CT-guided RFA Using a Urine-Hyperexcreting Protocol in Treating Endophytic RCC: Long-term Outcomes in a Single-Arm Study

OBJECTIVES: To retrospectively assess how urine-hyperexcreting procedures influence oncologic and functional long-term outcomes of endophytic renal cell carcinomas (RCCs) treated with percutaneous radiofrequency ablation (RFA). METHODS: Between June 2014 and March 2021, 61 patients underwent CT-guided RFA to treat a histologically proven endophytic RCC. The median RENAL nephrometry score was 10 (7-11). Furosemide was intravenously injected just prior to beginning ablation cycles and normal saline was intravenously infused during RFA procedures. All were followed for 36-109 months (median, 54 months; mean, 58 months). A 5-year local tumor progression (LTP)-free survival rate was calculated with Kaplan-Meier Analysis. Estimated glomerular filtration rates (eGFR) before and after RFA were compared with a paired-t-test. The number of patients with an eGFR decreases to less than 60 mL/min/1.73m2 were assessed following RFA. The types or rates of major complication were recorded. RESULTS: A 5-year LTP-free survival rate was 96.7% (59/61). Two patients had LTP, which were treated with additional RFA or surgery. Pre-RFA and post-RFA eGFRs were 86.5±18.2 mL/min/1.73m2 and 77.0±19.5 mL/min/1.73m2, respectively (p < 0.001). Among 29 patients with eGFR of ≥ 60 & <90 mL/min/1.73m2, 8 (27.6%) had eGFRs decreased under 60 mL/min/1.73m2; none of the 26 patients with ≥90 mL/min/1.73m2 showed such a decrease. One patient had a major complication (1.6%) which was uretero-pelvic stricture. CONCLUSIONS: CT-guided RFA using a urine-hyperexcreting protocol contributes to good oncologic and acceptable functional long-term outcomes of endophytic RCCs. ADVANCES IN KNOWLEDGE: CT-guided RFA using a urine-hyperexcreting protocol has the potential to safely treat endophytic RCCs in patients with normal renal function but needs further investigation to compare diuretic group and non-diuretic or pyeloperfusion group.