Previous Lung Diseases and Lung Cancer Risk: A Systematic Review and Meta-Analysis

BackgroundIn order to review the epidemiologic evidence concerning previous lungdiseases as risk factors for lung cancer, a meta-analysis and systematic reviewwas conducted.
MethodsRelevant studies were identified through MEDLINE searches. Using randomeffects models, summary effects of specific previous conditions were evaluatedseparately and combined. Stratified analyses were conducted based on smokingstatus, gender, control sources and continent.
ResultsA previous history of COPD, chronic bronchitis or emphysema conferred relativerisks (RR) of 2.22 (95% confidence interval (CI): 1.66, 2.97) (from16 studies), 1.52 (95% CI: 1.25, 1.84) (from 23 studies) and 2.04 (95%CI: 1.72, 2.41) (from 20 studies), respectively, and for all these diseasescombined 1.80 (95% CI: 1.60, 2.11) (from 39 studies). The RR of lungcancer for subjects with a previous history of pneumonia was 1.43 (95%CI: 1.22–1.68) (from 22 studies) and for subjects with a previous historyof tuberculosis was 1.76 (95% CI = 1.49, 2.08),(from 30 studies). Effects were attenuated when restricting analysis to neversmokers only for COPD/emphysema/chronic bronchitis (RR = 1.22,0.97–1.53), however remained significant for pneumonia 1.36 (95%CI: 1.10, 1.69) (from 8 studies) and tuberculosis 1.90 (95% CI: 1.45,2.50) (from 11 studies).
ConclusionsPrevious lung diseases are associated with an increased risk of lung cancerwith the evidence among never smokers supporting a direct relationship betweenprevious lung diseases and lung cancer.