Environmental tobacco smoke and pancreatic cancer: a case-control study.

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.