Split renal function after treatment of small renal masses: comparison between radiofrequency ablation and laparoscopic partial nephrectomy

BACKGROUND: Radiofrequency ablation (RFA) and laparoscopic partial nephrectomy (LPN) are used to treat small renal masses (SRM; ≤4 cm), although there are conflicting results in the changes in creatinine and estimated glomerular filtration rate (eGFR) after treatment. On contrast-enhanced computed tomography (CE-CT) images, the quantity and quality of renal function can be evaluated by calculating the split renal function (SRF). PURPOSE: To compare renal function after RFA or LPN treatment of SRMs through evaluation of the SRF in the affected kidney. MATERIAL AND METHODS: Single T1a renal tumors successfully treated with RFA (n = 60) or LPN (n = 31) were retrospectively compared. The SRF was calculated on pre-treatment CE-CT images and the first follow-up exam after completed treatment. Serum creatinine and eGFR values were collected simultaneously. To compare renal function outcomes, Student’s t-test and multivariable linear regression models (adjusted to RFA/LPN treatment, pre-treatment SRF/eGFR, BMI, age, tumor characteristics, and Charlson Comorbidity Index) were used. RESULTS: SRF was reduced in both groups, although reduction was greater in the LPN group (LPN –5.7%) than in the RFA group (RFA –3.5%; P = 0.013). After adjusted analysis, the LPN group still had greater SRF reduction (difference 3.2%, 95% confidence interval 1.3–1.5; P = 0.001). There was no difference between groups in the change of creatinine/eGFR after treatment. CONCLUSION: Both RFA and LPN are nephron-sparing when treating SRMs. However, in this series, reduction of SRF in the affected kidney was smaller after RFA, having a more favorable preservation of renal function than LPN.