Every decade counts: a narrative review of functional recovery after partial nephrectomy

Parenchymal obliteration by renal masses: Functional and oncologic implications

OBJECTIVES

Most renal tumors merely displace nephrons while others can obliterate parenchyma in an invasive manner. Substantial parenchymal volume replacement (PVR) by renal cell carcinoma (RCC) may have oncologic implications; however, studies regarding PVR remain limited. Our objective was to evaluate the oncologic implications associated with PVR using improved methodology including more accurate and objective tools.

PATIENTS/METHODS

A total of 1,222 patients with non-metastatic renal tumors managed with partial nephrectomy (PN) or radical nephrectomy (RN) at Cleveland Clinic (2011-2014) with necessary studies were retrospectively evaluated. Parenchymal volume analysis via semiautomated software was used to estimate split renal function and preoperative parenchymal volumes. Using the contralateral kidney as a control, %PVR was defined: (parenchymal volumecontralateral-parenchymal volumeipsilateral) normalized by parenchymal volumecontralateral x100%. PVR was determined preoperatively and not altered by management. Patients were grouped by degree of PVR: minimal (<5%, N = 566), modest (5%-25%, N = 414), and prominent (≥25%, N = 142). Kaplan-Meier was used to evaluate survival outcomes relative to degree of PVR. Multivariable Cox-regression models evaluated predictors of recurrence-free survival (RFS).

RESULTS

Of 1,122 patients, 801 (71%) were selected for PN and 321 (29%) for RN. Overall, median tumor size was 3.1 cm and 6.8 cm for PN and RN, respectively, and median follow-up was 8.6 years. Median %PVR was 15% (IQR = 6%-29%) for patients selected for RN and negligible for those selected for PN. %PVR correlated inversely with preoperative ipsilateral GFR (r = -0.49, P < 0.01) and directly with advanced pathologic stage, high tumor grade, clear cell histology, and sarcomatoid features (all P < 0.01). PVR≥25% associated with shortened recurrence-free, cancer-specific, and overall survival (all P < 0.01). Male sex, ≥pT3a, tumor grade 4, positive surgical margins, and PVR≥25% independently associated with reduced RFS (all P < 0.02).

CONCLUSIONS

Obliteration of normal parenchyma by RCC substantially impacts preoperative renal function and patient selection. Our data suggests that increased PVR is primarily driven by aggressive tumor characteristics and independently associates with reduced RFS, although further studies will be needed to substantiate our findings.

Parenchymal volume preservation during partial nephrectomy: improved methodology to assess impact and predictive factors

OBJECTIVE

To rigorously evaluate the impact of the percentage of parenchymal volume preserved (PPVP) and how well the preserved parenchyma recovers from ischaemia (Recischaemia) on functional outcomes after partial nephrectomy (PN) using an accurate and objective software-based methodology for estimating parenchymal volumes and split renal function (SRF). A secondary objective was to assess potential predictors of the PPVP.

PATIENTS AND METHODS

A total of 894 PN patients with available studies (2011-2014) were evaluated. The PPVP was measured from cross-sectional imaging at ≤3 months before and 3-12 months after PN using semi-automated software. Pearson correlation evaluated relationships between continuous variables. Multivariable linear regression evaluated predictors of ipsilateral glomerular filtration rate (GFR) preserved and the PPVP. Relative-importance analysis was used to evaluate the impact of the PPVP on ipsilateral GFR preserved. Recischaemia was defined as the percentage of ipsilateral GFR preserved normalised by the PPVP.

RESULTS

The median tumour size and R.E.N.A.L. nephrometry score were 3.4 cm and 7, respectively. In all, 49 patients (5.5%) had a solitary kidney. In all, 538 (60%)/251 (28%)/104 (12%) patients were managed with warm/cold/zero ischaemia, respectively. The median pre/post ipsilateral GFRs were 40/31 mL/min/1.73 m2, and the median (interquartile range [IQR]) percentage of ipsilateral GFR preserved was 80% (71-88%). The median pre/post ipsilateral parenchymal volumes were 181/149 mL, and the median (IQR) PPVP was 84% (76-92%). In all, 330 patients (37%) had a PPVP of <80%, while only 34 (4%) had a Recischaemia of <80%. The percentage of ipsilateral GFR preserved correlated strongly with the PPVP (r = 0.83, P < 0.01) and loss of parenchymal volume accounted for 80% of the loss of ipsilateral GFR. Multivariable analysis confirmed that the PPVP was the strongest predictor of ipsilateral GFR preserved. Greater tumour size and endophytic and nearness properties of the R.E.N.A.L. nephrometry score were associated with a reduced PPVP (all P ≤ 0.01). Solitary kidney and cold ischaemia were associated with an increased PPVP (all P < 0.05).

