Smokeless and other noncigarette tobacco use and pancreatic cancer: a case-control study based on direct interviews

Cigarette smoking is an important and well-established cause of pancreatic cancer. In contrast, little is known about the effects of smoking cigars, pipes, and use of smokeless tobacco on pancreatic cancer risk. The objective of the present study was to examine the association between noncigarette tobacco use (i.e., cigars, pipes, smokeless tobacco) and pancreatic cancer risk among nonsmokers of cigarettes. A population-based case-control study of pancreatic cancer was conducted during 1986-1989 among residents of Atlanta, Georgia, Detroit, Michigan, and 10 counties in New Jersey. Direct interviews were successfully completed with 526 newly diagnosed pancreatic cancer patients and 2153 controls ages 30-79 years. This analysis was restricted to lifelong nonsmokers of cigarettes and based on interviews with 154 cases newly diagnosed with carcinoma of the exocrine pancreas and 844 population controls who reported no history of cigarette smoking. We observed a consistent pattern of increased risk associated with cigar smoking, although these elevations were not statistically significant. Participants who smoked cigars regularly (i.e., at least one cigar/week for >/=6 months) experienced a 70% increased risk [95% confidence interval (CI): 0.9-3.3], and those who never used other form of tobacco had a 90% increased risk (95% CI: 0.8-4.3). Risk was elevated among those who smoked more than one cigar/day [odds ratio (OR) = 1.8; 95% CI: 0.8-4.2) and among those who smoked cigars > 20 years (OR = 1.9; 95% CI: 0.9-3.9). Trends in risk with increasing amount and duration smoked were consistent but not statistically significant (P = 0.17 and P = 0.16, respectively). Subjects who used smokeless tobacco regularly had a 40% increased risk of pancreatic cancer (95% CI: 0.5-3.6) compared with nonusers of tobacco. We observed a marginally significant increasing risk with increased use of smokeless tobacco (P = 0.04); participants who used >2.5 oz of smokeless tobacco a week had an OR of 3.5 (95% CI: 1.1-11). Long-term use of smokeless tobacco (i.e., >20 years) was also associated with a nonsignificant increased risk (OR = 1.5; 95% CI: 0.6-4.0). In contrast, pipe smokers experienced no increased risk (OR = 0.6; 95% CI: 0.1-2.8). Our results suggest that heavy use of smokeless tobacco, and to a lesser extent, cigar smoking may increase the risk of pancreatic cancer among nonsmokers of cigarettes.