Prognostic value of CD44 expression in renal cell carcinoma: a systematic review and meta-analysis

CD44 is a marker of cancer stem-like cells in renal cell carcinoma (RCC). However, the prognostic value of CD44 in RCC remains controversial. This study evaluated the correlation of CD44 expression with the clinicopathological features of RCC through a meta-analysis. We systematically searched PubMed, ISI Web of Science and Embase for relevant studies until February 2015. We collected and analysed data on clinical stage, Fuhrman grade, microvascular invasion, recurrence, five-year overall survival (OS), disease-specific survival (DSS) and disease-free survival (DFS). Twenty studies involving 1672 patients satisfied the inclusion criteria. Results showed that high CD44 expression in RCC was a poor prognostic marker for five-year OS (RR = 0.69, 95% CI 0.60-0.78) in a fixed-effects model and for five-year DSS (RR = 0.46, 95% CI 0.27-0.80) and five-year DFS (RR = 0.63, 95% CI 0.43-0.93) in a random-effects model. CD44 expression also correlated with Furhman grade (RR = 0.61, 95% CI 0.48-0.77), tumour recurrence (RR = 7.42, 95% CI 3.74-14.70) and MVI (Microvascular invasion) (RR = 3.63, 95% CI 1.97-6.71). This meta-analysis suggests that CD44 is a prognostic marker in RCC. High CD44 expression correlates with high Fuhrman grade, recurrence, MVI and poor prognosis.