CONCLUSIONS

A reduced PPVP predominates regarding functional decline after PN, although a low Recischaemia can also contribute. Tumour-related factors strongly influence the PPVP, while surgical efforts can improve the PPVP as observed for patients with solitary kidneys.

Off-clamp Versus On-clamp Partial Nephrectomy: Re-envision of a Dilemma

We contextualize controversial evidence on the impact of warm ischemia on functional outcomes after partial nephrectomy for localized renal tumors and provide a holistic framework for re-envisioning the dilemma of off-clamp versus on-clamp surgery. The focus should shift away from the surgeon towards patient- and kidney-related characteristics.

Development and internal validation of a nomogram predicting 3-year chronic kidney disease upstaging following robot-assisted partial nephrectomy

PURPOSE

Aim of the present study was to develop and validate a nomogram to accurately predict the risk of chronic kidney disease (CKD) upstaging at 3 years in patients undergoing robot-assisted partial nephrectomy (RAPN).

METHODS

A multi-institutional database was queried to identify patients treated with RAPN for localized renal tumor (cT1-cT2, cN0, cM0). Significant CKD upstaging (sCKD-upstaging) was defined as development of newly onset CKD stage 3a, 3b, and 4/5. Model accuracy was calculated according to Harrell C-index. Subsequently, internal validation using bootstrapping and calibration was performed. Then nomogram was depicted to graphically calculate the 3-year sCKD-upstaging risk. Finally, regression tree analysis identified potential cut-offs in nomogram-derived probability. Based on this cut-off, four risk classes were derived with Kaplan-Meier analysis tested this classification.

RESULTS

Overall, 965 patients were identified. At Kaplan-Meier analysis, 3-year sCKD-upstaging rate was 21.4%. The model included baseline (estimated glomerular filtration rate) eGFR, solitary kidney status, multiple lesions, R.E.N.A.L. nephrometry score, clamping technique, and postoperative acute kidney injury (AKI). The model accurately predicted 3-year sCKD-upstaging (C-index 84%). Based on identified nomogram cut-offs (7 vs 16 vs 26%), a statistically significant increase in sCKD-upstaging rates between low vs intermediate favorable vs intermediate unfavorable vs high-risk patients (1.3 vs 9.2 vs 22 vs 54.2%, respectively, p < 0.001) was observed.

CONCLUSION

Herein we introduce a novel nomogram that can accurately predict the risk of sCKD-upstaging at 3 years. Based on this nomogram, it is possible to identify four risk categories. If externally validated, this nomogram may represent a useful tool to improve patient counseling and management.

Thermal Ablation Versus Partial Nephrectomy for cT1 Renal Mass in a Solitary Kidney: A Matched Cohort Comparative Analysis

BACKGROUND

Nephron-sparing approaches are preferred for renal mass in a solitary kidney (RMSK), with partial nephrectomy (PN) generally prioritized. Thermal ablation (TA) also is an option for small renal masses in this setting; however, comparative functional/survival outcomes are not well-defined.

METHODS

A retrospective study of 504 patients (1975-2022) with cT1 RMSK managed with PN (n = 409)/TA (n = 95) with necessary data for analysis was performed. Propensity score was used for matching patients, including age, preoperative glomerular filtration rate (GFR), tumor diameter, R.E.N.A.L. ((R)adius (tumor size as maximal diameter), (E)xophytic/endophytic properties of tumor, (N)earness of tumor deepest portion to collecting system or sinus, (A)nterior (a)/posterior (p) descriptor, and (L)ocation relative to polar lines), and comorbidities. Functional outcomes were compared, and Kaplan-Meier was used to analyze survival.

RESULTS

The matched cohort included 132 patients (TA = 66/PN = 66), with median tumor diameter of 2.4 cm, R.E.N.A.L. of 6, and preoperative GFR of 52 ml/min/1.73 m2. Acute kidney injury occurred in 11%/61% in the TA/PN cohorts, respectively (p < 0.01). After recovery, median GFR preserved was 89%/83% for TA/PN, respectively (p = 0.02), and 5-year dialysis-free survival was 96% in both cohorts. Median follow-up was 53 months. Five-year recurrence-free survival (RFS) was 62%/86% in the TA/PN cohorts, respectively (p < 0.01). Five-year local recurrence (LR)-free survival was 74%/95% in the TA/PN cohorts, respectively (p < 0.01). Five-year cancer-specific survival (CSS) was 96%/98% in the TA/PN cohorts, respectively (p = 0.7). Local recurrence was observed in nine of 36 (25%) and five of 30 (17%) patients managed with laparoscopic versus percutaneous TA, respectively. For TA with LR (n = 14), nine patients presented with multifocality and/or cT1b tumors. Twelve LR were managed with salvage TA, and seven remained cancer-free, while five developed systemic recurrence, three with concomitant LR.

