To assess the utility of urinary prostate cancer antigen 3 (PCA3) as both a one-time and longitudinal measure in men on active surveillance (AS).METHODS:
The Johns Hopkins AS program monitors men with favorable-risk prostate cancer with serial PSA, digital rectal examination (DRE), prostate magnetic resonance imaging and prostate biopsy. Since 2007, post-DRE urinary specimens have also been routinely obtained. Men with multiple PCA3 measures obtained over ≥ 3 years of monitoring were included. Utility of first PCA3 score (fPCA3), subsequent PCA3 (sPCA3) and change in PCA3 were assessed for prediction of Gleason grade reclassification (GR, Gleason score >6) during follow-up.RESULTS:
In total, 260 men met study criteria. Median time from enrollment to fPCA3 was 2 years (interquartile range (IQR) 1-3) and from fPCA3 to sPCA3 was 5 years (IQR 4-6). During median follow-up of 6 years (IQR 5-8), 28 men (11%) underwent GR. Men with GR had higher median fPCA3 (48.0 vs 24.5, P = 0.007) and sPCA3 (63.5 vs 36.0, P = 0.002) than those without GR, while longitudinal change in PCA3 did not differ by GR status (log-normalized rate 0.07 vs 0.06, P = 0.53). In a multivariable model including age, risk classification and PSA density, fPCA3 remained significantly associated with GR (log(fPCA3) odds ratio = 1.77, P = 0.04).CONCLUSIONS:
PCA3 scores obtained during AS were higher in men who underwent GR, but the rate of change in PCA3 over time did not differ by GR status. PCA3 was a significant predictor of GR in a multivariable model including conventional risk factors, suggesting that PCA3 provides incremental prognostic information in the AS setting.