Conditional Probability of Reclassification in an Active Surveillance Program for XXXX .

@entity1 @entity258 @entity263
PURPOSE: We evaluated the risk of @entity263 reclassification by time on active surveillance. MATERIALS AND METHODS: From 1995 to 2014 we evaluated 557 and 251 @entity1 at very low and at low risk, respectively, who were on active surveillance and compliant with prostate biopsies. Our primary study outcome was reclassification to higher risk disease by grade or extent. Freedom from reclassification was estimated using the Kaplan-Meier approach with adjustment for covariates using the Cox proportional hazards model. RESULTS: Within the first 2 years of surveillance @entity1 survival free of reclassification by grade (p = 0.20) and by any biopsy criteria (p = 0.25) was similar in @entity1 with very low and @entity258 . After 2 years @entity1 with @entity258 were 2.4 times more likely to be diagnosed with a Gleason score of greater than 6  than @entity1 with very @entity258 (p = 0.002, HR 2.4, 95% CI 1.9-3.5). Additionally, beyond 2 years on surveillance the risk of lifetime reclassification by grade and by any criteria decreased by 30% and 35% (each p <0.0001, HR 0.70, 95% CI 0.60-0.76 and HR 0.65, 95% CI 0.57-0.72, respectively) with each biopsy that showed no reclassification. CONCLUSIONS: The reclassification rate during surveillance is not equally distributed across time or risk groups. Due to misclassification at diagnosis the reclassification rate in very low and low risk groups is similar in the first 2 years but differs significantly beyond 2 years. The risk of reclassification decreases with time for each nonreclassifying biopsy beyond 2 years.