CONCLUSIONS

Functional outcomes for TA for RMSK were improved compared with PN. Local recurrence was more common after TA and often was associated with the laparoscopic approach, multifocality, and large tumor size. Improved patient selection and greater experience with TA should improve outcomes. Salvage of LR was not always possible. Partial nephrectomy remains the reference standard for RMSK.

Incidence, risk factors, and significance of 20% decrease from new baseline estimated glomerular filtration rate after radical and partial nephrectomy within 2 years

OBJECTIVES

To evaluate the incidence and risk factors of a 20% decrease from new baseline (NB)-estimated glomerular filtration rate (eGFR) within 2 years after radical nephrectomy (RN) and partial nephrectomy (PN) and to examine the difference in the incidence of end-stage renal disease (ESRD) with or without the 20% decrease.

METHODS

This retrospective study included 238 patients undergoing RN and 369 undergoing PN for cT1a-cT3a renal cancer. The incidence of a 20% decrease from NB-eGFR within 2 years after RN/PN was examined and its potential risk factors including surgery type were assessed by multivariate logistic regression analysis. The development of ESRD was analyzed as an endpoint and its incidence was compared according to the presence or absence of the 20% decrease from NB-eGFR within 2 years.

RESULTS

Overall, the 20% decrease from NB-eGFR within 2 years was observed in 37 patients (6.1%), including 10 (4.2%) and 27 (7.3%) after RN and PN, respectively (p = 0.117). Diabetes mellitus, proteinuria, and perioperative complications were shown to be independent risk factors for the 20% decrease from NB-eGFR, while surgery type was not. During the median follow-up of 65 months, the ESRD-free survival rate at 6 years was 75.5% and 99.6% in patients with and without the 20% decrease from NB-eGFR, respectively (p < 0.001), while no significant difference was observed between patients undergoing RN and PN (98.1% and 98.7%, p = 0.561).

CONCLUSIONS

Because the incidence of ESRD after the 20% decrease from NB-eGFR within 2 years was as high as 24.5% at 6 years, these patients should be followed with utmost care.

Practical Prediction of New Baseline Renal Function After Partial Nephrectomy

BACKGROUND

Partial nephrectomy (PN) is generally preferred for localized renal masses due to strong functional outcomes. Accurate prediction of new baseline glomerular filtration rate (NBGFR) after PN may facilitate preoperative counseling because NBGFR may affect long-term survival, particularly for patients with preoperative chronic kidney disease. Methods for predicting parenchymal volume preservation, and by extension NBGFR, have been proposed, including those based on contact surface area (CSA) or direct measurement of tissue likely to be excised/devascularized during PN. We previously reported that presuming 89% of global GFR preservation (the median value saved from previous, independent analyses) is as accurate as the more subjective/labor-intensive CSA and direct measurement approaches. More recently, several promising complex/multivariable predictive algorithms have been published, which typically include tumor, patient, and surgical factors. In this study, we compare our conceptually simple approach (NBGFRPost-PN = 0.90 × GFRPre-PN) with these sophisticated algorithms, presuming that an even 90% of the global GFR is saved with each PN.

PATIENTS AND METHODS

A total of 631 patients with bilateral kidneys who underwent PN at Cleveland Clinic (2012-2014) for localized renal masses with available preoperative/postoperative GFR were analyzed. NBGFR was defined as the final GFR 3-12 months post-PN. Predictive accuracies were assessed from correlation coefficients (r) and mean squared errors (MSE).

RESULTS

Our conceptually simple approach based on uniform 90% functional preservation had equivalent r values when compared with complex, multivariable models, and had the lowest degree of error when predicting NBGFR post-PN.

CONCLUSIONS

Our simple formula performs equally well as complex algorithms when predicting NBGFR after PN. Strong anchoring by preoperative GFR and minimal functional loss (≈ 10%) with the typical PN likely account for these observations. This formula is practical and can facilitate counseling about expected postoperative functional outcomes after PN.

Functional recovery after partial nephrectomy in a solitary kidney

OBJECTIVES

Partial nephrectomy (PN) is the reference standard for renal mass in a solitary kidney (RMSK), although factors determining functional recovery in this setting remain poorly defined.

