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Sensitivity of [-2]proPSA (p2PSA) measurements for prediction of biochemical recurrence (BCR) in men after radical prostatectomy: a 3-years prospective cohort study

Login to Access Video or Poster Abstract: MP28-04
Sources of Funding: Beckman Coulter

Introduction

Although radical prostatectomy (RP) offers a high overall cancer control rate, even in appropriately selected men, up to a third will experience failure (biochemical recurrence: BCR). PSA has been particularly considered valuable for the detection of BCR defined as a PSA concentration of at least 0.2 ng/ml. Recently, the will to detect the earliest sign of recurrence have led to the development of ultrasensitive PSAs (uPSA), but the usefulness of ultrasensitive assays has not been established. As [-2]proPSA (p2PSA), introduced in clinical practice with its derivate PHI (prostate health index), is normally expressed in pg/mL, it could be more sensible than PSA and uPSA for detecting early BCR after RP. In this study we test the hypothesis that p2PSA (index test) may detect BCR earlier than reference standard test (tPSA) in patients who underwent RP for localised prostate cancer (PCa)._x000D_

Methods

The current study is an observational, prospective, cohort study in a contemporary series of consecutive patients subjected to RP for clinically localized PCa from January 2013 to June 2013. Biochemical follow-up consisted of a blood sample for reference standard test (PSA) and index test (p2PSA), after 3-6-12-18-24-30-36 months. The blood samples were processed with the UniCel DxI800 Immunoassay System analyzer (Beckman Coulter Inc., Brea, CA, USA) and managed according to the criteria described by Semjonow et al using the Hybritech calibration. BCR was defined as a confirmatory PSA concentration of 0.2 ng/ml or greater. A value of 0.8 pg/ml was considered the Limit of Detection (LoD) for p2PSA after RP as previously described. The primary outcome was to investigate the sensitivity of both tests for BCR, while the secondary end point was to determine whether or not results are consisting with different pathological outcome. Descriptive statistical analysis were complemented by Cox proportional hazards models, McNemar test and Kaplan-Meier curves for BCR-free survival by PSA and p2PSA cut-offs

Results

Over 145 eligible patients, 134 men were enrolled and were followed-up for 3 years. The frequencies of positive subjects, identified with p2PSA cut-off, were significantly higher in all the follow-ups than frequencies of positive subjects identified with PSA cut-off (p<0.0001). Overall we observed 18 BCR according to PSA. Five patients showed a contemporary increase of PSA and p2PSA, while 9 men presented a p2PSA increase earlier than PSA (mean time 4.9±3.1 months vs. 18.8±7.3 respectively). In 4 patients the increase of PSA was not associated with a p2PSA > 0.8 pg/ml. The analysis of Kaplan-Meier curves for BCR-free survival showed a significant lower time for p2PSA (16.7 mo; 95%CI: 14.1-19.2) respect to PSA (35.6 mo; 95%CI: 34.0-33.2). When subjects were stratified according to stage/grade and margins (positive vs. negative), patients with pT2c-GS3+4/4+3-R1 and pT3a-R0/1 could be considered the target categories, which would benefit more from the p2PSA LoD.

Conclusions

The current findings confirm that p2PSA could be more sensitive than tPSA in detecting early BCR at a mid term-follow-up (3 years). This is a confirmation of a previous paper of ours with a shorter follow-up (18 months). Further studies with a longer follow-up and larger population remain mandatory before considering p2PSA for clinical practice purposes

Funding

Beckman Coulter

Authors
Massimo Lazzeri
Giovanni Lughezzani
NicolòMaria Buffi
Giuliana Lista
Paolo Casale
Rodolfo Hurle
Alberto Saita
Silvia Zandegiacomo
Luisa Pasini
Alessio Benetti
Roberto Peschechera
Pasquale Cardone
Ferruccio Ceriotti
Marina Pontillo
Vittorio Bini
Giorgio Guazzoni
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