R.E.N.A.L. Nephrometry Score Predicts Non-neoplastic Parenchymal Volume Removed During Robotic Partial Nephrectomy

Predicting short- and long-term renal function following partial and radical nephrectomy

OBJECTIVES

To externally validate the previously published Mayo clinic model for the prediction of early (<30 days) postoperative renal failure, which relies solely on preoperative estimated glomerular filtration rate (eGFR) and develop a novel model for the prediction of long-term (>30 days) renal function after partial nephrectomy (PN) and radical nephrectomy (RN), including patient factors and nephrometry scores.

PATIENTS AND METHODS

Retrospective, single-center cohort study on patients who underwent PN or RN for a unilateral renal tumor between 2003 and 2019 with a preoperative eGFR of at least 15 ml/min/1.73m². Early postoperative renal failure was defined as eGFR <15 ml/min/1.73 m² or receipt of dialysis within 30 days. We determined the area under the receiver operating characteristics curve (AUC) to assess the Mayo clinic model's discriminative power. We used hierarchical linear mixed models with backward selection of candidate variables to develop a prediction model for long-term eGFR following PN and RN, separately. Their predictive ability was quantified using the marginal and conditional R²_GLMM and an internal validation.

RESULTS

We included 421 patients (7,548 eGFR observations) who underwent PN and 271 patients (6,530 eGFR observations) who underwent RN. The Mayo clinic model for prediction of early postoperative renal failure following PN and RN showed an AUC of 0.816 (95% CI 0.718-0.920) and 0.825 (95% CI 0.688-0.962), respectively. In multivariable models, long-term eGFR following PN was associated with age, diabetes, the presence of a solitary kidney, tumor diameter and preoperative eGFR, while long-term eGFR following RN was associated with age, body mass index, RENAL nephrometry score and preoperative eGFR. Marginal and conditional R²_GLMM were 0.591 and 0.855 for the PN model, and 0.363 and 0.849 for the RN model, respectively.

CONCLUSIONS

The Mayo clinic model for short-term renal failure prediction showed good accuracy on external validation. Our long-term eGFR prediction models depend mostly on host factors as opposed to tumor complexity and can aid in decision-making when considering PN vs. RN.

Comparison of Differential Functional Outcomes After Partial Nephrectomy Between Moderate and High Complex Renal Tumor Evaluated with Diethylenetriamine Pentaacetic Acid Scan: A Propensity Score Matched Analysis

OBJECTIVE

The aim of this study was to compare functional outcomes after partial nephrectomy (PN) between moderate and high complex renal tumors evaluated with a diethylenetriamine pentaacetic acid (DTPA) scan [moderate vs. high: RENAL nephrometry score (RNS) 7-9 vs. 10-12].

METHODS

From January 2004 to December 2019, 471 patients with an RNS of 7-9 (moderate) and 164 patients with an RNS of 10-12 (high) who underwent PN were analyzed for renal function outcomes. The glomerular filtration rate (GFR) was measured using a DTPA scan and calculated the GFR using the Modification of Diet in Renal Disease (MDRD) formula, respectively. Trifecta/pentafecta outcome, recurrence-free survival, and overall survival were compared after propensity score matched analysis (PSMA).

RESULTS

After PSMA, 156 cases in each group were matched without significant difference in the preoperative factor. At the postoperative first year, there was no significant difference in the trifecta (p = 0.320), MDRD-based (p = 0.729), or DTPA-based pentafecta achievement rate (p = 0.964) between groups. At postoperative 5 years, DTPA-based total GFR (93.6% vs. 93.8%) and the operated kidney GFR preservation rate (89.9% vs. 81.7%) did not differ significantly (p > 0.05). Kaplan-Meier survival analysis showed no significant differences in survival outcomes (p > 0.05). Significant predictors of de novo chronic kidney disease (CKD) stage 3 or higher at the postoperative first year were age [hazard ratio (HR) 1.10, 95% confidence interval (CI) 1.03-1.17, p = 0.005] and preoperative DTPA-based total GFR (HR 0.94, 95% CI 0.91-0.98, p = 0.001).

CONCLUSION

High complex tumors can be treated with PN without significant deterioration in renal function. The postoperative function of the operated kidney was preserved by up to 80% in the long term compared with the preoperative period. However, PN should be selectively performed with caution to avoid the occurrence of postoperative CKD.

