Prostate cancer antigen 3 score accurately predicts tumour volume and might help in selecting prostate cancer patients for active surveillance.

Abstract

The optimal selection of prostate cancer (PCa) patients for active surveillance (AS) is currently being debated. To assess the impact of urinary prostate cancer antigen 3 (PCA3) score as an AS criterion instead of and in addition to the current criteria. We prospectively studied 106 consecutive low-risk PCa patients (prostate-specific antigen [PSA] ≤10 ng/ml, clinical stage T1c-T2a, and biopsy Gleason score 6) who underwent a PCA3 urine test before radical prostatectomy (RP). Performance of AS criteria (biopsy criteria, PCA3 score, PSA density, and magnetic resonance imaging [MRI] findings) was tested in predicting four prognostic pathologic findings in RP specimens: (1) pT3-4 disease; (2) overall unfavourable disease (OUD) defined by pT3-4 disease and/or pathologic primary Gleason pattern 4; (3) tumour volume <0.5 cm(3); and (4) insignificant PCa. The PCA3 score was strongly correlated with the tumour volume in a linear regression analysis (p<0.001, r=0.409). The risk of having a cancer ≥0.5 cm(3) and a significant PCa was increased three-fold in men with a PCA3 score of ≥25 compared with men with a PCA3 score of <25 with most AS biopsy criteria used. There was a trend towards higher PCA3 scores in patients with unfavourable and non-organ-confined disease and Gleason >6 cancers. In a multivariate analysis taking into account each AS criterion, a high PCA3 score (≥25) was an important predictive factor for tumour volume ≥0.5 cm(3) (odds ratio [OR]: 5.4; p=0.010) and significant PCa (OR: 12.7; p=0.003). Biopsy criteria and MRI findings were significantly associated with OUD (OR: 3.9 and 5.0, respectively; p=0.030 and p=0.025, respectively). PCA3 score may be a useful marker to improve the selection for AS in addition to the current AS criteria. With a predictive cut-off of 25, PCA3 score is strongly indicative for tumour volume and insignificant PCa.