Background: Using a reverse transcriptase-polymerase chain reaction (RT-PCR) assay, the authors previously determined the expression of MN/CA9 mRNA in renal cell carcinoma (RCC) and its absence in benign renal tissue. In the current study, the utility of an enhanced RT-PCR assay in the detection of renal carcinoma cells in the peripheral blood was assessed.
Methods: An enhanced MN/CA9 RT-PCR assay was applied to peripheral blood samples from a total of 96 patients. Forty-two patients had renal tumors, including 5 with benign renal lesions, 28 with localized RCC, and 9 with metastatic RCC. Fifty-four control patients without renal tumors were similarly tested. Pathologic staging for patients with localized cancer was T1N0M0 for 5, T2N0M0 for 9, and T3N0M0 for 14 patients.
Results: Cells expressing MN/CA9 were detected in 1 of 54 controls (1.8%) and in 18 of 37 cancer patients (49%). Thirteen of twenty eight patients (46%) with localized RCC and 5 of 9 (56%) with metastatic disease tested positive with the assay. No patient with a benign renal tumor exhibited MN/CA9 expression. All blood test results for patients with clear cell RCC were noted to be positive. No correlation was noted between MN/CA9 results and age, gender, or tumor grade. The differences in MN/CA9 results according to T classification were not statistically significant.
Conclusions: The enhanced RT-PCR assay for MN/CA9 is a highly specific technique for detecting circulating renal carcinoma cells in the peripheral blood, and it may prove useful in the diagnosis and monitoring of RCC.