Glen M. de Vries

Enhanced reverse transcriptase-polymerase chain reaction for prostate specific antigen as an indicator of true pathologic stage in patients with prostate cancer

Background. As up to 50% of all patients with prostate cancer who have undergone radical prostatectomy are found to be understaged subsequent to surgery, a more sensitive early staging modality currently is needed. A molecular assay that detects prostate specific antigen (PSA)‐synthesizing cells in the peripheral circulation of patients with prostate cancer is described.

Preoperative Reverse Transcriptase Polymerase Chain Reaction for Prostate Specific Antigen Predicts Treatment Failure Following Radical Prostatectomy

PURPOSE We previously demonstrated than an enhanced reverse transcriptase-polymerase chain reaction assay for prostate specific antigen (PSA) can predict final pathological stage in radical prostatectomy patients. The potential role of the assay in predicting serum PSA recurrence after radical prostatectomy was explored. MATERIALS AND METHODS We evaluated 100 radical prostatectomy candidates by reverse transcriptase polymerase chain reaction preoperatively, and status was compared to serum PSA, Gleason score and final pathological results. Potential surgical failure was defined as tumor at the surgical margin or extending into the seminal vesicle. Patients were monitored postoperatively by serum PSA every 4 months. Kaplan-Meier analysis was used to evaluate the correlation between reverse transcriptase polymerase chain reaction and disease recurrence, defined as a PSA of 0.2 ng/ml. or greater. RESULTS Enhanced reverse transcriptase polymerase chain reaction for PSA had a stronger correlation with potential surgical failure than preoperative serum PSA or Gleason score (relative risks 15.2, 5.9 and 3.2, respectively). The correlation between these modalities and PSA recurrence was evaluated during a mean followup of 13.6 months (range 5 to 26). Of 36 patients with positive reverse transcriptase polymerase chain reactions 9 had failure by PSA compared to 3 of 64 (4.7%) with negative polymerase chain reactions (p<0.0286). The relative risk for failure by reverse transcriptase polymerase chain reaction was 3.6. Gleason score and serum PSA had higher correlations with postoperative PSA elevations (relative risk 13.2 and 7.6, respectively). A Cox regression analysis model demonstrated that reverse transcriptase polymerase chain reaction for PSA can be used in conjunction with Gleason score and provides statistically significant risk information. CONCLUSIONS Enhanced reverse transcriptase polymerase chain reaction for PSA is a statistically significant predictor of potential failure by pathological analysis and of disease recurrence by PSA. Longer followup data are required to define further the role of the assay in the management of patients with prostate cancer.

REVERSE TRANSCRIPTASE-POLYMERASE CHAIN REACTION ASSAYS FOR PROSTATE CANCER

RT-PCR, if targeted against a prostate-specific marker, can be a highly specific and sensitive assay to detect the presence of occult prostate cancer cells at sites far distant from the primary tumor. The low false-positive rate (0.8%) observed when combining most published studies and the high rate of detection of prostate cells in metastatic patients (88%) found in well-defined clinical studies address the basic requirements of a clinically effective diagnostic modality. Additionally, all reports indicate that RT-PCR positivity for PSA or PSMA increases with increased stage of prostate cancer, suggesting that RT-PCR assays may have value in staging the patient presumed to have clinically localized disease. Indeed, data from two institutions have shown the unique contribution that RT-PCR technology might lend to this most vexing problem. With the suggestive data already published, we remain optimistic that molecular staging will become a reality in the future. After all, the variability in techniques of RT-PCR (as well as differences in targets and samples assayed) used by the various laboratories now investigating this method could themselves be responsible for many of the differences reported. There is no question that standardization among laboratories is essential before clinical utility of molecular staging can be proved. Indeed, this endeavor represents the major aim of the RT-PCR consortium in the United States. Nevertheless, at our own medical center, we are struck by our finding that if a preoperative RT-PCR for PSA is negative, the patient can be assured of a successful operative outcome in 88% of cases. We also are impressed by the data showing that if the serum PSA level is greater than 10 ng/mL and the RT-PCR assay is positive, 90% of patients undergoing radical surgery have adverse pathology reports (and, in fact, have already experience operative failure in nearly half the cases). There is increasing consensus that RT-PCR assays afford prognostic information that is also unique. Three institutions have similar data comparing operative or preoperative RT-PCR strategies (employing all three potential sample sources) with treatment outcome. This may suggest the validity of RT-PCR as a staging modality or, alternatively, suggest that a truly metastatic phenotype is identified in patients with circulating PSA-synthesizing cells, or in patients harboring PSA-synthesizing cells in node or marrow tissues. In either case, RT-PCR appears already to provide information not available before the use of this technology. In fact, in the only series comparing RT-PCR with other, more established predictors (PSA, Gleason score) in a multivariate analysis, RT-PCR status provided the best prognostic information. Prostate manipulation does, in fact, appear to affect the RT-PCR assay. Although digital rectal examination and cystoscopy do not seem sufficiently invasive to release prostate cells into the circulation, a small number of individuals undergoing transrectal ultrasound biopsy will experience this phenomenon. This observation provides a cautionary note relative to timing of sample collection for RT-PCR assays. Furthermore, a significant fraction of patients undergoing prostate manipulation during radical surgery may experience shedding of prostate cells into the operative field and release of some into the peripheral circulation. This has not been universally observed and, even if true, may not share the significance of spontaneous RT-PCR positivity (before prostatic manipulation). In the one instance, a potentially metastatic phenotype is responsible for RT-PCR positivity, whereas in the other instance, PSA or PSMA synthesizing cells may have no metastatic potential at all. Further studies on the biologic half-life of such cells are required before any clinical judgement can be made regarding this phenomenon. In summary, there appears to be consensus that RT-PCR technology can differentiate controls from patients with metas