PATIENTS/METHODS

Single center, retrospective analysis of 841 RMSK patients (1975-2022) managed with PN with functional data, including 361/435/45 with cold/warm/zero ischemia, respectively. A total of 155 of these patients also had necessary studies for detailed analysis of parenchymal volume preserved. Acute kidney injury (AKI) was classified by RIFLE (Risk/Injury/Failure/Loss/Endstage). Recovery-from-ischemia (Rec-Ischemia) was defined as glomerular filtration rate (GFR) saved normalized by parenchymal volume saved. Logistic regression identified predictive factors for AKI and predictors of Rec-Ischemia were analyzed by multivariable linear regression.

RESULTS

Overall, median preoperative GFR was 56.7 ml/min/1.73m2 and new-baseline and 5-year GFRs were 43.1 and 44.5 ml/min/1.73m2, respectively. Median follow-up was 55 months; 5-year dialysis-free survival was 97%. In the detailed analysis cohort, a primary focus of this study, median warm (n = 70)/cold (n = 85) ischemia times were 25/34 minutes, respectively; and median preoperative, new-baseline and 5-year GFRs were 57.8, 45.0, and 41.7 ml/min/1.73m2, respectively. Functional recovery correlated strongly with parenchymal volume preserved (r = 0.84, p < 0.001). Parenchymal volume loss accounted for 69% of the total median GFR decline associated with PN, leaving only 3 to 4 ml/min/1.73m2 attributed to ischemia and other factors. AKI occurred in 52% of patients and the only independent predictor of AKI was ischemia time. Independent predictors of reduced Rec-Ischemia were increased age, warm ischemia, and AKI.

CONCLUSION

The main determinant of functional recovery after PN in RMSK is parenchymal volume preservation. Type/duration of ischemia, AKI, and age also correlated, although altogether their contributions were less impactful. Our findings suggest multiple opportunities for optimizing functional outcomes although preservation of parenchymal volume remains predominant. Long-term function generally remains stable with dialysis only occasionally required.

Retroperitoneoscopic Clampless, Sutureless Hybrid Therapy in the Management of Renal Hilar Tumors

OBJECTIVE

We aimed to investigate the outcomes and feasibility of a retroperitoneoscopic clampless, sutureless hybrid technique in the management of renal hilar tumors.

METHODS

A retrospective cohort of consecutive patients with renal hilar tumors who received retroperitoneoscopic clampless, sutureless hybrid therapy between January 2017 and April 2021 was included. The hybrid surgical technique involved microwave ablation (MWA), followed by clampless tumor enucleation and sutureless hemostasis. Surgical, pathological, and oncological outcomes were recorded and analyzed.

RESULTS

Sixty patients were included in this study. The median tumor size was 3.5 cm (2-5), the median RENAL score was 7 (range 6-10), the median operative time was 110 min (70-130), and the median estimated blood loss was 80 mL (30-130). The median length of postoperative hospital stay was 3 days (2-4), and no warm ischemia time was observed, except in one patient who required conversion to conventional on-clamp laparoscopic partial nephrectomy (LPN) with a 10 min warm ischemia time. Three minor complications (Clavien-Dindo grade I) and one major complication (Clavien-Dindo grade III) were recorded postoperatively. Thus far, no blood transfusions have been required. Renal dysfunction or tumor recurrence did not occur within a median follow-up of 45 months.

CONCLUSION

The retroperitoneoscopic hybrid technique involving MWA, clampless tumor enucleation, and sutureless hemostasis is a feasible and safe option for the management of selective renal hilar tumors. Complete tumor removal with maximal renal function preservation can be achieved, with a low complication rate.

Parenchymal volume analysis to assess longitudinal functional decline following partial nephrectomy

OBJECTIVE

To identify factors associated with longitudinal ipsilateral functional decline after partial nephrectomy (PN).

PATIENTS AND METHODS

Of 1140 patients managed with PN (2012-2014), 349 (31%) had imaging/serum creatinine levels pre-PN, 1-12 months post-PN (new baseline), and >3 years later necessary for inclusion. Parenchymal-volume analysis was used to determine split renal function. Patients were grouped as having significant renal comorbidity (CohortSRC : diabetes mellitus with insulin-dependence or end-organ damage, refractory hypertension, or severe pre-existing chronic kidney disease) vs not having significant renal comorbidity (CohortNoSRC ) preoperatively. Multivariable regression was used to identify predictors of annual ipsilateral parenchymal atrophy and functional decline relative to new baseline values post-PN, after the kidney had healed.

