(HealthDay News) — People with both hay fever and asthma have a modestly reduced risk of dying from colorectal cancer, according to a study presented at the American Association for Cancer Research’s International Conference on Frontiers in Cancer Prevention Research, held from Oct. 16 to 19 in Anaheim, Calif.
Eric J. Jacobs, Ph.D., from the American Cancer Society in Atlanta, and colleagues assessed the correlation between having both hay fever and asthma and colorectal cancer mortality using data from 1,023,191 participants in the Cancer Prevention Study I (CPS-I), followed from 1959 to 1972, and 1,102,092 participants in CPS-II, followed from 1982 through 2008. Associations with the incidence of colorectal cancer were evaluated using data from 174,917 participants in the CPS-II Nutrition Cohort, a subgroup of CPS-II, followed from 1992 to 2007.
In CPS-I there were 5,644 colorectal cancer deaths during follow-up; in CPS-II there were 13,558 colorectal cancer deaths; and in the CPS-II Nutrition Cohort there were 3,365 incident colorectal cancers. The researchers found that, compared to having neither condition, having both asthma and hay fever correlated with a relative risk for colorectal mortality of 0.90 (95 percent confidence interval [CI], 0.74 to 1.09) in CPS-I; 0.79 (95 percent CI, 0.69 to 0.91) in CPS-II; and 0.83 (95 percent CI, 0.74 to 0.92) in a meta-analysis from both cohorts. In the CPS-II Nutrition Cohort, the relative risk for colorectal cancer incidence was 0.90 (95 percent CI, 0.71 to 1.14).
“If allergy-related immune responses are lowering colorectal cancer mortality in some individuals, that would imply that a similar kind of response might be inducible by a vaccine,” Jacobs said in a statement.