Percutaneous Cryoablation of T1b Renal Tumors: A Retrospective Evaluation of Local Tumor Control, Renal Function Preservation, Adverse Events and Ablation Margins in 80 Patients.

Abstract

Purpose: This retrospective study investigates the long-term efficacy and safety of percutaneous cryoablation (PCA) for the treatment of clinical T1b renal masses (RMs) over a minimum follow-up of two years. The primary hypothesis is that achieving an intraprocedural ice-ball margin of ≥8 mm during PCA of T1b renal cell carcinoma (RCC) results in superior local tumor control without increasing adverse events.

Materials and methods: Eighty consecutive patients with biopsy-proven T1b RCC (tumor size 4.1-7.0 cm) were treated with CT-guided PCA between 2019 and 2023 at a single center. Outcomes assessed included local tumor progression-free survival (LTPFS), change in renal function (eGFR), and adverse events per Society of Interventional Radiology (SIR) criteria. Ice-ball margins were categorized as <8 mm versus ≥8 mm. Kaplan-Meier survival curves and log-rank tests were used for statistical analysis, with significance set at p < 0.05.

Results: Primary efficacy was 95% (76/80), while secondary efficacy reached 98.8% (79/80) after retreatment of four local recurrences. The 24-month LTPFS was 98.8%. Patients with an ice-ball margin ≥8 mm showed superior 24-month local control (100%) compared to those with 5-<8 mm margins (57% at 6 months; p = 0.002). Mean eGFR declined slightly by -2 mL/min/1.73 m² (p = 0.125). No SIR Grade 3 or higher adverse events reported.

Conclusion: PCA is a safe, effective, and nephron-sparing treatment for T1b RCC. Achieving an ice-ball margin ≥8 mm significantly reduces residual disease and early recurrence.