COPD being the controls. Clinical and functional parameters, as well as the existence of radiological emphysema, were evaluated in a qualitative and quantitative way, using a radiological density of -950 Hounsfield units as a cutoff point in the images. The existence of several different types of emphysema (centrilobular, paraseptal, panacinar, or bullae) was analyzed, allowing patients to have more than one simultaneously. The extent to which lobes were involved was evaluated and the extension of emphysema was graduated for each type and location, following a quantitative scale. Differences between cases and controls were compared by using bivariate and multivariate analyzes with results expressed as OR and 95% CI.

We included 169 cases and 74 controls, 84% men with a FEV₁ (%) of 61.7±18.5, with 90.1% non-exacerbators. Most of them (50%) were active smokers and 47.2% were ex-smokers. Emphysema was found in 80.2% of the subjects, the most frequent type being centrilobular (34.4%). The only significantly different factor was the presence of paraseptal emphysema (alone or combined; OR =2.2 [95% CI =1.1-4.3, P = 0.03]), with adenocarcinoma being significantly more frequent in paraseptal emphysema with respect to other types (67.2% vs 32.8%, P =0.03).

Patients with COPD and paraseptal emphysema could be a risk group for the development of LC, especially adenocarcinoma subtype.