Expression of CD24 in clear cell renal cell carcinoma and its prognostic significance

OBJECTIVES To evaluate the expression patterns of CD24 in clear cell renal cell carcinoma (CCRCC) and to investigate its prognostic significance. CD24 is a cell adhesion molecule that has been thought to play an important role in tumor progression and metastasis of various cancers. CD24 expression has previously been reported in RCC, although little is known about its prognostic significance. METHODS We immunohistochemically analyzed CD24 expression using tissue microarray in 328 cases of CCRCC. The percentage of positively stained tumor cells was evaluated and classified into four categories: 0, 0%; 1+, 1% to 10%; 2+, 11% to 50%; and 3+, more than 50%. For statistical analysis, the cases were subdivided into a CD24-low-expression group (0 and 1+) and CD24-high-expression group (2+ and 3+). RESULTS High CD24 expression was significantly associated with a high nuclear grade (P = 0.005) and large tumor size (P = 0.04). The survival analysis revealed no significant association between CD24 expression and disease-specific survival (P = 0.141). However, the CD24-high-expression group had a significantly shortened progress ion-free survival (P = 0.005). Multivariate analysis also revealed that high CD24 expression was an independent covariate for poor progress ion-free survival (P = 0.043). CONCLUSIONS We investigated CD24 expression in CCRCC and found that high CD24 expression was associated with high nuclear grade, large tumor size, and shortened progression-free survival. Although the biologic function of CD24 in CCRCC remains unknown, the expression of CD24 can provide new prognostic information about disease progression.