The Effect of Remote Ischemic Preconditioning on Serum Creatinine in Patients Undergoing Partial Nephrectomy: A Randomized Controlled Trial

Renal function declines after partial nephrectomy due to ischemic reperfusion injury induced by surgical insult or renal artery clamping. The effect of remote ischemic preconditioning (RIPC) on reducing renal injury after partial nephrectomy has not been studied regarding urinary biomarkers. Eighty-one patients undergoing partial nephrectomy were randomly assigned to either RIPC or the control group. RIPC protocol consisted of four cycles of five-min inflation and deflation of a blood pressure cuff to 250 mmHg. Serum creatinine levels were compared at the following time points: preoperative baseline, immediate postoperative, on the first and third days after surgery, and two weeks after surgery. The incidence of acute kidney injury, other surgical complication rates, and urinary biomarkers, including urine creatinine, β-2 microglobulin, microalbumin, and N-acetyl-beta-D-glucosaminidase were compared. Split renal functions measured by renal scan were compared up to 18 months after surgery. There was no significant difference in the serum creatinine level on the first postoperative day (median (interquartile range) 0.87 mg/dL (0.72–1.03) in the RIPC group vs. 0.92 mg/dL (0.71–1.12) in the control group, p = 0.728), nor at any other time point. There was no significant difference in the incidence of acute kidney injury. Secondary outcomes, including urinary biomarkers, were not significantly different between the groups. RIPC showed no significant effect on the postoperative serum creatinine level of the first postoperative day. We could not reveal any significant difference in the urinary biomarkers and clinical outcomes. However, further larger randomized trials are required, because our study was not sufficiently powered for the secondary outcomes.

Endophytic Renal Cell Carcinoma Treated with Robot-Assisted Surgery: Functional Outcomes - A Comprehensive Review of the Current Literature

INTRODUCTION

Robotic surgery for the management of localized renal cell carcinoma (RCC) has gained increasing popularity during the last decade. An endophytic renal tumour represents a surgical technical challenge in terms of identification and resection related to the lack of external visual cues on the kidney surface.

MATERIALS AND METHODS

There is little evidence of functional outcomes of robotic surgery on treating endophytic masses. For this reason, we wanted to review the contemporary literature on the functional outcomes of endophytic RCC treated with robotic surgery.

RESULTS

Many studies investigating robotic partial nephrectomy for totally endophytic RCC confirmed the good functional results of this approach at intermediate follow-up. The greater relative importance of volume loss versus ischaemia duration in predicting long-term renal function after partial nephrectomy is now established, and the robotic technique may facilitate volume preservation. Accurate use of intra-operative ultrasonography, enucleation, and intra-operative techniques using near-infrared fluorescence imaging with indocyanine green dye could minimize excision of the parenchyma and prevent devascularization of adjacent healthy parenchyma.

CONCLUSIONS

Unfortunately, the overall quality of the literature evidence and the high risk of selection bias limit the possibility of any causal interpretation about the relationship between the surgical technique used and functional outcomes.

Predictive Value of Nephrometry Scores in Nephron-sparing Surgery: A Systematic Review and Meta-analysis

CONTEXT

Over the last decade, several nephrometry scores (NSs) have been introduced with the aim of facilitating preoperative decision making, planning, and counseling in the field of nephron-sparing surgery. However, their predictive role remains controversial.

OBJECTIVE

To describe currently available nephrometry scores and to determine their predictive role for different outcomes by performing a systematic review and meta-analysis of the literature.

EVIDENCE ACQUISITION

PubMed, Embase®, and Web of Science were screened to identify eligible studies. Identification and selection of the reports were conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA). A pooled analysis of NS predictive role of intraoperative, postoperative, oncological, and functional outcomes was performed. Odds ratio was considered the effect size. All the analyses were performed using Stata 15.0, and statistical significance was set at p≤ 0.05.

EVIDENCE SYNTHESIS

Overall, 51 studies meeting our inclusion criteria were identified and considered for the analysis. Except for one prospective randomized trial, all the studies were retrospective. All the studies were found to be of intermediate quality, except for one of high quality. Most studies assessed the predictive role of the Radius-Exophytic/Endophytic-Nearness-Anterior/Posterior-Location (RENAL) and Preoperative Aspects and Dimensions Used for an Anatomical (PADUA) scores, mostly regarding complications after nephron-sparing surgery. RENAL was an independent predictor of an on-clamp procedure (p< 0.001). Mayo Adhesive Probability score was related to adhesive perinephric fat (p= 0.005). Continuous and high-complexity RENAL scores were predictors of warm ischemia time (WIT; p= 0.006 and p< 0.001, respectively). Continuous (p< 0.001) and high-complexity (p< 0.001) PADUA scores were related to WIT. Continuous and high-complexity RENAL scores were predictors of overall complications (p= 0.002 and p< 0.001, respectively). PADUA score was related to complications both as continuous (p< 0.001) and as a categorical value (p< 0.002). The RENAL scores R=3 (p= 0.008), E=2 (p= 0.039), and hilar location (p= 0.006) were predictors of histological malignancy. Continuous and categorical RENAL scores were independent predictors of an estimated glomerular filtration rate (eGFR) increase (p= 0.006 and p< 0.001, respectively). The Diameter-Axial-Polar score (p= 0.018) and Peritumoral Artery Scoring System (PASS; p= 0.02) were also independent predictors.

