Inverse association of eosinophil count with colorectal cancer incidence: Atherosclerosis Risk in Communities Study
Menée aux Etats-Unis, cette étude prospective de cohorte (10 675 participants) évalue l’effet protecteur d’un taux élevé d’éosinophiles, un marqueur de maladies allergiques, sur le risque de cancer colorectal
Background: Allergic conditions are associated with reduced risk of several malignancies. We hypothesized that blood eosinophil count, a marker for allergic disorders, is inversely associated with the risk of colorectal cancer (CRC) in the Atherosclerosis Risk in Communities (ARIC) prospective cohort. To our knowledge, the association between blood eosinophil count and cancer risk has not been investigated before. Methods: Relative eosinophil and total leukocyte counts were measured in blood at baseline. Absolute eosinophil counts were calculated by multiplying relative count by the total leukocyte count. Proportional hazards regression provided hazard ratios (HR) and 95% confidence intervals (CI) of CRC in relation to eosinophil count. Results: From 1987-2006, 242 incident CRC cases (187 colon; 56 rectal) occurred in 10,675 initially cancer-free participants. In a multivariate-adjusted model, HRs were 1.0, 0.70 (95%CI, 0.50;0.98) and 0.58 (95%CI, 0.40;0.83) across tertiles of absolute eosinophil count (P-trend=0.003). A similar inverse association was observed for relative eosinophil count. Age, sex, race, or smoking status did not modify associations. Conclusions and impact: We observed an inverse association between blood eosinophil count and CRC risk. This novel finding supports the hypothesis that allergies are protective for colorectal cancer, since an increased eosinophil count correlates with allergy in the developed world.