Ron S. Israeli

Can prostate-specific antigen reverse transcriptase-polymerase chain reaction be used as a prospective test to diagnose prostate cancer ?

The present study addressed the question as to whether prostate-specific antigen reverse transcriptase-polymerase chain reaction (PSA RT-PCR) could be used to identify prospectively men who have prostate cancer and to help determine which patients with an initially negative biopsy would benefit from rebiopsy. PSA RT-PCR was performed prospectively on 90 patients who were to have a prostate biopsy because of an elevated PSA level, an abnormal digital rectal examination, or both. PSA RT-PCR was performed, and the sensitivity of the test was enhanced by hybridization of the PCR with a32p-labeled PSA cl)NA probe (exons 3–5). Of the 90 men, 36 (40%) had prostate cancer on biopsy. Of these 36 men, 5 (13.9%) had a positive PSA RT-PCR finding, whereas 31 (84.1%) tested negative. Of 54 men with negative biopsies, 8 (14.8%) had a positive PSA RT-PCR result. The sensitivity of PSA RT-PCR for the detection of biopsy-proven prostate cancer was 13.9% and the specificity was 85.2%. Only 3 of 12 (25%) patients with advanced disease had a positive test result. The sensitivity of PSA RT-PCR for the detection of biopsy-proven prostate adenocarcinoma in men suspected of having prostate cancer is poor. Indeed, men without biopsy-proven prostate cancer are just as likely to have a positive result in the PSA RT-PCR as are men with cancer. Whether these men with negative prostate biopsies and positive PSA RT-PCR findings may eventually develop prostate cancer remains to be determined. At this time, PSA RT-PCR for the prospective detection of prostate cancer should be considered investigational.

Effect of prostate biopsy on the results of the PSA RT-PCR test

OBJECTIVES To evaluate the effect of prostate biopsy on the prostate-specific antigen (PSA) reverse transcriptase-polymerase chain reaction (RT-PCR) test. METHODS Ninety men who were scheduled to undergo prostate biopsy because of an elevated PSA or abnormal digital rectal examination, or both, were recruited to have PSA RT-PCR performed on peripheral blood samples drawn before and at 30 minutes, 1 week, and 1 month after undergoing prostate biopsy. PSA RT-PCR was performed and all PCR products were blotted and hybridized with phosphorus-32 (32-P)-PSA cDNA probe (exon 3 to 5). RESULTS Of 90 patients, 77 had a negative prebiopsy PSA RT-PCR result. Of these 77, 2 (2.6%) had a positive PSA RT-PCR result at some point after the biopsy procedure. Both of these patients had no evidence of malignancy on biopsy. The PSA RT-PCR test was positive at 30 minutes for 1 patient, but was negative at 1 week; the other was positive at 1 week but the patient did not return for the 1-month sample. CONCLUSIONS Our study indicates that 2.6% of patients with an initially negative PSA RT-PCR will have a positive PSA RT-PCR test after biopsy has been performed. Although this is uncommon, it may have profound implications for those patients in whom it occurs. On the basis of our results, it appears that one should wait longer than 1 week after prostate biopsy before obtaining blood for PSA RT-PCR testing to decrease the likelihood of a spurious PSA RT-PCR result.