Expression of CD44 and the survival in glioma: a meta-analysis

Background: Higher tumor expression of CD44, a marker of cancer stem cells (CSCs), is associated with poor overall survival (OS) in various cancers. However, the association between CD44 and poor OS remains inconsistent in glioma. We aimed to evaluate the potential predictive role of CD44 for prognosis of glioma patients in a meta-analysis. Methods: Observational studies comparing OS of glioma patients according to the level of CD44 were identified through searching PubMed, Embase, and Cochrane's Library databases. Meta-analyses were performed with a random- or fixed-effect model according to the heterogeneity. Subgroup analyses were performed to evaluate the influences of study characteristics. Results: Eleven retrospective cohort studies were included. Results showed that increased CD44 expression in tumor predicted poor OS in glioma patients (hazard ratio [HR]: 1.42, 95% confidence interval [CI]: 1.02-1.97, P=0.04). Subgroup analyses showed that higher tumor CD44 expression significantly predicted poor OS in patients with World Health Organization (WHO) stages II-III glioma (HR: 2.99, 95% CI: 1.53-5.89, P=0.002), but not in patients with glioblastoma (HR: 1.26, 95% CI: 0.76-2.08, P=0.47; P for subgroup difference = 0.03). Results were not statistically different between subgroups according to patient ethnicity, sample size, CD44 detection method, CD44 cutoff, HR estimation, univariate or multivariate analysis, or median follow-up durations (P-values for subgroup difference all >0.10). Conclusion: Higher tumor expression of CD44 may predict poor survival in patients with glioma, particularly in those with WHO stage II-III glioma.