Prognostic significance of preoperative kidney volume for predicting renal function in renal cell carcinoma patients receiving a radical or partial nephrectomy

Age and Pre-operative HbA1c levels affect renal function compensation in living kidney donors

OBJECTIVES

About 90% of Japanese kidney transplantations are conducted from living donors, and their safety and the maintenance of their renal function are critical. This study aims to identify factors that affect the compensation of renal function in living kidney donors after donor nephrectomy.

METHOD

In a retrospective cohort study, we reviewed data from 120 patients who underwent nephrectomy as living kidney transplant donors in our department from 2012 to 2021. Univariable and multivariable linear regression analyses were performed for donor factors affecting renal function after donor nephrectomy.

RESULT

The multivariable linear regression model revealed that the donor's age (p = 0.025), preoperative estimated Glomerular Filtration Rate (eGFR) (p < 0.001), and hemoglobin A1c (HbA1c) (p = 0.043) were independent risk factors for eGFR at six months after nephrectomy. The eGFR deterioration was more strongly associated with age in females than in males, whereas higher HbA1c values were more strongly associated with eGFR deterioration in males. Higher donor age and higher HbA1c each enhance the deterioration of eGFR six months after living donor nephrectomy. The data suggest that old age in especially female donors and preoperative higher HbA1c in male donors have a harmful impact on their renal function compensation.

Longitudinal changes in renal parenchymal volume and function status after partial nephrectomy: a retrospective cohort study

BACKGROUND

The ipsilateral renal parenchymal volume (RPV) experiences a sharp decrease shortly after partial nephrectomy (PN), mainly due to surgical remove or devascularization of kidney tissue. However, the subsequent change of RPV and its association with glomerular filtration rate (GFR) fast decline remains unknown. Our objective was to investigate the change of ipsilateral RPV and renal function status from new baseline (1-12 months after PN) to latest follow-up (≥1 year) after PN, and to explore factors associated with ipsilateral RPV decrease rate and correlation between RPV decrease and GFR fast decline.

MATERIALS AND METHODS

A retrospective review of 367 patients with PN was conducted. Three-dimensional reconstruction of computed tomography (CT)/MRI images was performed for RPV calculation. Spectrum score was used to assess the degree of acute kidney injury (AKI) in the operated kidney after PN. GFR decline greater than 3 ml/min/1.73 m 2 /year was defined as GFR fast decline. One hundred fourteen patients underwent abdominal surgery was used as control. Predictive factors for subsequent decrease of RPV rate and GFR fast decline were evaluated by linear and logistic regression, respectively.

RESULTS

With a median interval time of 21.1 (interquartile range:13.8-35.5) months, median ipsilateral RPV significantly decreased from 118.7 (interquartile range:100.7-137.1) ml at new baseline to 111.8 (IQR: 92.3-131.3) ml at latest follow-up. The interval time [β: 1.36(0.71-2.01), P <0.001] and spectrum score [β: 5.83 (2.92-8.74), P <0.001] were identified as independent predictors of ipsilateral RPV decrease rate. GFR fast decline was observed in 101 (27.5%) patients. Annual ipsilateral RPV decrease rate [odds ratio:1.67 (1.05-2.67), P =0.03] and overweight [odds ratio:1.63 (1.02-2.60), P =0.04] were independent predictors of GFR fast decline.

CONCLUSIONS

Ipsilateral RPV experienced a moderate but significant decrease during follow-up after PN, especially in those with severer acute kidney injury. The presence of GFR fast decline was found to be associated with reduction of ipsilateral RPV, particularly in overweight individuals.

Real-time estimation of nephron activity with a linear measurement system (RENAL-MS) predicts postoperative estimated glomerular filtration rate

OBJECTIVE

To determine whether a simple point-of-care measurement system estimating renal parenchymal volume using tools ubiquitously available could be used to replace nuclear medicine renal scintigraphy (NMRS) in current clinical practice to predict estimated glomerular filtration rate (eGFR) after nephrectomy by estimating preoperative split renal function.

PATIENTS AND METHODS

We performed a retrospective review of patients who underwent abdominal cross-sectional imaging (computed tomography/magnetic resonance imaging) and mercaptoacetyltriglycine (MAG3) NMRS prior to total nephrectomy at a single institution. We developed the real-time estimation of nephron activity with a linear measurement system (RENAL-MS) method of estimating postoperative renal function via the following technique: renal parenchymal volume of the removed kidney relative to the remaining kidney was estimated as the product of renal length and the average of six renal parenchymal thickness measurements. The utility of this value was compared to the utility of the split renal function measured by MAG3 for prediction of eGFR and new onset Stage 3 chronic kidney disease (CKD) at ≥90 days after nephrectomy using uni- and multivariate linear and logistic regression.

