Molecular detection of circulating cancer cells in patients with renal cell carcinoma

We have developed a highly sensitive technique to detect circulating renal cell carcinoma (RCC) cells in the blood using the reverse transcriptase-polymerase chain reaction (RT-PCR) with primers specific for the MN/CA9 gene. RT-PCR analysis of RCC specimens resulted in the clear detection of MN/CA9 mRNA signal in 93%. In contrast, no expression of MN/CA9 was observed in normal kidney specimens. Highly sensitive RT-PCR analysis of blood samples from RCC patients revealed the presence of circulating MN-positive cancer cells in the blood. Fifty samples obtained from the patients with RCC and 31 samples from healthy donors were investigated. The sensitivity and specificity of this RT-PCR analysis were 72% and 78%, respectively. These findings suggest that the MN antigen may be a potential diagnostic biomarker for early detection of RCC.