RESULTS

The median follow-up was 6.3 years with 87/226/36 patients having cold/warm/zero ischaemia. The median cold/warm ischaemia times were 32/22 min. Overall, the median tumour size was 3.0 cm. The preoperative glomerular filtration rate (GFR) and new baseline GFR (NBGFR) were 81 and 71 mL/min/1.73 m2 , respectively. After establishment of the NBGFR, the median loss of global and ipsilateral function was 0.7 and 0.4 mL/min/1.73 m2 /year, respectively, consistent with the natural ageing process. Overall, the median ipsilateral parenchymal atrophy was 1.2 cm3 /year and accounted for a median of 53% of the annual functional decline. Significant renal comorbidity, age, and warm ischaemia were independently associated with ipsilateral parenchymal atrophy (all P < 0.01). Significant renal comorbidity and ipsilateral parenchymal atrophy were independently associated with annual ipsilateral functional decline (both P < 0.01). Annual median ipsilateral parenchymal atrophy and functional decline were both significantly increased for CohortSRC compared to CohortNoSRC (2.8 vs 0.9 cm3 , P < 0.01 and 0.90 vs 0.30 mL/min/1.73 m2 /year, P < 0.01, respectively).

CONCLUSIONS

Longitudinal renal function following PN generally follows the normal ageing process. Significant renal comorbidities, age, warm ischaemia, and ipsilateral parenchymal atrophy were the most important predictors of ipsilateral functional decline following establishment of NBGFR.

Risks and benefits of partial nephrectomy performed with limited or with zero ischaemia time

OBJECTIVE

To test the hypothesis that longer warm ischaemia time (WIT) might have a marginal impact on renal functional outcomes and might, in fact, reduce haemorrhagic risk intra-operatively.

PATIENTS AND METHODS

Data from 1140 patients treated with elective partial nephrectomy (PN) for a cT1-2 cN0 cM0 renal mass were prospectively collected. WIT was defined as the duration of clamping of the main renal artery with no refrigeration and was tested as a continuous variable. The primary outcome of the study was evaluation of the effect of WIT on renal function (estimated glomerular filtration rate [eGFR]) postoperatively, at 6 months and in the long term (measured between 1 and 5 years after surgery). The secondary outcome of the study was haemorrhagic risk, defined as estimated blood loss (EBL) or peri-operative transfusions. Multivariable linear, logistic and Cox regression analyses, accounting for age, Charlson comorbidity index, clinical size, preoperative eGFR and year of surgery, were used and the potential nonlinear relationship between WIT and the study outcomes was modelled using restricted cubic splines.

RESULTS

A total of 863 patients (76%) underwent PN with WIT and 277 (24%) without. The baseline median eGFR was 87.3 (68.8-99.2) mL/min/1.73m2 for the on-clamp population and 80.6 (63.2-95.2) mL/min/1.73m2  for the off-clamp population. The median duration of WIT was 17 (13-21) min. At multivariable analyses predicting renal function, longer WIT was associated with decreased postoperative eGFR (estimate: -0.21, 95% confidence interval [CI] -0.31; -0.11 [P < 0.001]). Conversely, no association between WIT and eGFR was recorded at 6-month or long-term follow-up (all P > 0.8). At multivariable analyses predicting haemorrhagic risk, clampless resection with no ischaemia time and PN with short WIT was associated with an increased EBL (estimate: -21.56, 95% CI -28.33; -14.79 [P < 0.001]) and peri-operative transfusion rate (estimate: -0.009, 95% CI -0.01; -0.003 [P = 0.002]). No association between WIT and positive surgical margin status was recorded (all P = 0.1).

CONCLUSION

Patients and clinicians should be aware that performing PN with very limited or even with zero WIT might increase bleeding and the need for peri-operative transfusion while not improving long-term renal function outcomes.

Laparoscopic aspirator bracket: a new instrument facilitating the aspiration and exposure of operative field simultaneously in laparoscopic nephron-sparing surgery

Background

This study aims to describe a novel laparoscopic aspirator bracket (LAB) and its use in laparoscopic nephron-sparing surgery (NSS) by a simple enucleation (SE) technique.

Methods

A total of 123 renal tumor cases who underwent laparoscopic NSS via LAB or laparoscopic aspirator between July 2017 and April 2021 were retrospectively analyzed. General characteristics, perioperative data and postoperative follow-up data of patients were compared.