RESULTS

A total of 57 patients met the study criteria. The median (interquartile range [IQR]) age was 69 (61-80) years. The median (IQR) pre- and postoperative eGFR was 74 (IQR 58-90) and 46 (35-62) mL/min/1.73 m2 , respectively. [Correction added on 29 December 2023, after first online publication: The data numbers in the preceding sentence have been corrected.] Correlations between actual and predicted postoperative eGFR were similar whether the RENAL-MS or NMRS methods were used, with correlation using RENAL-MS being slightly numerically but not statistically superior (R = 0.82 and 0.76; P = 0.138). Receiver operating characteristic curve analysis using logistic regression estimates incorporating age, sex, and preoperative creatinine to predict postoperative Stage 3 CKD were similar between RENAL-MS and NMRS (area under the curve 0.93 vs. 0.97). [Correction added on 29 December 2023, after first online publication: The data numbers in the preceding sentence have been corrected.] CONCLUSION: A point-of-care tool to estimate renal parenchymal volume (RENAL-MS) performed equally as well as NMRS to predict postoperative eGFR and de novo Stage 3 CKD after nephrectomy in our population, suggesting NMRS may not be necessary in this setting.

Choosing the larger kidney on CT volumetry: a study on the early post-donation kidney function of living donors

BACKGROUND

Selecting the smaller kidney for donation has been advocated if there is a size difference of > 10% between the 2 kidneys but has never been prospectively evaluated. With increase in donor nephrectomies, it is important to evaluate this to minimize loss of renal function to donors.

METHODS

75 consecutive donor nephrectomy patients were included in our longitudinal study. The Split Renal Volume (SRV) of bilateral kidneys were measured using contrasted computer tomography scans and patients segregated into 2 groups depending on donated kidney having more (Group 1) or less than (Group 2) 52.5% of SRV.

RESULTS

Patients in Group 1 (n = 19) and 2 (n = 56) were of similar age (43.8 vs. 48.3), BMI (22.4 vs. 25.2), sex (57.9 vs. 55.4% women), respectively. Although total kidney volumes were similar in both groups, Group 1 had significantly smaller right kidney volumes (120.4 ± 24.9 vs. 142.7 ± 28.4 mls, p = 0.003). EGFR pre-operatively (116.3 ± 20.8 vs. 106.3 ± 23.8 mL/min/1.73 m2) and at 6-months (65.7 ± 13.3 vs. 66.9 ± 15.5 mL/min/1.73 m2) were not different between groups. However, patients in Group 1 had significantly greater absolute (50.6 ± 14.9 vs. 39.5 ± 14.7 mL/min/1.73 m2) and relative decline (43.0 ± 8.6 vs. 36.3 ± 10.6%) in eGFR at 6 months (p = 0.06, 0.009).

CONCLUSION

With a SRV difference of 5% between the 2 sides, removal of the larger kidney for living kidney donation resulted in greater early decline of renal function than kidney donors whose larger or equivalent kidney is preserved.

Volumetric and functional outcomes at 1-year between percutaneous-ablation and partial-nephrectomy for T1b renal tumors

INTRODUCTION

Indication for percutaneous-ablation (PA) is gradually expanding to renal tumors T1b (4-7cm). Few data exist on the alteration of renal functional volume (RFV) post-PA. Yet, it is a surrogate marker of post partial-nephrectomy (PN) glomerular filtration rate (GFR) impairment. The objective was to compare RFV and GFR at 1-year post-PN or PA, in this T1b population.

METHODS

Patients with unifocal renal tumor≥4cm treated between 2014 and 2019 were included. Tumor, homolateral (RFVh), contralateral RFV, and total volumes were assessed by manual segmentation (3D Slicer) before and at 1 year of treatment, as was GFR. The loss of RFV, contralateral hypertrophy, and preservation of GFR were compared between both groups (PN vs. PA).