Detection of circulating prostate carcinoma cells via an enhanced reverse transcriptase-polymerase chain reaction assay in patients with early stage prostate carcinoma†

Circulating prostate cells can be detected in the venous blood of patients with clinically localized prostate carcinoma by applying reverse transcriptase‐polymerase chain reaction (RT‐PCR) techniques using primers specific for the prostate specific antigen (PSA) gene. This study evaluates whether the detection of circulating cells correlates with established prognostic factors, treatment, and pathologic stage.

THE ROLE OF THE REVERSE-TRANSCRIPTASE POLYMERASE CHAIN REACTION ASSAY FOR PROSTATE-SPECIFIC ANTIGEN IN THE SELECTION OF PATIENTS FOR RADICAL PROSTATECTOMY

Prostate cells present in the peripheral circulation can be detected using an enhanced reverse-transcriptase polymerase chain reaction (RT-PCR) for prostate-specific antigen (PSA) assay. In one study, preoperative enhanced RT-PCR for PSA status was a significant predictor of surgical pathology and postoperative biomechanical recurrence. The use of RT-PCR may enhance the urologists ability to stage potential candidates for radical prostatectomy, as the assay is a more sensitive and specific predictor of microscopic extracapsular extension than conventional staging modalities. This highly adaptable assay also may have roles in screening for recurrence and in staging other solid tumors.

Enhanced reverse transcriptase polymerase chain reaction for prostate-specific antigen combined with needle biopsy results: A superior predictor of pT3 disease

Background: Preoperative staging for prostate cancer underestimates the final pathology stage in approximately 40-50% of the cases. Previous work from our institution demonstrated that an enhanced reverse transcriptase polymerase chain reaction (RT-PCR) assay for prostate-specific antigen (PSA) enabled more accurate staging of presumably localized prostate cancer. The goal of the current study is to determine if needle biopsy results when combined with the RT-PCR for PSA assay are a better predictor of final pathology stage. Methods and Results: One hundred sixty-two men with needle biopsy-diagnosed prostate cancer had blood drawn for the RT-PCR for PSA assay before undergoing radical prostatectomy. Polymerase chain reaction primers specific for the PSA gene were run, along with appropriate controls. Tumor was characterized using the TMN staging system: organ confined (pT2a-c), capsular penetration (pT2a-b), seminal vesicle involvement (pT3c). Surgical margins and lymph nodes were also evaluated. Of the 162 patients, the majority had localized disease by digital rectal examination: T2 = 97%, and T3 = 3%. On needle biopsy, 48 cases (30%) had a Gleason score >/=7 and 35 cases (22%) had perineural involvement (PNI). The RT-PCR for PSA assay was positive in 50 patients (31%). Final pathology revealed 39% of patients had pT3 disease; none of the 162 patients had lymph node involvement. Statistical analysis revealed that a Gleason score >/=7 had 81% specificity and 46% sensitivity in predicting pT3 disease (odds ratio 3.6). The presence of PNI on needle biopsy was 89% specific and 38% sensitive in predicting pT3 disease (odds ratio, 4.9). The RT-PCR for PSA assay was 89% specific and 62% sensitive in predicting pT3 disease (odds ratio, 13.0). All 14 cases with both RT-PCR for PSA and PNI positivity had pT3 disease. Logistic regression analysis demonstrated the independent predictive strength of PNI on needle biopsy, Gleason score >/=7, and RT-PCR for PSA positivity for identifying pT3 disease; their combined odds ratio was more than 180. Conclusions: Using the RT-PCR for PSA assay in conjunction with needle biopsy results increases the predictive strength for pT3 disease in patients with presumed organ-confined prostate carcinoma.