Impact of <scp>COPD</scp> and emphysema on survival of patients with lung cancer: A meta‐analysis of observational studies

<jats:title>Abstract</jats:title><jats:p>Both <jats:styled-content style="fixed-case">COPD</jats:styled-content> and emphysema are associated with an increased incidence of lung cancer, but the impacts of these comorbidities on lung cancer prognosis are still unclear. Herein, we conducted a meta‐analysis to clarify whether the presence of these comorbidities indicates poor survival in patients with lung cancer. A comprehensive search was conducted using PubMed, Embase, Web of Science, <jats:styled-content style="fixed-case">ASCO</jats:styled-content> Abstracts and Cochrane library for articles published before 1 <jats:styled-content style="fixed-case">J</jats:styled-content>une 2015. Papers referenced by the obtained articles were also reviewed. Main outcomes were overall survival (<jats:styled-content style="fixed-case">OS</jats:styled-content>) and disease‐free survival (<jats:styled-content style="fixed-case">DFS</jats:styled-content>) in patients with lung cancer. Pooled hazard ratio (<jats:styled-content style="fixed-case">HR</jats:styled-content>) and 95% confidence intervals (<jats:styled-content style="fixed-case">CI</jats:styled-content>s) were calculated using random‐effects models. Subgroup and sensitivity analyses were also conducted. Of 58 full texts reviewed, 26 met our inclusion criteria that were derived from 21 and seven studies examining the impacts of <jats:styled-content style="fixed-case">COPD</jats:styled-content> and emphysema on survival of lung cancer, respectively. Meta‐analyses revealed that concomitant <jats:styled-content style="fixed-case">COPD</jats:styled-content> was associated with poorer <jats:styled-content style="fixed-case">OS</jats:styled-content> (<jats:styled-content style="fixed-case">HR</jats:styled-content>, 1.17; 95% <jats:styled-content style="fixed-case">CI</jats:styled-content>: 1.10–1.25, <jats:italic>n</jats:italic> = 20), which was independent of tumour staging, diagnostic criteria of <jats:styled-content style="fixed-case">COPD</jats:styled-content> or location, and <jats:styled-content style="fixed-case">DFS</jats:styled-content> (<jats:styled-content style="fixed-case">HR</jats:styled-content>, 1.52; 95% <jats:styled-content style="fixed-case">CI</jats:styled-content>: 1.04–2.23, <jats:italic>n</jats:italic> = 6) with high heterogeneity (<jats:styled-content style="fixed-case">I</jats:styled-content><jats:sup>2</jats:sup> = 78%). The presence of emphysema in patients with lung cancer predicted worse <jats:styled-content style="fixed-case">OS</jats:styled-content> (<jats:styled-content style="fixed-case">HR</jats:styled-content>, 1.66; 95% <jats:styled-content style="fixed-case">CI</jats:styled-content>: 1.25–2.22, <jats:italic>n</jats:italic> = 7), but not poorer <jats:styled-content style="fixed-case">DFS</jats:styled-content>. The presence of <jats:styled-content style="fixed-case">COPD</jats:styled-content> and emphysema are robust predictors of poor survival in patients with lung cancer. Early detection of these diseases should be taken into account for lung cancer surveillance and management.</jats:p>