RESULTS

144 patients were included (87PN, 57PA). Preoperatively, PA group was older (74 vs. 59 years; P<0.0001), had more impaired GFR (73 vs. 85mL/min; P=0.0026) and smaller tumor volume(31.1 vs. 55.9cm3; P=0.0007) compared to PN group. At 1 year, the PN group had significantly more homolateral RFV loss (-19 vs. -14%; P=0.002), and contralateral compensatory hypertrophy (+4% vs. +1,8%; P=0.02, respectively). Total-RFV loss was similar between both (-21.7 vs. -19cm3; P=0.07). GFR preservation was better in the PN group (95.9 vs. 90.7%; P=0.03). In multivariate analysis, age and tumor size were associated with loss of RFVh.

CONCLUSION

For renal tumors T1b, PN is associated with superior compensatory hypertrophy compared with PA, compensating for the higher RFVh loss, resulting in similar ΔRFV-total between both groups. The superior post-PN GFR preservation suggests that the preserved quantitative RFV factor is insufficient. Therefore, the underlying quality of the parenchyma would play a major role in postoperative GFR.

Stability of renal parenchymal volume and function during active surveillance of renal oncocytoma patients

INTRODUCTION AND OBJECTIVE

To evaluate whether significant loss in ipsilateral renal parenchymal volume (IRPV) and renal function occurs during active surveillance (AS) of renal oncocytoma (RO) patients.

METHODS

Renal function (estimated glomerular filtration rate, eGFR) dynamics were retrospectively analyzed in 32 consecutive biopsy-diagnosed RO patients managed with AS at a National Comprehensive Cancer Network institute. Three-dimensional kidney and tumor reconstructions were generated and IRPV was calculated using volumetry software (Myrian®) for all patients with manually estimated RO growth >+10 cm3. GFR and IRPV were compared at AS initiation vs. the last follow-up using 2-sided paired t-tests. The correlation between change in IRPV and change in RO size or GFR was tested using a Spearman coefficient.

RESULTS

With median follow-up of 37 months, there was no significant change between initial vs. last eGFR (median 71.0 vs. 70.5 ml/min/1.73 m2, P = 0.50; median change -3.0 ml/min/1.73 m2). Among patients (n = 17) with RO growth >+10 cm3 during AS (median growth +28.6 cm3, IQR +16.9- + 46.5 cm3), IRPV generally remained stable (median change +0.5%, IQR -1.2%- + 1.2%), with only 2 cases surpassing 5% loss. No IRPV loss was detected among any patient within the top tertile of RO growth magnitude. RO growth magnitude did not correlate with loss of either IRPV (ρ = -0.30, P = 0.24) or eGFR (ρ = -0.16, P = 0.40), including among patient subsets with lower initial eGFR. Study limitations include a lack of long-term follow-up.

CONCLUSIONS

Volumetry is a promising novel tool to measure kidney and tumor tissue changes during AS. Our study using volumetry indicates that clinically significant loss of IRPV or eGFR is uncommon and unrelated to tumor growth among untreated RO patients with intermediate follow-up. These findings support that AS is in general functionally safe for RO patients, however longer study is needed to determine safety durability, particularly among uncommon ≥cT2 RO variants.

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

OBJECTIVE

To provide a narrative review of the major advances regarding ischaemia and functional recovery after partial nephrectomy (PN), along with the ongoing controversies.

METHODS

Key articles reflecting major advances regarding ischaemia and functional recovery after PN were identified. Special emphasis was placed on contributions that changed perspectives about surgical management. Priority was also placed on randomized trials of off-clamp vs on-clamp cohorts.

RESULTS

A decade ago, 'Every minute counts' was published, showing strong correlations between duration of ischaemia and development of acute kidney injury (AKI) and chronic kidney disease after clamped PN. This reinforced perspectives that ischaemia was the main modifiable factor that could be addressed to improve functional outcomes and helped spur efforts towards reduced or zero ischaemia PN. These approaches were associated with strong functional recovery and some peri-operative risk, although they were generally safe in experienced hands. Further research demonstrated that, when parenchymal volume changes were incorporated into the analyses, ischaemia lost statistical significance, and percent parenchymal volume saved proved to be the main determinant. Cold ischaemia was confirmed to be highly protective, and limited warm ischaemia also proved to be safe. The reconstructive phase of PN, with avoidance of parenchymal devascularization, appears to be most important for functional outcomes. Randomized trials of on-clamp vs off-clamp PN have shown minimal impact of ischaemia on functional recovery.

