Active Surveillance for Clinical Stage T1b Renal Masses

Document Type

Conference Proceeding

Publication Date

3-2025

Publication Title

European Urology

Abstract

Introduction & Objectives: Localized renal masses 4.1-7.0 cm in size (T1bRM) are typically treated with partial or radical nephrectomy.Utilization and results of initial non-surgical approaches for T1bRM are unclear. We evaluated the use of active surveillance (AS) among patients with cT1bRM across Michigan. Our objective was to assess the safety of AS for T1bRMs in the state and to determine the oncological and survival feasibility as well as rates of delayed intervention (DI).

Materials & Methods: Michigan Urological Surgery Improvement Collaborative (MUSIC) prospectively enrolls all patients with newly diagnosed RM ≤7cm. We retrospectively examined initial management and subsequent follow-up of all patients diagnosed with T1bRM between May 2017 and June 2024. Patients were stratified by type of management (intervention vs. surveillance) at 90 days following initial consultation. Patients initiating AS were further stratified as continued AS vs. delayed intervention (DI) at least 90 days after initiating AS. Results: Of 1,134 patients with T1bRM, 837 patients received immediate treatment (74%) and 297 were initiated on AS (26%). Inmultivariable analysis, predictors of AS included Charls comorbidity index ≥2 vs. 0 (OR 1.62, p=0.039), non-solid tumor type (Bosniak III/IV cyst, OR 6.62, p< 0.0001; Indeterminate, OR 5.15, p< 0.0001), and benign findings on renal mass biopsy (OR 22.2, p< 0.001). For patients completing >1 year follow up, cumulative incidence of delayed intervention was 16% at 1 year and 28% at 3 years after AS initiation. Ten T1bRM patients (3.0%) developed metastasis while on AS; of those, 1 died from RCC and 3 from other causes, 2 underwent DI and 4 remained on AS. Overall survival was 98% at one year and 92% at three years after initiating AS. In a multivariable analysis, initial AS was not associated with all-cause mortality (vs. immediate treatment, HR 1.23, p=0.5), with age as the only significant factor (HR: 1.06, p< 0.001).

Volume

87

Issue

Suppl 2

First Page

S1155

Last Page

S1155

Comments

EAU25 40th Annual EAU Congress, March 21-24, 2025 Madrid, Spain

DOI

10.1016/j.eururo.2025.09.3544

ISSN

0302-2838

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