CONCLUSIONS

The literature regarding nephrometry scoring systems is sparse, and mostly focused on RENAL and PADUA, which are easy to calculate and have a good correlation with most outcomes. Renal Pelvic Score is the best predictor of pelvicalyceal entry/repair and urine leak, whereas Surgical Approach Renal Ranking and PASS strongly predict surgical approach and renal function variation, respectively. Other nephrometry scores based on mathematical models are limited by their complexity, and they lack evidence supporting their predictive value.

PATIENT SUMMARY

We reviewed the medical literature regarding the use and value of so-called "nephrometry scores," which are scoring systems based on radiological imaging and made to grade the complexity of a renal tumor. We analyzed whether these scoring systems can predict some of the outcomes of patients undergoing surgical removal of renal tumors.

Predictive factors for the development of renal insufficiency following partial nephrectomy and subsequent renal function recovery: A multicenter retrospective study

Patients who undergo partial nephrectomy (PN) may exhibit renal function insufficiency, and a subset of these patients achieves renal function recovery. We evaluated the predictors of renal insufficiency and subsequent renal function recovery following PN. Data on 393 patients who underwent PN for solid renal tumors between March 2001 and November 2013, obtained from 6 institutions, were retrospectively reviewed. Renal insufficiency was defined as new onset of chronic kidney disease stage ≥3 postoperatively on the second of 2 consecutive tests. Renal function recovery was defined as an estimated glomerular filtration rate ≥60 ml/minute/1.73 m following renal insufficiency. Tumor complexity was stratified according to the RENAL classification system. The median (interquartile range) age, tumor size, and follow-up period were 53 (45-63) years, 2.6 (1.9-3.8) cm, and 36 (12-48) months, respectively. Tumors were of low complexity in 258/393 (65.6%) of cases. Renal insufficiency developed in 54/393 (13.5%) patients, in which age ≥60 years and preoperative creatinine ≥1.1 mg/ml were independent predictors. Tumor complexity, clamp type, and operative method were not significant prognostic factors. Among patients with newly developed renal insufficiency, 18/54 (33.3%) patients exhibited renal function recovery within a median period of 18 months, of which preoperative creatinine <1.1 mg/ml was an independent predictor. Age ≥60 years and preoperative creatinine ≥1.1 mg/ml were risk factors for renal insufficiency following PN. Patients with renal insufficiency whose preoperative creatinine was <1.1 mg/ml were likely to have renal function recovery.

Comparing Off-clamp and On-clamp Robot-assisted Partial Nephrectomy: A Prospective Randomized Trial

OBJECTIVE

To determine whether performing robot-assisted partial nephrectomy without warm ischemia "off-clamp" results in favorable postoperative renal functional outcomes compared with the on-clamp method.

METHODS

We conducted a prospective trial of 80 patients who underwent robot-assisted partial nephrectomy. They were randomized in a 1:1 ratio to undergo the procedure with renal artery clamping or without clamping. The groups were compared across demographics, operative information, perioperative outcomes, and postoperative renal function. We assessed renal function by estimated glomerular filtration rate and renal scintigraphy both preoperatively and at 3 months postoperatively.

RESULTS

Patients in the on-clamp and off-clamp groups were similar in age, gender, body mass index, comorbidities, clinical tumor size, nephrometry score, and laterality. Off-clamp procedures were lengthier at an average 178.0 minutes vs 156.0 minutes for on-clamp (P = .011). Estimated blood loss, rates of pelvicalyceal repair, postoperative complications, and positive margins were not different. At a median 3-month follow-up, no significant differences were seen in change in postoperative estimated glomerular filtration rate or percent split renal function between both groups.

CONCLUSION

In this prospective study, off-clamp robot-assisted partial nephrectomy resulted in similar perioperative outcomes compared with the on-clamp technique. No benefit was demonstrated in the preservation of renal function. Urologists may safely employ either an on-clamp or off-clamp strategy depending on surgeon preference and patient-specific factors including baseline renal insufficiency, multiple masses, or solitary kidney.

Optimization of renal function preservation during robotic partial nephrectomy

Over the past few years, the role of robotic-assisted partial nephrectomy (RPN) has exponentially grown. Multiple recognized factors contribute to postoperative renal function in patients undergoing RPN. The aim of this review is to identify these potential factors, and to evaluate strategies that may help optimize the goal of renal function preservation. A nonsystematic literature review was performed to retrieve the most recent evidence on factors contributing to renal function post-RPN. Analyzed elements include baseline factors (tumor complexity and patient characteristics), intraoperative (surgical) factors (control of the renal hilum and type of ischemia, resection technique, renorrhaphy technique), and pharmacotherapeutics. In conclusion, the advantages of robotic surgery in the setting of partial nephrectomy (PN) are becoming well established. Maximal preservation of renal function remains a priority goal of the procedure, and it is influenced by a plethora of factors. Adequate patient selection using radiomics, control of comorbidities, utilization of evidence-based intraoperative techniques/strategies, and postoperative care are key components of postoperative preservation of renal function. Further investigations regarding these factors and their effects on long-term renal function are necessary and will continue to aid in guiding appropriate patient care.

