title: Environmental tobacco smoke and pancreatic cancer: a case-control study.
abstract: BACKGROUND
  It has been conformed that active smoking is an established risk factor for pancreatic cancer, but the role of environmental tobacco smok (passive smoking) in pancreatic cancer remains unclear. We intended to study the relationship between passive smoking and pancreatic cancer.
  
  
  METHODS
  From Oct. 1991 to Sep. 2014, A hospital-based case-control study on pancreatic cancer was conducted from the inpatient of five hospitals. 1076 cases pancreatic cancer patients. History of exposure to environmental tobacco smoke was assessed through questionnaires. Relative risks (RR) and 95% confidence intervals (CI) were estimated using Cox proportional hazards models.
  
  
  RESULTS
  During 23 years of follow-up (1991-2014), 1076 patients were diagnosed with pancreatic cancer (686 men and 390 women). Compared to paternal smoking (RR, 0.97; 95% CI, 0.77-1.21; P = 0.084), maternal smoking significantly increased the risk of pancreatic cancer (R, 1.56; 95% CI, 1.13-1.98; P = 0.018). Although the risk associated with maternal smoking remained elevated compared to the never smokers (RR, 1.49; 95% CI, 1.07-2.27), there was no statistical significance.
  
  
  CONCLUSIONS
  The positive association with maternal smoking suggests that environmental tobacco smoke, potentially in utero or in early life, may be associated with pancreatic cancer.
authors.affiliation: Department of Surgical Oncology, Linyi Cancer Hospital Linyi, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Ding
authors.affiliation: Department of Laboratory, Women and Children's Hospital of Qingdao Qingdao, Shandong, China.
authors.forename: Chundong
authors.initials: C
authors.lastname: Yu
authors.affiliation: Department of Dialysis Room, Zhangqiu Hospital of traditional Chinese Medicine Zhangqiu, Jinan, China.
authors.forename: Zenggang
authors.initials: Z
authors.lastname: Han
authors.affiliation: Department of Neurology, People's Hospital of Zhangqiu Jinan, China.
authors.forename: Sunyu
authors.initials: S
authors.lastname: Xu
authors.affiliation: Department of Surgical Oncology, Qilu Hospital Jinan, China.
authors.forename: Dacheng
authors.initials: D
authors.lastname: Li
authors.affiliation: Department of Oncology, People's Hospital of Henan Zhengzhou, China.
authors.forename: Xiao
authors.initials: X
authors.lastname: Meng
authors.affiliation: Department of General Surgery, The Affiliated Hospital of Qingdao University Qingdao, China.
authors.forename: Dong
authors.initials: D
authors.lastname: Chen
keywords: Pancreatic cancer; case-control study; smoking