Detection of micro-metastasis of renal cell carcinoma by CA9 marker using Real-time PCR

The global prognosis of renal cell carcinoma (RCC) remains poor; about 40% of patients will develop metastasis after nephrectomy. There is a strong need to identify the early metastasis. The present study aimed to test if analysis of the CA9 gene in peripheral blood can provide useful information to predict micro metastasis. In this experimental study, patients (n=30) with RCC were evaluated for peripheral blood CA9 expression non-randomly. Data of tumor grade were received from the pathologist. Total RNA extraction and cDNA synthesis were performed. CA9 expression levels of patients were compared with the normal group (n=16) by real - time PCR. The Mann-Whitney U test and Kruskal-wallis test were used to compare CA9 expression levels with tumor grades. SPSS13 was used for data analysis. Six of patients show high CA9 expression (3 in grade I, 2 in grade II, and 1 in grade III) but no significant difference was found between CA9 expression level and tumor grade. After one year follow up, 4 patients were found to have a metastasis but no significant difference was found between CA9 expression level and metastatic patients. On the basis of the results of this study, CA9 is a tumor-specific marker for RCC with a high degree of expression in the conventional RCC. At the same time, the detection of CA9 gene expression in the peripheral blood of patients with RCC may predict increasing risk of micro metastasis.