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Deivasigamani et al. Mini-invasive Surg 2023;7:9 https://dx.doi.org/10.20517/2574-1225.2022.99 Page 9 of 19

The functional results of Robotic PN (RPN) (n = 210) and LCA (n = 226) in patients with a SRM were
studied and the RPN arm had a higher baseline eGFR (mean: 86.3 vs. 65.8; CKD ≥ 3: 12.3% vs. 44.4%). One-
month and six months proportionate eGFR decreases were comparable between RPN and LCA. New-onset
CKD has a lower prevalence in the RPN group compared to the LCA group (12.2% vs. 18.2%), while end-
stage CKD (eGFR 15 mL/min) showed a higher prevalence in the LCA group contrary to the RPN group
(4.7% vs. 0%). In view of the disparities in CKD stages and baseline GFR between the two groups, as well as
the absence of comparative analysis on tumor complexity between the groups, the observed functional
differences merit additional investigation .
[37]

Cryoablation had a significantly better renal functional outcome as compared to PN with a mean difference
of eGFR (MD: -4.5; 95%CI: -7.02 to -2.36; P < 0.001) and the PN had a creatinine rise of 0.15 (95%CI: 0.04 to
0.26; P = 0.006) in T1 renal tumor cases, proving the protected renal functional outcomes of cryoablation in
[60]
small renal masses . This finding was confirmed in a recent meta-analysis, where patients undergoing
ablation were found to have a smaller decrease in eGFR compared to PN patients (MD: -7.42; 95%CI: -13.15
to -1.70; P = 0.01) .
[61]

CA vs. other ablation technologies
Uhlig et al. . compared the renal function of CA and RFA in a meta-analysis and showed that CA
[67]
performed less well than RFA in terms of deterioration in renal function, as measured by the mean
difference in eGFR [5.82 (0.55-11.1); P = 0.03] and there was no statistically significant decline in renal
function with the mean eGFR change between CA and MWA, which was consistent with findings from
other studies. Cobelli et al. . examined the outcomes of renal function following either CA or MWA
[54]
percutaneous ablation and found no difference in renal function decrease (GFR) by creatinine levels
recorded before and after the treatment.

Functional outcome - assessment
These reviews have attempted to compare the effect on renal function of different nephron-sparing
techniques, but there have not been any head-to-head randomized comparisons that included CA, so all
studies comparing CA to other treatment modalities are inherently limited by selection bias as well as
heterogeneity in data collection and reporting. Although such studies should attempt to control for baseline
patient characteristics and tumor complexity, there is such a large difference between patients selected to
undergo PN (typically used as the method of comparison) and patients selected to undergo CA that a
significant degree of residual confounders will always remain. With the available data, cryoablation was
found to have better renal functional outcomes. Patients who have imperative indications for surgery and
cannot risk more invasive approaches could benefit from ablation therapies.

ONCOLOGICAL OUTCOMES
The primary objective of CA therapy for SRM is successful oncologic treatment in patients with confirmed
RCC. Several consensus panels have proposed standardized terminology for oncologic outcomes following
ablation therapy. “Technical success” may be determined within three months post-ablation by imaging
showing the absence of tumor enhancement and the absence of tumor expansion, and “local tumor
progression” (recurrence) is recurrent imaging evidence of new nodular enhancement in the ablation zone
or enlargement of the ablated tumor after at least one imaging study has documented adequate ablation of
the targeted SRM .
[68]