Prognostic value of CD44 expression in non-small cell lung cancer: a systematic review

Background: CD44 is a potentially interesting prognostic marker and therapeutic target in non-small cell lung cancer (NSCLC). Although the expression of CD44 has been reported to correlate with poor prognosis of NSCLC in most literatures, some controversies still exist. Since the limited patient numbers within independent studies, here we performed a meta-analysis to clarify the correlations between CD44 expression and prognosis and clinicopathological features in NSCLC.

Methods: Relevant literatures were identified using PubMed, EMBASE and CNKI (China National Knowledge Infrastructure) databases (up to February 2014). Data from eligible studies were extracted and included into meta-analysis using a random effects model. Studies were pooled. Summary hazard ratios (HR) and clinical parameters were calculated.

Results: We performed a final analysis of 1772 patients from 23 evaluable studies for Prognostic Value and 2167 patients from 28 evaluable studies for clinicopathological features. Our study shows that the pooled hazard ratio (HR) of overexpression CD44-V6 for overall survival in NSCLC was 1.63 [95% confidence interval (CI): 1.20-2.21] by univariate analysis and 1.29 (95% CI: 0.71-2.37) by multivariate analysis.The pooled HR of overexprssion panCD44 for overall survival in NSCLC was 1.53 (95% CI: 0.58-4.04) by univariate analysis and 3.00 (95% CI: 1.53-5.87) by multivariate analysis. Overexpression of CD44-V6 is associated with tumor differentiation (poor differentiation, OR = 1.66, 95% CI: 1.12-2.45), tumor histological type [squamous cell carcinomas (SCC), OR = 2.6, 95% CI: 1.63-5.02], clinical TMN stage (TMN stage III, OR = 2.22, 95% CI: 1.44-3.43) and lymph node metastasis (N1-3, 3.52, 95% CI: 2.08-5.93) in patients with NSCLC. However, there was no significant association between CD44-V6 and tumor size [T category, OR = 1.42, 95% CI: 0.73-2.78].

Conclusion: Our meta-analysis showed that CD44-V6 is an efficient prognostic factor for NSCLC. Overexpression of CD44-V6 was significantly associated with tumor differentiation, tumor histological type, clinical TMN stage and lymph node metastasis. However, there was no significant association between CD44-V6 and tumor size. Large prospective studies are now needed to confirm the clinical utility of CD44 as an independent prognostic marker.