Renal functional outcomes after robot-assisted partial nephrectomy and percutaneous cryoablation of clinical T1 renal cell carcinoma - A prospective study

Abstract

Objectives: The objective of this study was to investigate renal function after robot-assisted partial nephrectomy (RAPN) and percutaneous cryoablation (PCA) in clinical stage T1 (cT1) renal cell carcinoma (RCC) and evaluate the relationship between baseline renal function and renal functional outcome.

Material and methods: Patients with cT1 RCC treated with RAPN or PCA were prospectively enrolled between June 2019 and January 2021. Renal function was evaluated using estimated glomerular filtration rate, Tc-99m diethylenetriamine-pentaacetate plasma clearance, Tc-99m mercaptoacetyltriglycine renography, and renal volume at baseline and 6 months after treatment.

Results: Fifty-six patients were included (18 RAPN, 38 PCA). PCA patients had a significantly higher age (68.5 years; P = 0.019) and Charlson comorbidity index (3.0; P = 0.007). Tumor characteristics did not differ significantly between RAPN and PCA. Total renal volume decreased significantly after PCA (-18.2 cm³; P = 0.001). Baseline chronic disease stage IIIb-IV leads to a greater reduction in renal volume (-31.8 cm³; P = 0.003) but not other renal function measures. Renal function declined significantly after either treatment without significant differences between RAPN and PCA.

Conclusion: This study found a small, similar decrease in renal function 6 months after RAPN or PCA, despite significant differences in baseline patient characteristics. Reduced renal function at baseline did not lead to a worse renal functional outcome.

Keywords: Ablation; Kidney function; Kidney neoplasms; Minimally invasive surgical procedures; nephron-sparing treatment.

Figure 1:

Diagram of the inclusion process of patients undergoing nephron-sparing RCC treatment. RCC: Renal cell carcinoma, PCA: Percutaneous cryoablation, RAPN: Robot-assisted partial nephrectomy, OPN: Open partial nephrectomy, RN: Radical nephrectomy.

Figure 2:

Boxplots of renal functional change from baseline to 6 months after RAPN and PCA. (a) Total renal volume. (b) Renal area of the tumor-bearing (ipsilateral) and non-tumor bearing (contralateral) kidneys as determined by renography. (c) eGFR. (d) DTPA-GFR. RAPN: Robotic-assisted partial nephrectomy, PCA: Percutaneous cryoablation, eGFR: Estimated glomerular filtration rate (CKD-EPI), mL/min/1.73m², DTPA-GFR: Tc-99m-diethylenetriamine pentaacetic acid clearance, mL/min/1.73m². Black dots are outliers. Gray box: Box plot of the total renal function.

Figure 3:

Illustrations of the change in median GFR from baseline to 6 months post-treatment. Color represents renal function baseline CKD-group. CKD stages defined according to KDIGO guidelines:^[26] CKD I (GFR: ³90 mL/min/1.73 m²), CKD II (GFR: 60–89 mL/min/1.73 m²), CKD IIIa (GFR: 45–59 mL/min/1.73 m²), CKD IIIb (GFR: 30–44 mL/min/1.73 m²), CKD IV (GFR: 15–29 mL/min/1.73 m²), CKD V (GFR: <15 mL/min/1.73 m²). (a) Change in DTPA GFR in patients treated with RAPN. Blue: Baseline CKD I (9 patients); red; baseline CKD II (5 patients). (b) Change in eGFR in patients treated with RAPN. Blue: Baseline CKD I (10 patients); red: Baseline CKD II (8 patients). (c) Change in DTPA GFR in patients treated with PCA. Blue: Baseline CKD I (8 patients); red: Baseline CKD II (12 patients); green: Baseline CKD IIIa (4 patients); yellow: Baseline CKD IIIb (2 patients); gray: baseline CKD IV (1 patient). (d) Change in eGFR in patients treated with PCA. Blue: Baseline CKD I (13 patients); red: Baseline CKD II (18 patients); green: Baseline CKD IIIa (2 patients); yellow: Baseline CKD IIIb (2 patients); gray: Baseline CKD IV (3 patients). GFR: Glomerular filtration rate, eGFR: Estimated glomerular filtration rate, CKD: Chronic kidney disease, DTPA GFR: Tc-99m-diethylenetriamine pentaacetic acid clearance, RAPN: Robot-assisted partial nephrectomy, PCA: Percutaneous cryoablation.