The value of a reverse transcriptase polymerase chain reaction assay in preoperative staging and followup of patients with prostate cancer.

PURPOSE

The reverse transcriptase polymerase chain reaction (RT-PCR) assay is an extremely sensitive technique of detecting cells expressing prostate specific antigen (PSA). Controversy exists regarding the ability of peripheral blood PSA RT-PCR testing to reflect pathological staging or treatment outcome. We examine the phenomenology of RT-PCR results in patients with prostate cancer, with particular emphasis on the RT-PCR test before and after radical prostatectomy, and correlations with pathological staging and treatment outcome.

MATERIALS AND METHODS

Peripheral blood was obtained from a wide variety of patients with and without prostate cancer, including before and after radical prostatectomy. After ribonucleic acid isolation, complementary deoxyribonucleic acid was generated and amplified with a hot-start technique. RT-PCR results were compared with pathological stage, Gleason score, tumor volume and disease-free status. Correlations between preoperative and postoperative RT-PCR tests were also made.

RESULTS

The RT-PCR test was positive in 1 of 56 controls (1.8%) without suspicion of prostate cancer. A positive test was obtained in 12 of 65 men (18.5%) with a suspicion of prostate cancer but a negative biopsy. Before radical prostatectomy a positive test was obtained in 13 of 75 men (17.3%) with pT2 disease versus 10 of 46 (21.7%) with pT3 disease. There was no significant difference in serum PSA, Gleason score or tumor volume between the men with positive or negative results. With repetitive testing an increasing percentage of men had at least 1 positive test preoperatively. With a median followup of 8 months 6 of the 7 patients in whom radical prostatectomy failed had had negative RT-PCR before treatment. Of patients with known metastatic disease or failed primary treatment a positive test was obtained in 32 to 75%. Radical prostatectomy and prostate needle biopsy appeared to have a negligible effect on RT-PCR tests immediately following these procedures. Following radical prostatectomy results were variable but many men who are RT-PCR positive preoperatively become RT-PCR negative postoperatively.

CONCLUSIONS

The PSA RT-PCR test in our laboratory cannot be used preoperatively to predict pathological stage of prostate cancer or treatment failure. Most cases that are positive preoperatively become negative postoperatively. While increasing tumor burden increases the likelihood of positive tests, there appears to be significant sampling error associated with the use of this test in the peripheral blood.