Previous studies have provided suggestive evidence of an inverse association between atopic allergic conditions (AAC) and colorectal cancer (CRC) incidence and mortality in predominantly White populations. Here we examined the association between AAC and CRC among White, African American, Native Hawaiian, Japanese American, and Latino men and women in the Multiethnic Cohort (MEC). AAC exposure status was ascertained via self-reported physician diagnosis using a baseline 26-page validated questionnaire. The analysis included 4259 incident CRC cases and 1221 CRC-related deaths ascertained between 1993 and 2010. We also examined associations by ethnic group, location, and stage of cancer as well as potential effect modification by CRC risk factors. AAC was associated with a reduced risk of colorectal cancer incidence among both men and women (RR = 0.85, 95% CI 0.79, 0.91, p < 0.0001). The reduction in risk was noted in each population and was significant in Whites (RR = 0.84, 95% CI 0.71, 0.98, p = 0.03), African Americans (RR = 0.81, 95% CI 0.69, 0.95, p = 0.01), and Japanese Americans (RR = 0.85, 95% CI 0.75, 0.97, p = 0.01). Suggestive evidence of effect modification was noted by smoking (p = 0.07) and aspirin use (p = 0.08), with a greater protective effect observed among current smokers (RR = 0.72, 95% CI 0.58, 0.89, p = 0.002) and never users of aspirin (RR = 0.81, 95% CI 0.73, 0.89, p < 0.0001). Individuals with AAC also had a 19% reduction in CRC-related mortality (P = 0.004). Colonoscopy screening is unlikely to explain these inverse associations, as individuals with AAC were more likely to be screened than those without AAC (p < 0.003 for all ethnic groups). These findings provide support for an association between immune pathology and colorectal cancer, potentially through modulation of the immune system's IgE-mediated pathways systemically and within the gut.

Citation Format: Neal A. Tambe, Dan O. Stram, Lynne R. Wilkens, Peggy Wan, Frank D. Gilliland, Brian E. Henderson, Loic Le Marchand, Christopher A. Haiman. Atopic allergic conditions and colorectal cancer risk in the Multiethnic Cohort. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr LB-261. doi:10.1158/1538-7445.AM2014-LB-261