title: Risk factors shared by COPD and lung cancer and mediation effect of COPD: two center case-control studies.
abstract: OBJECTIVE
  To reveal the shared risk factors for chronic obstructive pulmonary disease (COPD) and lung cancer, and to analyze the mediation effect of COPD during lung carcinogenesis.
  
  
  METHODS
  We conducted four independent case-control studies included 1,511 COPD patients and 1,677 normal lung function controls and 1,559 lung cancer cases and 1,679 cancer-free controls during 2002-2011 in southern and eastern Chinese.
  
  
  RESULTS
  Eight factors were observed to be consistently associated with both diseases risk, including pre-existing tuberculosis, smoking, passive smoking, occupational exposure to metallic toxicant, poor housing ventilation, biomass burning, cured meat consumption, and seldom vegetables/fruits consumption. Furthermore, smoking and biomass burning conferred significantly higher risk effects on lung cancer in individuals with pre-existing COPD than those without. COPD also had significant mediation effects during lung carcinogenesis caused by smoking, passive smoking, and biomass burning, which explained about 12.0 % of effect, 3.8 % of effect, and 6.1 % of effect of these factors on lung tumorigenesis in turn.
  
  
  CONCLUSIONS
  Our study mapped a shared spectrum of etiological factors for both COPD and lung cancer in Chinese, and COPD acts as a mediator during lung cancer development. These observations should be in consideration for the prevention of both diseases.
authors.affiliation: The State Key Lab of Respiratory Disease, The Institute for Chemical Carcinogenesis, Collaborative Innovation Center for Environmental Toxicity, Guangzhou Medical University, 195 Dongfengxi Road, Guangzhou, 510182, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Yang
authors.forename: Xiaoxiao
authors.initials: X
authors.lastname: Lu
authors.forename: Jieqiong
authors.initials: J
authors.lastname: Deng
authors.forename: Yumin
authors.initials: Y
authors.lastname: Zhou
authors.forename: Dongsheng
authors.initials: D
authors.lastname: Huang
authors.forename: Fuman
authors.initials: F
authors.lastname: Qiu
authors.forename: Xiaorong
authors.initials: X
authors.lastname: Yang
authors.forename: Rongrong
authors.initials: R
authors.lastname: Yang
authors.forename: Wenxiang
authors.initials: W
authors.lastname: Fang
authors.forename: Pixin
authors.initials: P
authors.lastname: Ran
authors.forename: Nanshan
authors.initials: N
authors.lastname: Zhong
authors.forename: Yifeng
authors.initials: Y
authors.lastname: Zhou
authors.forename: Shenying
authors.initials: S
authors.lastname: Fang
authors.forename: Jiachun
authors.initials: J
authors.lastname: Lu
mesh_terms: D044466:Asian People; D016022:Case-Control Studies; D002681:China / Q000453:epidemiology; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000150:complications / Q000453:epidemiology* / Q000517:prevention & control; D008297:Male; D008875:Middle Aged; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications / Q000453:epidemiology* / Q000517:prevention & control; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects