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Publications (2)12.35 Total impact

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    ABSTRACT: Urologists must contend with fluctuating prostate specific antigen (PSA) results from different assay platforms when deciding whether prostate biopsy is indicated. The contribution of cross-platform variation to these fluctuations is not well understood. To address this question we performed a cross-sectional study comparing 2 popular PSA assays during prostate cancer screening. The Baylor College of Medicine Prostate Cancer Screening Program is a community outreach program providing free screening to Houston residents. From September 18th to 23, 2000, 2,304 patients underwent digital rectal examination and parallel serum PSA assay by the Hybritech Access (Beckman Coulter, Inc., Chaska, Minnesota) and Centaur (Bayer Diagnostics, Tarrytown, New York) systems. The Wilcoxon signed ranks test was used to compare results. Median PSA was low for the 2 assays (Centaur 0.99 ng/ml and Access 1.09 ng/ml) and Access results were significantly higher (1.23 times) than those obtained with Centaur (p <0.001). Frozen serum from 50 patients with PSA greater than 2.5 were then re-assayed using a third methodology (third Generation Immulite, Diagnostic Products Corp., Los Angeles, California). These data were consistent with Centaur results and significantly lower than Access results (p <0.001). Using a cutoff of PSA greater than 4.0 ng/ml 55 of the 288 patients (19%) with PSA greater than 2.5 ng/ml on the 2 platforms would have been candidates for prostate biopsy based on Access but not on Centaur data. In a large screening population the Access system measured consistently higher PSA than the Centaur system. These findings provide a basis for interpreting PSA results obtained from 2 commonly used clinical assays.
    The Journal of Urology 07/2004; 171(6 Pt 1):2234-8. · 3.70 Impact Factor
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    ABSTRACT: Preoperative peripheral blood reverse transcription-PCR (RT-PCR) for prostate-specific antigen (PSA) [RT-PCR-PSA] is not associated with an increased risk of progression after radical prostatectomy. We tested the hypothesis that early postoperative peripheral blood RT-PCR-PSA would detect prostate cancer cells persisting in the circulation that would be associated with disease progression. The study group consisted of 145 consecutive patients who underwent radical prostatectomy for clinically localized disease (median follow-up, 54.5 months) for whom pre- and postoperative peripheral blood samples were available. RT-PCR-PSA was performed on preoperative and postoperative peripheral blood specimens. Pre- and postoperative RT-PCR-PSA were positive in 27% and 12%, respectively, of patients. Most (64%) preoperative RT-PCR-PSA-positive patients converted to a negative RT-PCR-PSA status after prostate removal (P < 0.001). Whereas preoperative RT-PCR-PSA was not associated with prostate cancer characteristics or outcome, a positive postoperative RT-PCR-PSA assay was associated with extracapsular extension (P = 0.044) and seminal vesicle involvement (P = 0.024). Furthermore, postoperative RT-PCR-PSA was an independent predictor of disease progression (P = 0.027). In patients who experienced disease progression, postoperative RT-PCR-PSA was associated with a more aggressive pattern of failure (P = 0.005). Whereas a significant number of patients with clinically localized prostate cancer have prostate cells detectable preoperatively by RT-PCR-PSA circulating in their blood, most of these cells are clinically insignificant because the majority of these patients convert to RT-PCR-PSA-negative status and maintain disease-free status after prostate removal. In contrast, postoperative RT-PCR-PSA detection of prostate cells in the peripheral blood is associated with established markers of aggressive prostate cancer and is an early independent predictor of disease progression, presumably because of an association with established micrometastatic disease.
    Cancer Research 09/2003; 63(18):5874-8. · 8.65 Impact Factor