Prognostic significance of CD24 and CD44 in breast cancer: a meta-analysis

Objective: Numerous studies have focused on the prognostic roles of CD24 and CD44 in breast cancer, but the results have been equivocal. The aim of this study was to gain better insight into the relationship between expression of CD24 and of CD44, either alone or in combination, and prognostic parameters in breast cancer. Methods: Publications addressing the associations of CD24 or CD44 expression with survival outcome in breast cancer were selected for the meta-analysis according to defined criteria. Studies were pooled and odds ratios (ORs) or hazard ratios (HRs) were calculated. Publication bias and sensitivity analyses were also conducted. Results: Sixteen studies comprising 5,697 breast cancer cases were included in our meta-analysis. Overall, CD24 overexpression was significantly associated with histological grade (OR = 1.52; 95% CI 1.12-2.06, p = 0.007), stage (OR = 1.74; 95% CI 1.27-2.40, p<0.001), shortened overall survival (HR = 1.48; 95% CI 1.21-1.80, p<0.001) and disease- free survival (HR 1.45, 95% CI 1.19-1.76, p<0.001), while no such association was observed when we limited our analysis to CD44 and CD44+/CD24-phenotypes. Subgroup analyses for CD24 according to the studies categorized by ethnicity, staining patterns and follow-up period were also conducted, and supported the stability of the prognostic role of CD24. Conclusions: Our study demonstrated that the putative stem cell marker CD24 was significantly associated with worse survival based on the obtained data. In particular, CD24 may play a role in tumorigenesis and cancer progression. However, further large-scale studies are needed to confirm these findings.