Abstract
BackgroundLung cancer and chronic obstructive pulmonary disease (COPD) share a common risk factor in cigarette smoking and a large portion of patients with lung cancer suffer from COPD synchronously. We therefore hypothesized that COPD is an independent risk factor for lung cancer. Our aim was to investigate the intrinsic linkage of COPD (or emphysema, chronic bronchitis and asthma) and lung cancer.MethodsThe present hospital-based case-control study included 1,069 patients with newly diagnosed lung cancer and 1,132 age frequency matched cancer-free controls. The odds ratios (ORs) for the associations between each previous pulmonary disease and lung cancer were estimated with logistic regression models, adjusting for age, sex, family history of cancer, BMI and pack year smoking. In meta-analysis, the pooled effects of previous pulmonary diseases were analyzed with random effects models; and stratification analyses were conducted on smoking status and ethnicity.ResultsIn the case-control study, previous COPD was associated with the odds for increased risk of lung cancer (OR = 1.29, 95% confidence interval [CI] = 1.00∼1.68); so were emphysema (OR = 1.55, 95%CI = 1.03∼2.32) and chronic bronchitis (OR = 1.22, 95%CI = 0.99∼1.67); while asthma was associated with odds for decreased risk of lung cancer (OR = 0.29, 95%CI = 0.16∼0.53). These associations were more pronounced in smokers (P<.05 for all strata), but not in non-smokers. In meta-analysis, 35 studies (22,010 cases and 44,438 controls) were identified. COPD was significantly associated with the odds for increased risk of lung cancer (pooled OR = 2.76; 95% CI = 1.85–4.11), so were emphysema (OR = 3.02; 95% CI = 2.41–3.79) and chronic bronchitis (OR = 1.88; 95% CI = 1.49–2.36); and these associations were more pronounced in smokers than in non-smokers (P<.001 respectively). No significant association was observed for asthma.ConclusionPrevious COPD could increase the risk of lung cancer, especially in smokers.
Highlights
Lung cancer and chronic obstructive pulmonary disease (COPD) are the leading causes of morbidity and mortality worldwide [1]
The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript
As COPD and other chronic pulmonary diseases such as emphysema, chronic bronchitis and asthma could be caused by inflammation in lung tissues, these conditions may act as intermediates or catalysts in the development of lung neoplasms or be related with lung cancer development through common etiologies and/or exposures [11,12]
Summary
Lung cancer and chronic obstructive pulmonary disease (COPD) are the leading causes of morbidity and mortality worldwide [1]. Lung cancer is the most frequent cancer and the leading cause of cancer related deaths [2]; its five-year survival rate is next to the lowest of all cancers [3].The chronic obstructive pulmonary disease (COPD) has been another major health problem all over the world with increasing incidence. As COPD and other chronic pulmonary diseases such as emphysema, chronic bronchitis and asthma could be caused by inflammation in lung tissues, these conditions may act as intermediates or catalysts in the development of lung neoplasms or be related with lung cancer development through common etiologies and/or exposures [11,12]. Our aim was to investigate the intrinsic linkage of COPD (or emphysema, chronic bronchitis and asthma) and lung cancer
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