1. In a retrospective review of over 190 patients with primary lung cancers, patients with lower grade emphysema and airway-predominant disease as determined by pulmonary computed tomography had a significantly higher frequency of central lung cancers as compared to patients with severe emphysema.
Evidence Rating Level: 3 (Average)
Study Rundown: Chronic obstructive pulmonary disease (COPD) is a progressive condition characterized by both chronic bronchitis, or abnormal small airway inflammatory response, and emphysema, the parenchymal destruction of alveoli. COPD is directly related to smoking exposure and subsequently, lung carcinogenesis. However, there has been a paucity of data regarding the relationship between emphysema severity and the anatomical location of primary lung cancers in affected patients. This retrospective review analyzed over 190 lung cancer patients with COPD for tumor location and emphysema severity as assed by pulmonary CT imaging. At the conclusion of the trial, lower emphysema grades (0-2) were associated with a four-fold greater risk of centrally located lung tumors as compared to patients with severe emphysema (grade 4). This association remained after adjusting for age, smoking extent, and performance on spirometry. The results of this article support the hypothesis that COPD is a heterogeneous disease with varying spectrum of small-airway destruction and that emphysema severity may preferentially affect distal airways leading to peripheral lung cancer. The results also support the increased use of thin-section screening CT, bronchoscopy or sputum cytology for a subset of patients with lower-grade emphysema given its increased sensitivity for central lung cancers. The study is limited by the relatively small sample size and the retrospective study design. Additional large prospective trials are needed to confirm this association, and to determine if the suggested additional screening methodologies may reduce the time-to-diagnosis in these patients.
In-Depth [retrospective review]: In this retrospective study, the graded severity of emphysema was compared to the location of known lung cancers in patients with or without concurrent COPD. The study analyzed 405 patients with pathologically proven primary lung cancer from two academic hospitals in South Korea from 2010 to 2014. Patients with pulmonary fibrosis were excluded given their independent risk factor for peripheral lung cancers. Of the 405 included patients, 198 had COPD and 207 did not have COPD. Each group’s respective mean age was 67.6±7.1 and 63.6±10.4, and the COPD group was predominantly male at 96.5%, while the group without COPD was only 47.3% male. Grading of emphysema on CT was performed by two independent readers according to the criteria delineated by the National Emphysema Treatment Trial. Two additional, blinded readers determined if tumors were peripherally or centrally located. At the conclusion of the trial, patients with COPD had a significantly higher risk of central lung cancer as compared to non-COPD patients (36.4% vs. 17.4%; p< 0.001). However, in patients with COPD, lower emphysema grades were negatively associated with central location (OR: 0.69; 95% CI: 0.51-0.93; p = 0.016). This association remained after multivariate regression adjustments for age, smoking, and spirometry results.
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