CONCLUSIONS

The past decade has witnessed great progress regarding functional recovery after PN, with many lessons learned. However, there are still unanswered questions, including: What is the threshold of warm ischaemia at which irreversible ischaemic injury begins to develop? Are some cohorts at increased risk for AKI or irreversible ischaemic injury? and Which patients should be prioritized for zero-ischaemia PN?

Identification of predictive factors for outcomes after robot-assisted partial nephrectomy based on three-dimensional reconstruction of preoperative enhanced computerized tomography

Background

Information from the RENAL score is limited. This study aimed to identify new parameters based on three-dimensional (3D) reconstruction of preoperative enhanced computerized tomography (CT) for predicting outcomes after robot-assisted partial nephrectomy (RPN).

Materials and methods

The records of kidney cancer patients who underwent RPN at Tongji Hospital from March 2015 to July 2019 were reviewed. Demographic data, laboratory examinations, postoperative hospitalization time, and enhanced CT were retrospectively collected. Some tumor parameters were obtained from 3D reconstruction of CT data. The association between these predictive factors and outcomes after RPN was analyzed.

Results

A larger tumor bed area (TBA) was associated with a longer warm ischemia time (WIT) (P-value <0.001) and tumor resection time (P-value <0.001). Moreover, TBA was significantly associated with the elevation of postoperative creatinine (P-value = 0.005). TBA (P = 0.008), distance from the tumor to the first bifurcation of the renal artery (DTA) (P <0.034), and RENAL score (P = 0.005) were significantly associated with WIT in univariate logistic regression. In multivariate logistic regression, TBA (P = 0.026) and DTA (P = 0.048) were independent risk factors for prolonged WIT (over 25 min). The predictive effect of the combination of TBA, DTA, and RENAL score was higher than the predictive effect of RENAL score alone for WIT (area under curve: 0.786 versus 0.72).

Conclusion

TBA and DTA are independently associated with the WIT of RPN, which provides additional assessment value for the complexity of kidney cancer in RPN over the RENAL score.

Preoperative versus Postoperative Compensation of the Contralateral Normal Kidney in Patients Treated with Radical Nephrectomy for Renal Cell Carcinoma

Background: We sought to identify the factors affecting renal compensatory processes that occur preoperatively as well as postoperatively in patients treated with radical nephrectomy (RNx) for renal cell carcinoma (RCC). Methods: We retrospectively reviewed the records of 906 patients treated with RNx for RCC. We defined the early compensatory process (process 1) as compensatory adaptation of the contralateral normal kidney (CNK) before RNx. We defined the late compensatory process (process 2) as compensatory adaptation of the CNK after RNx. Total compensation was defined as the combination of these two processes. Multivariable logistic regression analyses were used to identify significant factors associated with processes 1, 2 and total compensation. Results: Mean preoperative, 1-week, and 5-year postoperative estimated glomerular filtration rates (eGFR) were 84.5, 57.6 and 63.7 mL/min/1.73 m², respectively. Female sex (p < 0.001), lower body mass index (BMI) (p < 0.001), absence of hypertension (p = 0.019), lower preoperative eGFR (p < 0.001), larger tumor volume (p < 0.001), and larger CNK volume (p < 0.001) were significantly associated with process 1. Younger age (p = 0.019), higher BMI (p < 0.001), and absence of diabetes mellitus (DM) (p = 0.033) were significantly associated with process 2. Female sex (p < 0.001), younger age (p < 0.001), absence of DM (p = 0.002), lower preoperative eGFR (p < 0.001), and larger tumor (p = 0.001) and CNK volumes (p < 0.001) were significantly associated with total compensation. Conclusions: Different factors affected each compensatory process. Process 1 made a greater contribution to the entire renal compensatory process than process 2.

Can Aortic and Renal Arteries Calcium Scores Be New Factors to Predict Post-Operative Renal Function After Nephron Sparing Surgery?

INTRODUCTION

This study aims to investigate whether the calcification of renal arteries and aorta may be risk factors for developing chronic kidney disease (CKD) after Nephron sparing surgery (NSS).

MATERIALS AND METHODS

The patients that underwent either open or laparoscopic NSS from 2000 to 2019 in 4 different centers were retrospectively assessed. Of these patients, 328 had a non-contrast-enhanced computer tomography. Calcium scores of the renal arteries and abdominal aorta were measured in the non-contrast-enhanced images with the calcium score plugin (version 2.0) of Horos™. Univariate and multivariate logistic regression analysis was performed to determine significant risk factors for developing CKD at the last check-up. Roc curve analysis was performed to determine the optimal cut-off values of age and abdominal aorta calcium scores.

