Quantitative RT-PCR analysis of PSA and prostate-specific membrane antigen mRNA to detect circulating tumor cells improves recurrence-free survival nomogram prediction after radical prostatectomy

BACKGROUND Circulating tumor cell (CTC) analysis is a potential new biomarker in prostate cancer. We hypothesize that quantitative detection of CTCs in patients pre‐ and post‐radical prostatectomy (RP) using quantitative TaqMan® fluorogenic RT‐PCR will improve the accuracy of the Kattan nomogram to predict the probability of recurrence‐free survival (RFS) post‐RP. METHODS Ninty‐two patients who underwent RP between 2004 and 2009 had venous blood samples taken pre‐ (Day − 1) and post‐operatively (Day + 7). We performed quantitative Taqman® RT‐PCR to detect circulating prostate‐specific antigen (PSA) and prostate‐specific membrane antigen (PSMA) mRNA. We calculated both the logarithmic ratio of Day + 7/Day − 1 for PSA (PSAr) and PSMA (PSMAr) expression (logDay+7/Day−1) and the Kattan nomogram predicted probability of disease recurrence for each patient. We then analyzed how the AUC‐ROC analysis for the Kattan nomogram prediction alone (K) compared to the addition of the PSAr and PSMAr in predicting 5‐year RFS. RESULTS The mean age (years), PSA (ng/ml), and follow‐up (mo) was 65.1, 9.13, and 72, respectively. The AUCs for K, PSAr + K, and PSMAr + K were 0.752 (95%CI 0.620–0.860), 0.830 (95%CI 0.740–0.911), and 0.837 (95%CI 0.613–0.923), respectively (P = 0.03). The Kattan 5‐year PSA RFS was 75%. The actual 5‐year PSA RFS survival rate was 77%. CONCLUSIONS Data from modern quantitative RT‐PCR to detect circulating prostate‐derived PSA and PSM mRNA pre‐ and post‐RP improves the accuracy of the Kattan nomogram to predict biochemical recurrence. Prostate 72:1382–1388, 2012. © 2012 Wiley Periodicals, Inc.