EPITHELIAL TUMOR-CELL DETECTION AND THE UNSOLVED PROBLEMS OF NESTED RT-PCR - A NEW SENSITIVE ONE-STEP METHOD WITHOUT FALSE-POSITIVE RESULTS

Sensitive detection of circulating epithelial cancer cells might have important therapeutic and prognostic implications in patients with bre ast cancer (BC) receiving high-dose chemotherapy and PBSC support. We have compared the specificity and sensitivity of the recently develope d 'one tube' reverse transcriptase PCR (RT-PCR) assay with the more wi dely used nested RT-PCR method for detection of cytokeratin 19 (CK19)- positive cells. The analysis of 30 control samples provides evidence t hat one tube RT-PCR is highly specific in contrast to the nested metho d which showed 23% false positive results. The sensitivity of both tec hniques to detect tumour contamination was 10(-6). PBSC harvests from 45 BC patients were tested with both RT-PCR methods and the results we re compared with immunocytochemistry (ICC), The five samples found pos itive by ICC were also positive by one tube RT-PCR; in addition, 11 mo re samples were positive by one tube RT-PCR analysis. The greater numb er of PBSC found positive by one tube RT-PCR might be due to the large r number of cells analysed. We conclude that one tube RT-PCR is sensit ive and reveals no false positive results. This method is less time co nsuming than the nested one, technically simpler and should be conside red for tumour cell detection.