Prior history of allergies and pancreatic cancer in the San Francisco Bay Area

Data from a large population-based case-control study conducted in the San Francisco Bay Area between 1994 and 2001 were analyzed to examine the association between pancreatic cancer and history of allergic conditions. Pancreatic cancer cases (n=532) had to be 21-85 years of age and were identified using rapid case ascertainment. Random digit dialing and Health Care Financing Administration lists (age, greater than or equal to65 years) were used to obtain 1,701 controls who were frequency-matched to cases by sex and age within 5 years. In-person interviews were conducted and detailed allergy history data were obtained for all participants. Prior history of any allergy was associated with a reduced risk estimate for pancreatic cancer (odds ratio (OR)=0.77, 95% confidence interval (CI): 0.63, 0.95). Inverse associations were observed for common allergens, including house dust (OR=0.72, 95% CI: 0.54, 0.94), cats (OR=0.59, 95% CI: 0.41, 0.85), plants (OR=0.77, 95% CI: 0.62, 0.96), and mold (OR=0.49, 95% CI: 0.32, 0.75), and for all allergic symptoms, although some confidence intervals included unity. Trends were observed for decreased risks associated with increasing number of allergies (p=0.0006) and severity of allergic symptoms (p=0.003). These results provide support for the plausibility that immune function in relation to allergies may play a role in the etiology of pancreatic cancer.