title: Association between chronic obstructive pulmonary disease and lung cancer: the missing link.
abstract: OBJECTIVE
  This review focuses on current knowledge of specific processes that drive chronic airway inflammation which are important in the pathogenesis of both chronic obstructive pulmonary disease (COPD) and lung cancer.
  
  
  METHODS
  The data used in this review were obtained mainly from studies reported in the PubMed database (1997 - 2012) using the terms of COPD and lung cancer.
  
  
  METHODS
  Data from published articles about prevalence of COPD-lung cancer overlap and mechanism involved in lung cancer development in COPD were identified, retrieved and reviewed.
  
  
  RESULTS
  COPD prevalence, morbidity and mortality vary and are directly related to the prevalence of tobacco smoking except in developing countries where air pollution resulting from the burning of biomass fuels is also important. COPD is characterized by a chronic inflammation of lower airway and, importantly, the presence of COPD increases the risk of lung cancer up to 4.5 fold among long-term smokers. COPD is by far the greatest risk factor for lung cancer amongst smokers and is found in 50% - 90% of patients with lung cancer.
  
  
  CONCLUSIONS
  Both COPD and lung cancer are tobacco smoking-associated chronic diseases that cluster in families and aggravate with age, and 50% - 70% of patients diagnosed with lung cancer have declined spirometric evidence of COPD. Understanding and targeting common pathogenic mechanisms for lung cancer and COPD would have potential diagnostic and therapeutic implications for patients with these lung diseases and for people at risk.
authors.affiliation: Department of Respiratory Medicine, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China. wangzengli@tom.com
authors.forename: Zeng-li
authors.initials: ZL
authors.lastname: Wang
mesh_terms: D005541:Forced Expiratory Volume; D059647:Gene-Environment Interaction; D006801:Humans; D007249:Inflammation / Q000150:complications; D008175:Lung Neoplasms / Q000453:epidemiology / Q000209:etiology*; D015995:Prevalence; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications* / Q000453:epidemiology; D012907:Smoking / Q000009:adverse effects