An increased risk of lung cancer in combined pulmonary fibrosis and emphysema patients with usual interstitial pneumonia compared with patients with idiopathic pulmonary fibrosis alone: a systematic review and meta-analysis

Background: Lung cancer is an important complication of combined pulmonary fibrosis and emphysema (CPFE). Whether the risk of lung cancer is higher in CPFE patients with usual interstitial pneumonia (UIP) than those with idiopathic pulmonary fibrosis (IPF) alone, remains controversial. We conducted this systematic review and meta-analysis to evaluate the prevalence of lung cancer in CPFE patients with UIP compared with IPF patients. Methods: We searched the PubMed, Embase, and Cochrane databases for studies that focused on the incidence of lung cancer in CPFE/UIP and IPF groups. We used a fixed-effects model to analyze the odds ratios (ORs) with 95% confidence intervals (CIs) according to data heterogeneity. The cumulative effects based on the publication year and sample size were assessed by cumulative meta-analysis. Results: A total of nine studies with 933 patients, including 374 CPFE patients with UIP, fulfilled the inclusion criteria. Overall, CPFE patients with UIP have a higher risk of lung cancer than those with IPF alone (OR = 2.69; 95% CI: 1.78-4.05). There were increased risks of lung cancer in CPFE/UIP patients with the presence of emphysema (OR = 2.93; 95% CI: 1.79-4.79) or emphysema in > 10% of the lung volume (OR = 2.22; 95% CI: 1.06-4.68). Conclusions: Our systematic review and meta-analysis indicated a significantly higher prevalence of lung cancer in CPFE patients with UIP than in patients with IPF alone. The reviews of this paper are available via the supplemental material section.