Association among the R.E.N.A.L. nephrometry score and clinical outcomes in patients with small renal masses treated with percutaneous contrast enhanced ultrasound radiofrequency ablation

INTRODUCTION: An association between the R.E.N.A.L. nephrometry score (RNS) and clinical outcomes in patients with a small renal mass (SRM) has been proposed. We analyzed clinical outcomes according to the RNS in patients with a SRM treated with percutaneous contrast enhanced ultrasound (CEUS) radiofrequency ablation (RFA). MATERIAL AND METHODS: Patients with a SRM, who underwent RFA between January 2005 and March 2015, were retrospectively identified. The association between RNS and clinical outcomes was evaluated using parametric and non-parametric analysis. RESULTS: We analyzed 163 SRMs in 149 consecutive patients. The mean age was 71.7 years. Mean follow-up time was 33.3 months ±20.6 (2–102). The mean RNS was 5.6 ±1.52 (4–11). A total of 121 (74.2%) cases were of low complexity and 42 (25.8%) were medium complexity. We identified 11 cases of tumor persistence (6.7%). The mean RNS was 5.58 in the cases with no persistence and 5.73 in the cases with persistence (p = 0.788). We identified 15 (9.2%) cases of recurrence. The mean RNS was 5.57 ±0.1 (4–11) in the cases without recurrence and 5.73 ±0.4 (4–9) in recurrence cases (p = 0.804). Of the 76 biopsy proven RCC cases, 8 (10.5%) cases of recurrence were observed, 5 in the low complexity group and 3 in the medium complexity group (p = 0.690). A total of 9 (5.5%) cases of complications were observed, with 5 (4.3%) in the low complexity group and 4 cases in the medium complexity group (p = 0.23). The mean length of stay was 1.5 days with a significant difference between low and medium complexity groups (1.3 vs. 2.1 days, p = 0.02). The mean difference between preoperative eGFR and estimated eGFRat 12 months was -3.08 mL / min ±13.3 (-49.4–34.1) and was significant (p = 0.008).However, this variation did not show significant differences between the low and medium complexity groups (p = 0.936). All-cause mortality was 11.7%, 14 cases (11.6%) in the low complexity group and 5 (11.9%) in the medium complexity group (p = 1.0). No cases of renal cell carcinoma (RCC) specific mortality were identified. CONCLUSIONS: The RNS was not associated with tumor persistence, recurrence, cancer specific mortality, complications or renal function 12 months after the first treatment, showing significant difference only in length of hospital stay between low and medium complexity groups.