Expression of CD133 Correlates with Tumor Stage, Lymph Node Metastasis and Recurrence in Oral Squamous Cell Carcinoma

Objective: CD133 is a pentaspan membrane protein expressed by the so-called cancer stem cells (CSC) in the majority of human cancers. The aim of this study was to analyze CD133 expression levels in specimens of oral cancer and to evaluate its relation with disease evolution. Methods: Expression of the CD133 protein was evaluated by immunostaining in a series of oral squamous cell carcinoma (OSCC) and its relation with traditional prognostic indicators and the clinical outcome of patients was analyzed. Results: CD133 expression was highly variable amongst different samples with a median percentage of positive cells of 5 (range 0 - 80; mean = 11) and CD133 staining was not detectable in tumor cells in 29 (43%) cases. No correlation was observed with age at diagnosis, gender and grading while a significant correlation was observed with tumor stage. Kaplan-Meier curves of disease-free survival displayed a significant separation between the negative and positive groups of patients (p = 0.001 by log-rank test) but CD133 staining did not confirm to be an independent predictor of clinical outcome in a multivariate analyses. Conclusion: Expression of CD133 was detectable in the majority of OSCC samples and correlated significantly with tumor stage and the clinical outcome of patients in terms of disease-free survival. Further studies are warranted on a larger series of cases to elucidate the role of CD133 in the development and progression of OSCC and its suitability as a prognostic biomarker.