Optimization of the reverse transcriptase polymerase chain reaction for the detection of circulating prostate cells

The reverse transcriptase polymerase chain reaction (RT-PCR) is a sensitive technique that can detect prostate-specific messenger RNA in circulating b lood. Many authors have studied the potential of RT-PCR as a staging techni que in prostate cancer (PC). Clinical sensitivity and in some cases specifi city has been disappointing. Few authors have been able to correlate RT-PGR result with patient stage. We have compared the results of using two diffe rent RT-PCR protocols with different sensitivities on blood samples from pr ostate cancer patients. An 80-amplification-cycle nested primer RT-PCR assa y had a detection limit of 10 prostate cells and a 50-cycle RT-PCP could de tect 20 cells in 5 mi blood. The 80-cycle assay detected prostate mRNA in f our of 10 female samples, whereas the 50-cycle assay detected it in none. T here was little difference in the assays' ability to detect prostate mRNA i n advanced PC patients. The 50-cycle assay could differentiate between horm one-escaped stable hormone-treated and untreated localized PC patients, whe reas the 80-cycle assay could not, Each blood sample must be assayed severa l times with RT-PCR to avoid false-negative results and, ii this is done, a ssay specificity can be increased with little effect on clinical sensitivit y. (C) 2000 Cancer Research Campaign.