CA9 as a biomarker in preoperative biopsy of small solid renal masses for diagnosis of clear cell renal cell carcinoma.

PURPOSE

The purpose of our study was to test the utility of CA9 expression in preoperative biopsy samples to identify the ccRCC.

MATERIALS AND METHODS

A total of 55 patients with a small solid renal mass (≤4 cm) entered into this study. The immunohistochemical staining (51 samples) and RT-PCR (33 samples) were performed to detect CA9 expression.

RESULTS

For immunohistochemistry detection, CA9 was positive in 31/34 of biopsy samples of ccRCCs. CA9 was also positive in five suspected diagnosis of ccRCC. For RT-PCR detection, CA9 was positive in 25/25 biopsy samples of ccRCCs. The diagnostic accuracy of CA9 expression for ccRCC was 100%. RT-PCR was performed in four biopsies where immunohistochemistry could not be performed because of limited tissue materials or necrosis. Two ccRCCs with a negative staining by immunohistochemistry were CA9 positive by RT-PCR.

CONCLUSIONS

CA9 may be potentially useful biomarker in help making a diagnosis of ccRCC in the biopsy of renal mass. RT-PCR might be a preferred method to immunohistochemistry for the detection of CA9 in renal biopsy samples.