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Active Surveillance for cystic renal masses with ≥5 years of follow-up

Login to Access Video or Poster Abstract: MP08-01
Sources of Funding: None

Introduction

We review our large singe center experience with active surveillance (AS) for cystic renal masses (CRMs), focusing on patients with ≥ 5 years (yrs) of follow-up.

Methods

We queried our prospectively maintained kidney cancer database (n = 2574) to identify patients with CRMs enrolled on AS. Estimated tumor volume (ETV) at presentation was calculated using a standard formula and linear growth rate (LGR) was evaluated. Wilcoxon rank sums were used to assess for demographic differences in growth rates and crossover to delayed intervention (DI). Kaplan-Meier curves were used to evaluate pts who crossed over to DI. A sub-set analysis was performed of patients with ≥5 years follow-up and no cross-over to DI.

Results

Of 601 AS patients, we identified 196 patients with CRMs enrolled in AS (64.3% male, median age 64.3 yrs, and mean ETV of 39.1 cm3). The median follow-up for the CRM cohort was 59.7 months. 48 patients (24%) with cystic renal masses crossed over to DI with a median time to DI of 16.7 months (IQR 10.8 - 27.7 months). When compared to solid masses, patients with CRMs (33.9% vs. 23.3%, p < 0.016) were less likely to proceed to treatment. The majority of patients (64%) with CRMs who crossed over to DI did so within 2 years. Younger patients (57.2 vs. 64.4 yrs, p < 0.001) were more likely to crossover to DI. Mean change in ETV was 5.8 cm3/yr and mean LGR was 2.6 mm/yr. Mean change in ETV of cystic masses was slower than solid masses (5.8 vs. 11.4 cm3/yr, p <0.04). A majority of patients (95.4%) were still alive at 60 months follow-up. A subset of 37 patients with CRMs had ≥5 years of follow-up without crossing over to DI. All of the patients were alive and only one patient developed distant metastasis. Mean LGR for this sub-set was 0.1 mm/yr.

Conclusions

Active surveillance with or without delayed intervention is a successful strategy in well selected patients with localized cystic renal masses. Most patients who cross over into DI are likely to do so within the first 2 years on AS. Metastasis and death are rare events in a well selected group of patients. Cystic masses grow more slowly and are less likely to proceed to intervention when compared to solid masses.

Funding

None

Authors
Andrew McIntosh
Pranav Parikh
Anthony Tokarski
Eric Ross
David Chen
Richard Greenberg
Alexander Kutikov
Marc Smaldone
Rosalia Viterbo
Robert Uzzo
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