Results

The application of LAB in laparoscopic renal tumor SE surgery shortened the operation time (88.58 ± 38.25 vs. 102.25 ± 35.84 min, p < 0.05) and improved the zero ischemia rate (18.75% vs. 3.39%, p < 0.05), shortened warm ischemia time (16.17 ± 5.16 vs. 19.39 ± 5.62 min, p < 0.05) and decreased intraoperative blood loss (166.19 ± 111.60 vs. 209.15 ± 127.10 ml, p < 0.05). In addition, the serum creatinine and eGFR values in the LAB group also showed faster and better renal function recovery.

Conclusion

The new LAB could aspirate and expose the operative field with a single instrument. In operations that need to expose and aspirate simultaneously, such as in renal tumor simple enucleation, it could shorten operation time, reduce intraoperative blood loss and improve the postoperative renal function recovery.

Functional recovery after partial nephrectomy: next generation analysis

OBJECTIVES

To provide a more rigorous assessment of factors affecting functional recovery after partial nephrectomy (PN) using novel tools that allow for analysis of more patients and improved accuracy for assessment of parenchymal volume loss, thereby revealing the potential impact of secondary factors such as ischaemia.

PATIENTS AND METHODS

Of 1140 patients managed with PN (2012-2014), 670 (59%) had imaging and serum creatinine levels measured before and after PN necessary for inclusion. Recovery from ischaemia was defined as the ipsilateral glomerular filtration rate (GFR) saved normalised by parenchymal volume saved. Acute kidney injury was assessed through Spectrum Score, which quantifies the degree of acute ipsilateral renal dysfunction due to exposure to ischaemia that would otherwise be masked by the contralateral kidney. Multivariable regression was used to identify predictors of Spectrum Score and Recovery from Ischaemia.

RESULTS

In all, 409/189/72 patients had warm/cold/zero ischaemia, respectively, with median (interquartile range [IQR]) ischaemia times for cold and warm ischaemia of 30 (25-42) and 22 (18-28) min, respectively. The median (IQR) global preoperative GFR and new baseline GFR (NBGFR) were 78 (63-92) and 69 (54-81) mL/min/1.73 m2 , respectively. The median (IQR) ipsilateral preoperative GFR and NBGFR were 40 (33-47) and 31 (24-38) mL/min/1.73 m2 , respectively. Functional recovery correlated strongly with parenchymal volume preserved (r = 0.83, P < 0.01). The median (IQR) decline in ipsilateral GFR associated with PN was 7.8 (4.5-12) mL/min/1.73 m2 with loss of parenchyma accounting for 81% of this loss. The median (IQR) recovery from ischaemia was similar across the cold/warm/zero ischaemia groups at 96% (90%-102%), 95% (89%-101%), and 97% (91%-102%), respectively. Independent predictors of Spectrum Score were ischaemia time, tumour complexity, and preoperative global GFR. Independent predictors of recovery from ischaemia were insulin-dependent diabetes mellitus, refractory hypertension, warm ischaemia, and Spectrum Score.

CONCLUSIONS

The main determinant of functional recovery after PN is parenchymal volume preservation. A more robust and rigorous evaluation allowed us to identify secondary factors including comorbidities, increased tumour complexity, and ischaemia-related factors that are also independently associated with impaired recovery, although altogether these were much less impactful.

Selective Use of Neoadjuvant Targeted Therapy Is Associated with Greater Achievement of Partial Nephrectomy for High-complexity Renal Masses in a Solitary Kidney

Background

Partial nephrectomy (PN) is preferred for a renal mass in a solitary kidney (RMSK), although tumors with high complexity can be challenging.

Objective

To evaluate the evolution of RMSK management with a focus on achievement of PN.

Design setting and participants

Patients with nonmetastatic RMSK (n = 499) were retrospectively reviewed; 133 had high tumor complexity, including 80 in the pre-tyrosine kinase inhibitor (TKI) era (1999-2008) and 53 in the TKI era (2009-2022). After 2009, 23/53 patients received neoadjuvant TKI and 30/53 had immediate-surgery.

Outcome measurements and statistical analysis

Functional outcomes, adverse events and complications, dialysis-free survival, and recurrence-free survival (RFS) were the measures evaluated. Mann-Whitney and χ2 tests were used to compare cohorts, and the log-rank test was applied for survival analyses.