Change in Nephrometry Scoring in Small Renal Masses (<4 cm) on Active Surveillance: Preliminary Observations From Tayside Active Surveillance Cohort (TASC) Study

RATIONALE AND OBJECTIVES

Prediction of growth, in particular knowing the possibility of aggressive cancer in small renal masses on active surveillance, remains poorly understood. The study was designed to determine whether serial nephrometry score measurements could predict possibility of aggressive malignancy (grade of cancer) in patients with small renal masses opting for active surveillance initially.

MATERIALS AND METHODS

One hundred sixteen patients between January 2000 and December 2016 undergoing partial nephrectomy were recruited. Out of these, 97 were analyzed using different nephrometry scoring systems. Measurement of nephrometry scores (Radius of tumors, Exo/Endophytic; Nearness of tumors to the collecting system or sinus; Anterior/posterior; Location in relation to polar lines, Preoperative Aspects and Dimensions Used for Anatomical, Centrality Index) was performed by two researchers. Among the patients opting for partial nephrectomy, 40 were on active surveillance for at least 12 months (mean 32; 12-60 months) before partial nephrectomy. Computed tomography scan images of these patients were retrieved and analyzed including comparison to histopathology.

RESULTS

Nephrometry scores measured on serial computed tomography scan images showed a significant correlation between change in score and grade of cancer on multivariate analysis (P value .001). Addition of multivariate analysis to nomogram based on change in size alone did not improve predictive value of area under the curve significantly.

CONCLUSIONS

Change in nephrometry scoring measurements correlates with grade of cancer in small renal masses but falls short of significantly predicting presence of malignancy or grade of cancer on nomogram in patients opting for active surveillance for small renal masses. At present, this approach may be inadequate for decision-making.

Robot-assisted partial nephrectomy: How to minimise renal ischaemia

Renal ischaemia research has shown an increase in renal damage proportional to ischaemic time. Therefore, we assessed the importance of renal ischaemic times for warm and cold ischaemia approaches, and explored the different surgical techniques that can help to minimise renal ischaemia in robot-assisted partial nephrectomy (RAPN). Minimising renal ischaemia during nephron-sparing surgery (NSS) is a key factor in preserving postoperative renal function. Current data support a safe warm ischaemia time (WIT) of ≤25 min and cold ischaemic time of ≤35 min, resulting in no significant deterioration in renal function. In general, patients undergoing NSS have increased comorbidities, including chronic kidney disease, and in these patients it is difficult to predict their postoperative renal function recovery. With RAPN, efforts should be made to keep the WIT to <25 min, as minimising the ischaemic time is vital for preservation of overall renal function and remains a modifiable risk factor. Parenchymal or segmental artery clamping, early unclamping or off-clamp techniques can be adopted when ischaemic times are likely to be >25 min, but may not lead to superior functional outcome. Careful preoperative planning, tumour factors, and meticulous surgical technique are critical for optimum patient outcome.

Predictors of new-onset chronic kidney disease in patients managed surgically for T1a renal cell carcinoma: An Australian population-based analysis

BACKGROUND

New-onset chronic kidney disease (CKD) following surgical management of kidney tumors is common. This study evaluated risk factors for new-onset CKD after nephrectomy for T1a renal cell carcinoma (RCC) in an Australian population-based cohort.

METHODS

There were 551 RCC patients from the Australian states of Queensland and Victoria included in this study. The primary outcome was new-onset CKD (eGFR <60 mL/min per 1.73 m² ) and the secondary outcome was new-onset moderate-severe CKD (<45 mL/min per 1.73 m² ). Multivariable logistic regression was used to evaluate associations between patient, tumor and health-service characteristics and these outcomes.

RESULTS

Forty percent (219/551) of patients developed new-onset CKD, and 12% (68/551) experienced new-onset moderate-severe CKD. Risk factors for new-onset CKD were age, lower preoperative eGFR, tumor size >20 mm, radical nephrectomy, lower hospital caseloads (<20 cases/year), and rural place of residence. The associations between rural place of residence and low center volume were a consequence of higher radical nephrectomy rates.

CONCLUSION

Risk factors for CKD after nephrectomy generally relate to worse baseline health, or likelihood of undergoing radical nephrectomy. Surgeons in rural centres and hospitals with low caseloads may benefit from formalized integration with specialist centers for continued professional development and case-conferencing, to assist in management decisions.