Overexpression of the cancer stem cell marker CD117 predicts poor prognosis in epithelial ovarian cancer patients: evidence from meta-analysis

PURPOSE Cancer stem cells have recently been identified as a key driving factor for tumor metastasis and chemoresistance. CD117 is a well-established cancer stem cell marker, but its clinical significance in epithelial ovarian cancer (EOC) remains controversial. Therefore, we aimed to identify correlations between CD117 expression and clinical features and outcomes in EOC patients in this meta-analysis. MATERIALS AND METHODS A literature search was performed in the PubMed, Cochrane Library, Web of Science, EMBASE, and OVID databases to identify eligible studies. Correlations between CD117 expression and clinicopathological parameters and overall survival or disease-free survival were analyzed. A subgroup analysis was then performed, which was classified by patient ethnicity and age at diagnosis, study sample size, and tumor histological type. RESULTS A total of seven studies enrolling 1,247 EOC patients were included in this meta-analysis. Our results demonstrated that CD117 expression was significantly correlated with age (pooled odds ratio [OR] =1.67, 95% confidence interval [CI] =1.05-2.66), International Federation of Gynecology and Obstetrics stage (pooled OR =1.99, 95% CI =1.31-3.02), tumor differentiation grade (pooled OR =2.46, 95% CI =1.48-4.10), and histological type (pooled OR =1.85, 95% CI =1.05-3.26). EOC patients with high CD117 expression had significantly worse OS (hazard ratio [HR] =1.39, 95% CI =1.03-1.90) than patients with low CD117 expression. However, no significant correlation was found between CD117 expression and disease-free survival (HR =1.31, 95% CI =0.79-2.17). In subgroup analysis, CD117 was identified as a significant prognostic factor for overall survival in European patients (HR =1.59, 95% CI =1.13-2.23), younger patients (<60 years) (HR =1.59, 95% CI =1.10-2.30), studies with sample sizes >200 (HR =1.84, 95% CI =1.32-2.56), and the mixed histological types (HR =1.47; 95% CI =1.08-2.00). CONCLUSION Our meta-analysis suggests that CD117 is associated with EOC progression and can serve as a promising prognostic predictor for EOC patients. However, larger scale multicenter clinical trials are still needed to further validate our results.