Results and limitations

Overall, the median RENAL score was 10 and the median tumor diameter was 5.2 cm. Demographic characteristics, tumor diameter, and RENAL scores were similar between the pre-TKI-era and TKI-era groups. In the TKI era, 23/53 patients (43%) with clear-cell histology were selected for neoadjuvant TKI. These 23 patients had a greater median tumor diameter (7.1 vs 4.4 cm; p = 0.02) and RENAL score (11 vs 10; p = 0.07). After TKI treatment, the median tumor diameter decreased to 5.6 cm and the RENAL score to 9, and tumor volume was reduced by 59% (all p < 0.05). PN was accomplished in 21/23 (91%) the TKI-treated cases and in 27/30 (90%) of the immediate-surgery cases (2009-2022). PN was only accomplished in 52/80 (65%) of the patients from the pre-TKI era (p < 0.01). The 5-yr dialysis-free survival rate was 59% in the pre-TKI-era group and 91% in the TKI-era group. The 5-yr RFS rate was lower in the TKI-era group (59% vs 74%; p = 0.21), which was mostly related to more aggressive tumor biology, as reflected by a predominance of systemic rather than local recurrences.

Conclusions

Management of RMSK with high tumor complexity is challenging. Selective use of TKI therapy was associated with greater use of PN, although a randomized study is needed. RFS mostly reflected aggressive tumor biology rather than failure of local management.

Patient summary

For complex kidney tumors in patients with a single kidney, management is challenging. Use of drugs called tyrosine kinase inhibitors before surgery was associated with reductions in tumor size and greater ability to achieve partial kidney removal for cancer control. Most recurrences were metastatic, which reflects aggressive tumor biology rather than failure of surgery.

New-onset Chronic Kidney Disease After Surgery for Localised Renal Masses in Patients with Two Kidneys and Preserved Renal Function: A Contemporary Multicentre Study

Background

There is a lack of evidence on acute kidney injury (AKI) and new-onset chronic kidney disease (CKD) after surgery for localised renal masses (LRMs) in patients with two kidneys and preserved baseline renal function.

Objective

To evaluate the prevalence and risk of AKI and new-onset clinically significant CKD (csCKD) in patients with a single renal mass and preserved renal function after being treated with partial (PN) or radical (RN) nephrectomy.

Design setting and participants

We queried our prospectively maintained databases to identify patients with a preoperative estimated glomerular filtration rate (eGFR) of ≥60 ml/min/1.73 m² and a normal contralateral kidney who underwent PN or RN for a single LRM (cT1-T2N0M0) between January 2015 and December 2021 at four high-volume academic institutions.

Intervention

PN or RN.

Outcome measurements and statistical analysis

The outcomes of this study were AKI at hospital discharge and the risk of new-onset csCKD, defined as eGFR <45 ml/min/1.73 m², during the follow-up. Kaplan-Meier curves were used to examine csCKD-free survival according to tumour complexity. A Multivariable logistic regression analysis assessed the predictors of AKI, while a multivariable Cox regression analysis assessed the predictors of csCKD. Sensitivity analyses were performed in patients who underwent PN.

Results and limitations

Overall, 2469/3076 (80%) patients met the inclusion criteria. At hospital discharge, 371/2469 (15%) developed AKI (8.7% vs 14% vs 31% in patients with low- vs intermediate- vs high-complexity tumours, p < 0.001). At the multivariable analysis, body mass index, history of hypertension, tumour complexity, and RN significantly predicted the occurrence of AKI. Among 1389 (56%) patients with complete follow-up data, 80 events of csCKD were recorded. The estimated csCKD-free survival rates were 97%, 93% and 86% at 12, 36, and 60 mo, respectively, with significant differences between patients with high- versus low-complexity and high- versus intermediate-complexity tumours (p = 0.014 and p = 0.038, respectively). At the Cox regression analysis, age-adjusted Charlson Comorbidity Index, preoperative eGFR, tumour complexity, and RN significantly predicted the risk of csCKD during the follow-up. The results were similar in the PN cohort. The main limitation of the study was the lack of data on eGFR trajectories within the 1st year after surgery and on long-term functional outcomes.

Conclusions

The risk of AKI and de novo csCKD in elective patients with an LRM and preserved baseline renal function is not clinically negligible, especially in those with higher-complexity tumours. While baseline nonmodifiable patient/tumour-related characteristics modulate this risk, PN should be prioritised over RN to maximise nephron preservation if oncological outcomes are not jeopardised.

Patient summary

In this study, we evaluated how many patients with a localised renal mass and two functioning kidneys, who were candidates for surgery at four referral European centres, experienced acute kidney injury at hospital discharge and significant renal functional impairment during the follow-up. We found that the risk of acute kidney injury and clinically significant chronic kidney disease in this patient population is not negligible, and was associated with specific baseline patient comorbidities, preoperative renal function, tumour anatomical complexity, and surgery-related factors, in particular the performance of radical nephrectomy.

