Alpha-Methylacyl-CoA Racemase Expression in Invasive and Non-Invasive Bladder Urothelial Carcinomas

Objective: alpha-methylacyl-CoA racemase (AMACR) is a useful diagnostic marker for prostatic adenocarcinoma with a high sensitivity and specificity. Although originally viewed as a marker preferentially expressed in prostatic carcinoma, further studies showed its expression in other tumors. The aim of this study is to explore the pathologic significance of AMACR expression in non-invasive and invasive urothelial carcinomas (UCs) of the bladder. Material and Methods: A total of 160 UCs of the bladder and 77 adjacent tissues with carcinoma in situ were investigated for AMACR expression immunohistochemically. Positive AMACR expression was defined as cytoplasmic staining with granular pattern. Staining intensity was graded as 0 (negative), 1+ (weak), 2+ (moderate), or 3+ (strong). Positivity was further classified as focal or diffuse. Results: Non-neoplastic urothelium revealed no expression of AMACR. There was a statistically significant positive correlation between AMACR expression and grade (p = 0.021). AMACR expression was significantly higher in high-grade UCs than low-grade ones. AMACR expression was also correlated with the stage which was significantly higher in invasive tumors (p < 0.001). Although nonsignificant, diffuse staining was prominent in high grade tumors. Conclusion: In the present study, AMACR was found to be expressed in a significant number of urothelial carcinomas of the bladder. AMACR expression was shown to be correlated with advanced tumor grade and stage. Our data suggest that AMACR expression may be used as an additional prognostic indicator in urothelial carcinomas. Evaluation of AMACR expression may also be useful in determining the aggressive capacity of these tumors in transurethral resection specimens.