Atopic allergic conditions and pancreatic cancer risk: Results from the Multiethnic Cohort Study.

Previous case-control studies have suggested that atopic allergic conditions (AACs) are inversely associated with pancreatic cancer, but this relationship has not been supported in many prospective settings. In this study, we investigated the influence of AACs (asthma, hay fever, or allergy) and the treatment of these conditions on pancreatic cancer risk among participants of the Multiethnic Cohort Study (MEC). AACs and antihistamine use were assessed via a baseline questionnaire when participants joined the MEC in 1993-1996. Risk ratios (RRs) and 95% confidence intervals (CIs) for pancreatic cancer incidence by AACs and antihistamines were calculated using Cox regression, adjusting for age, sex, ethnicity, education, smoking status, family history of pancreatic cancer, body mass index, diabetes, and alcohol intake. We further evaluated associations among subgroups defined by age, sex, ethnicity, follow-up time, and known pancreatic cancer risk factors. During an average 16-year follow-up, 1,455 incident cases of pancreatic cancer were identified among 187,226 white, African American, Latino, Japanese American, and Native Hawaiian men and women. AACs (RR 1.00, 95% CI 0.88-1.12) and antihistamines (RR 0.92, 95% CI 0.78-1.07) were not clearly associated with pancreatic cancer incidence. While these associations were also null for most subgroups, we did observe protective associations of AACs (RR 0.74, 95% CI 0.56-0.98) and antihistamines (RR 0.66, 95% CI 0.45-0.96) among the oldest participants (70+). Our results, in agreement with past prospective studies, suggest that AACs are not associated with pancreatic cancer in general, but the observed protective associations among the oldest age group may warrant future investigation.