Limited non-linear impact of warm ischemia time on renal functional decline after partial nephrectomy: a propensity score-matched study

OBJECTIVE

To quantificationally illustrate the impact of ischemia time (IT) on renal function decline after partial nephrectomy (PN), especially for patients with compromised baseline renal function (estimated glomerular filtration rate [eGFR] < 90 mL/min/1.73 m²).

METHODS

Patients undergoing PN during 2014-2021 from a prospectively maintained database were reviewed. Propensity score matching (PSM) was employed to balance the possible covariates between patients with or without baseline compromised renal function. Specifically, the relationship of IT with postoperative renal function was illustrated. Two machine learning methods (logistic least absolute shrinkage and selection operator [LASSO] logistic regression and random forest) were applied to quantify the relative impact of each covariables.

RESULTS

The average drop percent of eGFR was -10.9% (- 12.2%, - 9.0%). Multivariable Cox proportional regression and linear regression analyses identified five risk factors for renal function decline, namely RENAL Nephrometry Score (RNS), age, baseline eGFR, diabetes and IT (all p < 0.05). Specifically, the relationship of IT with postoperative functional decline emerged as non-linear, with an increase from 10-30 min and a plateau afterwards among patients with normal function (eGFR ≥ 90 mL/min/1.73 m²), whereas with an increase from 10 to 20 min and a plateau afterwards among patients with compromised function (eGFR < 90 mL/min/1.73 m²). Furthermore, the coefficient's path and random forest analysis revealed that the top two most important features were RNS and age.

CONCLUSION

IT exhibits the secondarily non-linear relationship with postoperative renal function decline. Patients with compromised baseline renal function are less tolerant to ischemia damage. The use of a single cut-off interval of IT in the setting of PN is flawed.

Long-Term Renal Function Following Renal Cancer Surgery: Historical Perspectives, Current Status, and Future Considerations

Knowledge of functional recovery after partial (PN) and radical nephrectomy for renal cancer has advanced considerably, with PN now established as the reference standard for most localized renal masses. However, it is still unclear whether PN provides an overall survival benefit in patients with a normal contralateral kidney. While early studies seemingly demonstrated the importance of minimizing warm-ischemia time during PN, multiple new investigations over the last 10 years have proven that parenchymal mass lost is the most important predictor of new baseline renal function. Minimizing loss of parenchymal mass during resection and reconstruction is the most important controllable aspect of long-term post-operative renal function preservation.

The role of warm ischemia time on functional outcomes after robotic partial nephrectomy: a radionuclide renal scan study from the clock randomized trial

PURPOSE

To evaluate the relationship between warm ischemia time (WIT) duration and renal function after robot-assisted partial nephrectomy (RAPN).

METHODS

The CLOCK trial is a phase 3 randomized controlled trial comparing on- vs off-clamp RAPN. All patients underwent pre- and postoperative renal scintigraphy. Six-month absolute variation of eGFR (AV-GFR), rate of relative variation in eGFR over 25% (RV-GFR > 25), absolute variation of split renal function (SRF) at scintigraphy (AV-SRF). The relationships WIT/outcomes were assessed by correlation graphs and then modeled by uni- and multivariable regression.

RESULTS

324 patients were included (206 on-clamp, 118 off-clamp RAPN). Correlation graphs showed a threshold on WIT equal to 10 min. The differences in outcome measures between cases with WIT < vs ≥ 10 min were: AV-GFR - 3.7 vs - 7.5 ml/min (p < 0.001); AV-SRF - 1% vs - 3.6% (p < 0.001); RV-GFR > 25 9.3% vs 17.8% (p = 0.008). Multivariable models found that AV-GFR was related to WIT ≥ 10 min (regression coefficient [RC] - 0.52, p = 0.019), age (RC - 0.35, p = 0.001) and baseline eGFR (RC - 0.30, p < 0.001); RV-GFR > 25 to WIT ≥ 10 min (odds ratio [OR] 1.11, p = 0.007) and acute kidney injury defined as > 50% increase in serum creatinine (OR 19.7, p = 0.009); AV-SRF to WIT ≥ 10 min (RC - 0.30, p = 0.018), baseline SRF (RC - 0.76, p < 0.001) and RENAL score (RC - 0.60. p = 0.028). The main limitation was that the CLOCK trial was designed on a different endpoint and therefore the present analysis could be underpowered.

CONCLUSIONS

Up to 10 min WIT had no consequences on functional outcomes. Above the 10-min threshold, a statistically significant, but clinically negligible impact was found.