Prognostic role of CD133 expression in colorectal cancer: a meta-analysis

BACKGROUND: CD133 has been identified as a putative cancer stem cell marker in colorectal cancer (CRC). However, the clinical and prognostic significance of CD133 in CRC remains controversial. METHODS: Publications were identified which assessed the clinical or prognostic significance of CD133 in CRC up to October 2012. A meta-analysis was performed to clarify the association between CD133 expression and clinical outcomes. RESULTS: A total of 12 studies met the inclusion criteria, and comprised 3652 cases. Analysis of these data showed that CD133 was not significantly associated with the depth of CRC invasion (odds ratio [OR] = 1.44, 95% confidence interval [CI]: 0.77–2.68, Z = 1.15, P = 0.252) or tumor differentiation (OR = 0.63, 95% CI: 0.28–1.46, Z = −1.06, P = 0.286). Also, there was no statistically significant association of CD133 with lymph node metastasis (OR = 1.16, 95% CI: 0.87–1.54, Z = 1.05, P = 0.315) or lymphatic invasion (OR = 1.08, 95% CI: 0.81–1.43, Z = 0.53, P = 0.594). However, in identified studies, overexpression of CD133 was highly correlated with reduced overall survival (relative risk [RR] = 2.14, 95% CI: 1.45–3.17, Z = 3.81, P = 0.0001). CONCLUSIONS: CD133 may play an important role in the progression of CRC, and overexpression of CD133 is closely related with poorer patient survival. If these findings are confirmed by well-designed prospective studies, CD133 may be a useful maker for clinical applications.