Number of Eosinophils and Incidence of Cancer in a Japanese Population : A Single Institution Study

抄録

Objective : Allergies might be associated with a low risk of developing malignant diseases. When an allergy is present, it is thought that the immune surveillance mechanism may inhibit carcinogenesis because the immune system is in a state of hyperreactivity. Usually, eosinophils increase in this state. Therefore, we investigated an association between the number of eosinophils and cancer incidence.

Methods: This cross-sectional study included 31,350 Japanese individuals, and was conducted at the Center for Preventive medicine, NTT Medical Center Tokyo, from 2006 to 2011. Associations of the number of eosinophils with cancer were assessed based on cancer-related information from self-reported medical histories in questionnaires. Absolute eosinophil counts were calculated by multiplying the relative count by the total WBC count.

Results: Among all 31,350 subjects, the mean absolute eosinophil count was 145.8/μL, 21% had allergies and 4.9% had cancer. The incidence of cancers was significantly lower in a group with eosinophil counts >350/μL than in those with eosinophil counts≤350/μL (3.75% vs 4.95%, p=0.03). Multivariate analysis revealed that allergies and eosinophils >350/μL were independent negative factors for cancer (p<0.0001, p=0.012, respectively).

Conclusions: An increased number of eosinophils was significantly associated with low incidence of cancers. In addition, our results suggested that high eosinophil counts may be inversely associated with cancer risk, regardless of whether allergies are present or not.