Percutaneous Thermal Ablation for Managing Small Renal Metastatic Tumors

Abstract

Purpose: To retrospectively evaluate the treatment outcomes of thermal ablation for renal metastatic tumors.

Materials and methods: Thirteen consecutive patients with small renal metastatic tumors (≤3 cm), who underwent thermal ablation between 2009 and 2020, were included in this study. Eight patients had extra-renal tumors during renal ablation. The primary tumors were adenoid cystic carcinoma in four patients, lung cancer in three, hemangiopericytoma in three, leiomyosarcoma in two, and thyroid cancer in one. The therapeutic effects, safety, survival rate, prognostic factor, and renal function were evaluated.

Results: We performed 18 ablation sessions (cryoablation, n = 13; radiofrequency ablation, n = 5) on 19 renal metastases with a mean diameter of 1.7 cm, which resulted in a primary technique efficacy rate of 100% without procedure-related deaths or major complications. Renal function significantly declined 6 months after ablation (P = 0.0039). During the mean follow-up period of 31.2 ± 22.4 months (range, 2.7-71.4 months), one patient had local tumor progression at 11.9 months following radiofrequency ablation. The overall survival rates at 1 and 3 years after ablation were 76.9% (95% confidence interval [CI], 54.0%-99.8%) and 59.3% (95% CI, 31.3%-87.3%), respectively. Tumor size ≥ 2 cm (P = 0.02) and metastasis from non-small cell lung cancer (P = 0.001) were significant worse prognostic factors in univariate analysis, and metastasis from non-small cell lung cancer (P = 0.01) was significant in multivariate analysis.

Conclusions: Percutaneous thermal ablation for small renal metastases is safe and feasible and can control local tumors.

Keywords: cryoablation; radiofrequency ablation; renal metastasis.

Figure 1.

Changes in renal function before and 6 months after thermal ablation. The mean eGFR was 86.4 ± 27.0 mL/min/1.73 m² (range: 34.6–128.3 mL/min/1.73 m²), and eGFR decreased significantly to 75.7 ± 25.5 mL/min/1.73 m² (range: 15.2–101.3 mL/min/1.73 m²) at 6 months after thermal ablation.

Figure 2.

Kaplan–Meier curve of the local tumor control rate after thermal ablation for renal metastasis. The local tumor control rate was 93.3% (95% confidence interval [CI], 80.7%–100%) at 1, 3, and 5 years.

Figure 3.

Kaplan–Meier curve of progression-free survival after the initial thermal ablation for renal metastasis. The progression-free survival rate was 7.7% (95% confidence interval [CI], 0%–22.2%) at 1 and 3 years.

Figure 4.

Kaplan–Meier curve of overall survival after the initial thermal ablation for renal metastasis. The median survival time was 24.3 months. The overall survival rates after renal ablation were 76.9% (95% confidence interval [CI], 54.0%–99.8%) and 59.3% (95% CI, 31.3%–87.3%) at 1 and 3 years, respectively.