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Association of declining PSA values with a lower risk of progression in the Canary Prostate Cancer Active Surveillance Study (PASS).

88 Background: Active Surveillance of men with low risk prostate cancer entails uncertainty for the patient and physician in determining risk of progression. While PSA determinations are frequently measured in men on active surveillance, no study thus far has found PSA velocity (PSAV) or PSA doubling times that identify patients at risk for clinical progression. However, based on observations in PASS, we hypothesized that men with negative PSAV might be at decreased risk for progression.


METHODS
From 723 PASS participants, we identified 396 who had at least 5 PSA values over 12-24 months after their diagnosis and prior to progression or last follow-up. Of the 396 patients, 56 progressed as defined by increase in Gleason score or increase in tumor involvement of the core biopsies to ≥ 34%, or increase in clinical stage while 340 men had no progression. PSAV is the slope of the log(PSA) values over time. ROC analysis was used with PSAV as the predictor of biopsy/clinical progression.


RESULTS
PSAV was mildly associated with clinical/biopsy progression with an AUC of 0.62 (95% CI: 0.54-0.70). Interestingly, by thresholding PSAV at 0, 150 of 396 men had negative a PSAV. Subjects with with a negative PSAV had a much lower rate of progression while on active surveillance. PSAV<0 had a negative predictive value for progression of 0.93 (95% CI: 0.88-0.97). The progression rate for those with negative PSA velocity was 11/150 ≈ 0.07, or 7% and 18% (45/246) for those with positive PSA velocity. Viewed another way, men with PSAV<0 had a 0.4 fold relative risk of progression compared to men with a positive PSAV or were 60% less likely to have clinical/grade progression than those with positive PSA velocity (95% CI: 0.21-0.75).


CONCLUSIONS
Declining PSAV in men on active surveillance for clinically localized prostate cancer is associated with a lower risk of clinical progression.


CLINICAL TRIAL INFORMATION
NCT00756665.