Blood eosinophilic relative count is prognostic for breast cancer and associated with the presence of tumor at diagnosis and at time of relapse

Abstract

Background Cancer outcome is associated with circulating immune cells, including eosinophils. Here we analyze the relative eosinophil count (REC) in different breast cancer subtypes. Methods Stage I–III breast cancer patients were included in the study and classified as REC-high vs low (cutoff 1.5%) or relative lymphocyte count (RLC)-high vs low (cutoff 17.5%). The co-primary endpoints were the breast cancer-specific survival (BCSS) or the time to treatment failure (TTF) in the REC groups. Results Overall 930 patients were included in the study. We observed a benefit for REC-high vs REC-low in TTF (HR 0.610, 95% CI 0.458–0.812), and in BCSS (HR 0.632, 95% CI 0.433–0.923). Similarly, we observed a better TTF (HR 0.421, 95% CI 0.262–0.677) and BCSS (HR 0.350, 95% CI 0.200–0.614) in RLC-high vs low. A lower relapse rate was observed in the REC-high vs REC-low group (17.1% vs 24.7%, p = 0.005), not confirmed in the multivariate analysis. A lower median REC at baseline and at relapse was observed compared to REC after surgery and during cancer-free follow-up (p < .0001). Conclusions REC could be a new promising, affordable and accessible predictive and prognostic biomarker in all breast cancer subtypes.

Keywords

• eosinophil
• breast cancer
• immune system
• immune biomarker
• lymphocyte