Expérience de l'Université de Columbia dans la détection des cellules circulantes par RT-PCR PSA dans le cancer de prostate comme facteur prédictif du stade et de la récurrence biologique

Objectives : The Columbia University experience of RT-PCR PSA as a predictive factor of stage and biochemical recurrence is reviewed by trying to explain its differences. Patients and Methods : 319 patients were included between January 1993 and March 1998. Radical prostatectomy was performed in all patients by the same surgeon. The RT-PCR protocol has been previously described (Katz et al., Urology, 1994). Biochemical recurrence was defined by a PSA greater than or equal to 0.2 ng/ml. Results : Histological examination diagnosed 218 pT2 and 101 pT3 tumours. Thirty-four of the 218 pT2 patients (16%) had a positive RT-PCR versus 51 of the 101 pT3 patients (51%, p<0.001). Analysis of Kaplan-Meier curves showed an 84% recurrence-free survival when RT-PER was negative versus 47% when RT-PCR was positive (Log-rank test, p=0.0002). Multivariate analysis showed that independent predictive factors of biochemical recurrence were stage (p=0.004), Gleason score estimated on the operative specimen (p=0.010) and serum PSA (p=0.047); RT-PCR (p=0.075), strongly correlated with stage, was not an independent predictive factor. By exclusively comparing preoperative parameters, PSA (p=0.004) and RT-PCR (p=0.006) were found to be independent predictive factors compared to digital rectal examination (p=0.371) and Gleason score on biopsies (p=0.076). Conclusion : In this institution, RT-PCR PSA is a predictive parameter of stage and biochemical recurrence. No consensus has yet been reached in the literature concerning the reference protocol, as each team has developed its own RT-PCR technique applied to its own patient population. Comparison of results is therefore difficult.