Background: An increased prevalence of allergies and an increased incidence of breast cancer have been observed. The hypothesis that atopy may have a protective effect against the risk of different types of breast cancer was evaluated.
Methods: In this study, 11,101 patients (11,101 women with a mean age of 55.2±14.7 years) with different types of breast cancer were tested for allergies. Allergies were confirmed based on the retrospective analysis of allergy diagnostic procedures in patients who had been previously diagnosed with breast cancer. The retrospective prevalence rates of active allergic diseases, including allergic rhinitis, bronchial asthma and atopic dermatitis, were assessed. All patients were also analyzed for bronchial asthma and allergic rhinitis according to the relevant guidelines. A group of healthy control patients was used for the comparisons.
Results: The women with breast cancer had a significantly lower incidence of IgE-mediated allergic diseases than the controls. The odds ratios (ORs) for allergic rhinitis, atopic dermatitis, and bronchial asthma were 0.61 (95% CI: 0.57-0.73), 0.17 (95% CI: 0.11-0.44), and 0.73 (95% CI: 0.65-0.83), respectively. The mean serum concentrations of total IgE were significantly lower in the study population of women with breast cancer than in the patients of the control group (39.2 ± 26.2 kU/L vs. 108.5 ± 38.5 kU/L; p = 0.002).
Conclusion: Our results suggest that the overall incidence of allergies, especially allergic rhinitis, is lower in patients with certain types of cancer than in individuals who did not have cancer. Further studies are needed to confirm our findings.