Background: In breast cancer, the expression of CD24 represents a poorly recognised unfavourable prognostic factor. CD24 has been described to be potentially down-regulated by estrogen receptor alpha (ER). The present study was aimed at examining the predictive value of CD24 expression in tamoxifen-treated breast cancer cases.
Materials and methods: Sixty patients with primary invasive ductal breast cancers with post-operative tamoxifen treatment were enrolled in the study. Immmunohistochemical reactions were performed using monoclonal antibodies directed against CD24 and ER.
Results: Cases demonstrating cytoplasmic-membranous expression of CD24 (CD24c-m) proved to be characterised by a significantly lower expression of ER as compared to CD24c-m-negative cases. A multivariate progression analysis based on the Cox proportional hazard model demonstrated that CD24c-m expression is an independent prognostic factor for poor overall survival.
Conclusion: The data from the present study suggested that CD24c-m expression is specific for tamoxifen-resistant breast cancer cases. CD24 should be subjected to comprehensive studies as a marker of resistance to tamoxifen treatment.