Abstract: PD59-02
Sources of Funding: Research reported in this abstract was supported by the TL1 Predoctoral Training Program of the National Institutes of Health under award number TL1200008._x000D_ _x000D_ The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

Introduction

Active surveillance (AS) is emerging as a safe and effective strategy for the management of small renal masses, which are defined as solid masses with a maximum diameter less than 4.0cm. We conducted this prospective multi-institutional study involving patients with small renal masses in order to characterize the growth rates of these masses and their pertinence to clinical outcomes.

Methods

Beginning in 2009, the Delayed Intervention and Surveillance for Small Renal Masses (DISSRM), a prospective multi-institutional registry of patients with small renal masses, has enrolled patients who chose either primary intervention or AS. Patients electing active surveillance received regularly scheduled imaging, with tumor characteristics collected throughout their enrollment in the registry.

Results

615 patients were prospectively enrolled, of which 317 patients (51.5%) elected AS. 284 had follow-up imaging at time of this analysis, with a mean follow-up of 2.91 years. Overall mean growth rate was -0.11 cm±0.31cm/year (median: -0.07 cm/year). Growth rate and variability decreased with time, with the mean growth rates at 6, 12, 24, and 48 months of -0.10±0.09, -0.08± 0.07, -0.05±0.056, and -0.04±0.02 cm/year, respectively (Figure 1). GR was not predictive of adverse pathological features. No patient developed metastatic disease or died of kidney cancer.

Conclusions

Growth kinetics of SRM is highly variable upon entrance into AS, with both growth rate and growth rate variability decreasing with time. Early in AS, worrisome growth rates should not trigger reflex crossover to intervention as growth rates are highly variable within the first 6-12 months of surveillance. Instead we recommend re-assessment of risk stratification with additional imaging or consideration of biopsy prior to treatment. The role of GR in decision making for SRM on AS requires further refinement.

Funding

Research reported in this abstract was supported by the TL1 Predoctoral Training Program of the National Institutes of Health under award number TL1200008._x000D_ _x000D_ The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.