Abstract: PD59-01
Sources of Funding: National Institutes of Health (NIH), Grant Number TL1 TR001078.

Introduction

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). We sought to describe intermediate-term outcomes in patients with small renal masses enrolled in a multi-institutional, prospective study.

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. 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 and 317 (51.5%) chose active surveillance. From the active surveillance cohort, 45 (14.2%) patients underwent delayed intervention. Median follow-up time for the entire registry was 2.9 years, with 203 (33.0%) patients followed for 5 years or more. At baseline, patients who chose active surveillance were older (P < 0.001) and had higher comorbidity status (P < 0.001) than those who chose primary intervention. There was no difference in cancer-specific survival at 7 years between primary intervention and active surveillance (99.0% vs 100%, respectively, P = 0.3) [Figure 1A]. However, overall survival was higher in patients with primary intervention when compared to active surveillance at 5 years (93.0% vs 80.2%, respectively) and 7 years (91.7% vs 65.9%, respectively, P = 0.002) [Figure 1B]. The 5-year and 7-year progression-free survival rate in the active surveillance cohort was 83.9% and 71.4%, respectively.

Conclusions

In the intermediate-term, active surveillance appears to be as safe as and not inferior to primary intervention for carefully selected patients with small renal masses. As the registry matures, further studies will elucidate the effectiveness of active surveillance in the long-term.

Funding

National Institutes of Health (NIH), Grant Number TL1 TR001078.