CD24 overexpression in cancer development and progression: A meta-analysis

CD24 has emerged as a new oncogene and metastasis promoter. However, there is a controversy as to whether CD24 expression is a prognostic factor for poor outcomes in many human cancers. To shed light on this controversy, we performed a meta-analysis of the relationship between CD24 expression and prognostic parameters in different carcinomas. Studies published in the period 1990-2009 were reviewed for the meta-analysis and selected according to defined criteria. The effect sizes of prognostic parameters and overall survival were calculated by an odds ratio (OR) or an adjusted hazard ratio (HR). Twenty-eight studies reported CD24 expression for 2,925 cases. The frequency of CD24 expression by immunohistochemistry was 68% in all the carcinomas of the breast, female genital tract, gastrointestinal tract, biliary tract and pancreas, urinary system, prostate and skin. Overall, CD24 was more frequently overexpressed in their carcinomas than their benign lesions (OR=4.21; 95% CI, 1.826-9.731; P=0.001) and was significantly associated with lymph node metastasis (OR=2.41; CI, 1.013-5.720; P=0.047), advanced clinical stages (OR=1.59; 95% CI, 1.244-2.032; P<0.001) and shortened overall survival (HR=2.13; 95% CI, 1.656-2.730; P<0.001). CD24 expression was highly associated with lymph node metastases in breast cancer (OR=3.55; 95% CI, 1.664-7.554; P=0.001), advanced clinical stages (OR=2.22; 95% CI, 1.442-3.418; P<0.001) and lymphovascular invasions (OR=2.78; 95% CI, 1.522-5.068; P=0.001) in urothelial carcinomas and with higher grades in endometrial adenocarcinomas (OR=3.88; 95% CI, 1.548-9.715; P=0.004). CD24 was more frequently and strongly expressed in breast (OR=35.80; 95% CI, 8.907-143.921; P<0.001) and ovarian carcinomas (OR=35.92; CI, 7.156-180.311; P<0.001), than in their benign counterparts. In conclusion, the meta-analysis strongly supports the idea that CD24 is an important marker of malignancy and poor prognosis in various cancers. In particular, CD24 may promote cancer development and progression in the breast, ovary and urinary bladder.