Assessment of optimal target genes for detecting micrometastases in pelvic lymph nodes in patients with prostate cancer undergoing radical prostatectomy by real-time reverse transcriptase-polymerase chain reaction.

OBJECTIVES

To compare the accuracy to diagnose micrometastases to pelvic lymph nodes (LNs) in patients undergoing radical prostatectomy (RP) by real-time reverse transcriptase-polymerase chain reaction (RT-PCR) targeting several genes specifically expressed in the prostate.

MATERIALS AND METHODS

Expression of prostate-specific antigen (PSA), prostate-specific membrane antigen (PSMA), human kallikrein 2 (hK2), prostate stem cell antigen (PSCA), and differential display code 3 (DD3) in 2215 LNs isolated from 120 patients with localized prostate cancer were assessed by fully quantitative real-time RT-PCR.

RESULTS

In addition to pathologically diagnosed LN metastases in 11 patients, real-time RT-PCR targeting PSA, PSMA, hK2, PSCA, and DD3 further identified micrometastases in 23, 29, 31, 15, and 11, respectively. In this series, biochemical recurrence (BR) occurred in 32 patients, of whom 25, 22, 28, 10, and 9 were diagnosed as having micrometastases by real-time RT-PCR targeting PSA, PSMA, hK2, PSCA, and DD3, respectively. Univariate analysis identified pathologic stage, pathologic LN metastases, Gleason score, surgical margin status, and micrometastases detected by real-time RT-PCR targeting PSA, PSMA, hK2, and their combinations as significant predictors for BR-free survival (BRFS), of which only surgical margin status and micrometastases detected by real-time RT-PCR targeting PSA and hK2 appeared to be independently associated with BRFS on multivariate analysis.

CONCLUSIONS

Of PSA, PSMA, hK2, PSCA, DD3, and their combinations, combined analysis of PSA and/or hK2 expression in pelvic LNs by real-time RT-PCR could provide findings most precisely predicting BRFS following RP.