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

Abstract

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.