The use of nephron-sparing intervention does not appear to be compromised after a period of active surveillance for patients with cT1 renal masses.

Introduction and objective: It remains unknown whether the use of nephron sparing intervention (NSI) is impacted with delayed intervention after a period of active surveillance (AS) compared with immediate intervention for patients with clinically localized renal masses ≤7cm (cT1RMs). We hypothesized that the proportion of patients undergoing NSI is similar among patients undergoing immediate and delayed intervention for cT1RMs.

Methods: We retrospective reviewed the prospectively maintained Michigan Urological Surgery Improvement Collaborative (MUSIC) registry for patients undergoing intervention for cT1RMs from 05/2017 to 09/2023. The primary outcome was type of treatment received: radical nephrectomy (RN) or NSI (partial nephrectomy, ablation, or stereotactic body radiation therapy). The main independent variable was timing of treatment: immediate (treatment within 90 days) vs. delayed intervention (>90 days). We fit a mixed-effects multivariable logistic regression model to assess for the adjusted association of immediate vs delayed intervention with the receipt of NSI and estimate an adjusted probability of NSI.

Results: We identified 2,156 patients, of whom 93% underwent immediate intervention and 7% underwent a period of AS prior to delayed intervention. Median time from initial visit to intervention was 1.4 (IQR 0.9-2.0) and 13 (IQR 7.7-21) months in the immediate vs delayed intervention groups, respectively. In the multivariable model, we did not appreciate a significant association between delayed intervention with receipt of NSI (OR 0.99, 95% CI 0.57-1.70, P >0.9). The adjusted proportion of NSI was 75% and 78% for patients in the immediate and delayed intervention cohorts, respectively.

Conclusion: Patients undergoing delayed intervention after AS had similar use of NSI compared with those undergoing immediate intervention. Active surveillance for patients with cT1RMs does not appear to compromise the ability to perform nephron sparing interventions.