Passive smoking and the use of noncigarette tobacco products in association with risk for pancreatic cancer: a case-control study.

Pancreatic cancer is the fourth leading cause of cancer-related deaths for both men and women in the United States. It has been estimated that, in 2006, about 33,730 Americans will be diagnosed with pancreatic cancer and that 32,300 will die of the disease. The etiology of pancreatic cancer remains perplexing, and few risk factors have been identified clearly.1 It has been demonstrated that cigarette smoking is responsible for approximately 25% of pancreatic cancer cases.2-5 Other factors, such as diet, history of chronic pancreatitis, diabetes, family history of pancreatic cancer, and some hereditary conditions, also may contribute to the development of this deadly disease.6-11 Smoking prevalence in the United States has declined since 1997; however, despite the over-whelming evidence of the harmful effects of smoking, almost 22% of adults in the United States still smoked cigarettes in 2003.12,13 This prevalence of smoking may have disproportionately widespread implications. During smoking of cigarettes, cigars, pipes, and other tobacco products, not only is mainstream smoke drawn and inhaled by the smokers, but a sidestream of smoke also is released into the air. Once released, this sidestream smoke is mixed with exhaled mainstream smoke; together, they make up secondhand tobacco smoke, also referred to as involuntary, environmental, or passive smoking, to which both smokers and nonsmokers are exposed.14 A recent report indicated that almost 60% of children in the United States ever are exposed to secondhand tobacco smoke. However, the proportion of nonsmokers with detectable cotinine levels, a marker of passive smoking, declined from 88% in 1988 to 1991 to 43% in 2001 to 2002. The greatest prevalence of exposure was reported among African Americans.15 Previous studies demonstrated that passive smoking is associated positively with an increased risk for lung cancer and breast cancers.16-19 The relation between passive smoking and pancreatic cancer previously had been investigated in only 1 study.20 A weak but nonsignificant association between passive smoking and the risk of pancreatic cancer was observed among never smokers (odds ratio [OR], 1.21, 95% confidence interval [95% CI], 0.60-2.44), and passive smoking also was identified as a confounder for the risk of pancreatic cancer associated with active smoking. In addition to cigarette smoking, noncigarette tobacco use has been increasing in the United States.21 Several previous studies have reported significant associations between the use of pipes, 22 smokeless tobacco, 23 or cigars24,25 and the risk of pancreatic cancer. Because of the high prevalence of cigarette smoking among patients with pancreatic cancer, studies of passive smoking or of the use of noncigarette tobacco products often are limited by the small number of exposed individuals among never smokers. To further assess the associations between the risk of pancreatic cancer and passive smoking and the use of other tobacco products, we conducted a large-scale case-control study from 2000 to 2006. The current report includes findings on the relation between pancreatic cancer and smoking cigarettes, cigars, and pipes; the use of smokeless tobacco products; and passive smoking after controlling for the confounding effects of other confounders and major risk factors for this disease.