Intermediate-term outcomes from the DISSRM registry: A prospective analysis of active surveillance in patients with small renal masses.

430Background: Active surveillance is an alternative to primary intervention aimed at reducing the overtreatment of small renal masses, defined as solid renal masses ≤4.0 cm (clinical stage T1a). Methods: Since 2009, the Delayed Intervention and Surveillance for Small Renal Masses (DISSRM) registry prospectively enrolled 615 patients with small renal masses who chose to undergo primary intervention or active surveillance. Intervention was recommended to patients for masses with an elevated growth rate (>0.5 cm/year) or increased tumor diameter (>4.0 cm). Primary outcomes were cancer-specific survival and overall survival; secondary outcomes included progression-free survival. Progression was strictly defined as growth rate >0.5 cm/year, greatest tumor diameter >4.0 cm, metastatic disease, or elective crossover. Outcomes were evaluated using Kaplan-Meier survival analysis and comparisons were performed using the log-rank test. Results: Of the 615 enrolled patients, 298 (48.5%) chose primary intervention an...