Eosinophilia in routine blood samples as a biomarker for solid tumor development - A study based on the Copenhagen Primary Care Differential Count (CopDiff) Database.

AbstractBackground. Eosinophilia may represent an early paraclinical sign of malignant disease and a host anti-tumor effect. The association between eosinophilia and the development of solid tumors has never before been examined in an epidemiological setting. The aim of the present study was to investigate eosinophilia in routine blood samples as a potential biomarker of solid tumor development in a prospective design.Material and methods. From the Copenhagen Primary Care Differential Count (CopDiff) Database, we identified 356 196 individuals with at least one differential cell count (DIFF) encompassing the eosinophil count during 2000–2007. From these, one DIFF was randomly chosen and categorized according to no (< 0.5 × 109/l), mild (≥ 0.5–1.0 × 109/l) or severe (≥ 1.0 × 109/l) eosinophilia. From the Danish Civil Registration System and the Danish Cancer Registry we ascertained all-cause death and solid tumors within the first three years following the DIFF. Using multivariable logistic regression, odd...