The association of atopic diseases with breast, prostate, and colorectal cancers: a meta-analysis

There is a long-standing interest in finding whether allergic disorders cause or prevent cancer. We meta-analyzed associations of allergies with prostate, breast, and colorectal cancers. We searched MEDLINE, EMBASE, and Web of Science between 1966 and 2008 and eligible reference lists. A total of 16 observational studies were included. Meta-analyses revealed no evidence that asthma, hay fever, or ‘any allergy’ are associated with cancers of the breast (relative risk, RR = 0.93, 95% CI: 0.73–1.19 for asthma; 1.04, 0.94–1.16 for hay fever; 1.01, 0.94–1.08 for any allergy); prostate (RR = 0.93, 95% CI: 0.76–1.15 for asthma; 0.96, 0.87–1.05 for hay fever; 1.01, 0.87–1.17 for any allergy); or colorectum (RR = 0.95, 95% CI: 0.77–1.16 for asthma; 0.95, 0.86–1.05 for hay fever; 0.94, 0.85–1.04 for any allergy). There was a positive association of atopy (assessed by allergen-specific IgE or skin prick testing) with prostate cancer (RR = 1.43, 95% CI: 1.08–1.91), but not breast (1.18, 0.90–1.55) or colorectal (1.32, 0.69–2.53) cancers. There is little epidemiological support for the immune surveillance theory or antigenic stimulation theory in breast or colorectal carcinogenesis. The findings for prostate cancer warrant further investigation.