RESULTS

A total of 302 patients, of which 52 (16,6%) with CKD and 252 (83,4%) without CKD at the last check-up, were included in the analysis. The mean warm ischemia duration was significantly higher in patients with CKD (18,79±6,72 vs 16,38±5,57 minutes, p=0,016). The mean size of the tumor diameter and the number of the patients with ≥stage T1b were higher in the group with CKD (p=0,024 and 0,005, respectively). The median calcium scores of the aorta and renal arteries were higher in the group with CKD (p<0,001 and p<0,001, respectively). In multivariate analysis, age >60 years (OR:3,65, p=0,022), calcium score of the aorta (OR:4,07, p=0,029), tumor diameter (OR:1,03, p=0,026) and pre-operative CKD stage (OR:10,13, p<0,001) found the be significant factors for predicting last check-up CKD.

CONCLUSION

The calcium score of the aorta may be used as an additional risk factor to predict post-operative CKD risk after NSS with sensitivity over 80%.

Long-term chronological changes in renal function and functional renal volume after nephron-sparing surgery: A prospective observational study

OBJECTIVES

To investigate long-term chronological changes in functional renal volume and renal function after nephron-sparing surgery, and factors that contribute to the progression of postoperative chronic kidney disease.

METHODS

A total of 80 patients who underwent nephron-sparing surgery were enrolled in this prospective observational study. The renal function deterioration group was defined as patients whose estimated glomerular filtration rate at 5 postoperative years decreased by ≥20% relative to that before surgery.

RESULTS

The predicted estimated glomerular filtration rate, calculated based on the functional renal volume at 5 postoperative years, was strongly correlated with the postoperative estimated glomerular filtration rate (Spearman's ρ = 0.89, P < 0.001). The rate of new-onset stage IIIb chronic kidney disease was significantly higher in the renal function deterioration group than in the stable renal function group (P < 0.001). Multivariate analysis identified proteinuria (P = 0.017), small preoperative total functional renal volume (≤250 mL, P = 0.046) and large tumor volume (≥4.5 mL, P = 0.036) as independent factors associated with renal function deterioration.

CONCLUSIONS

Our findings show that the functional renal volume is significantly associated with renal function, even in the long-term postoperative period. Additionally, for patients with preoperative proteinuria, large tumor volume and small total preoperative functional renal volume, both oncological follow ups and medical interventions, including prevention of lifestyle-related diseases, might prevent the progression of chronic kidney disease.

Comparison of Risk Factors for the Development of Proteinuria After Radical Nephrectomy for Renal Cell Carcinoma

Purpose

We investigated compensatory structural hypertrophy and functional hyperfiltration in patients with renal cell carcinoma (RCC) after radical nephrectomy (RN) according to the presence of proteinuria.

Patients and Methods

We retrospectively enrolled 471 patients who underwent RN for RCC between October 2005 and December 2013. These patients were divided into two groups according to the presence of postoperative proteinuria (trace or greater (≥1+) urine dipstick). We obtained computed tomography images before and 1 year after surgery to calculate the functional renal volume (FRV). The preoperative and postoperative Chronic Kidney Disease Epidemiology Collaboration equation-calculated glomerular filtration rates (CKD-EPI GFRs) per unit FRV (GFR/FRV) were used to calculate the degree of hyperfiltration.

Results

The mean patient age was 54.7±11.1 years, and the mean preoperative CKD-EPI GFR, FRV, and GFR/FRV were 89.3±13.3 mL/min/1.73 m², 357.2±71.8 cm³, and 0.26±0.05 mL/min/1.73 m²/cm³, respectively. The percentage reduction rate of the GFR was not significantly different according to the presence of proteinuria (normal: −28.5±11.6% vs proteinuria: −28.7±15%; p=0.902); however, the postoperative hypertrophic FRV in the remnant kidney was significantly different (normal: 17.5±9.1% vs proteinuria: 13.8±14.1%; p=0.001). Meanwhile, the change in the percentage rate of the GFR/FRV was not significantly different (normal: 21.1±23% vs proteinuria: 23.8±28.3%; p=0.324). Multivariate logistic regression analysis revealed that age (p=0.010) and the GFR/FRV (p<0.001) were significant predictors of postoperative proteinuria.

Conclusion

Compensatory structural hypertrophy and functional hyperfiltration are positive adaptations that reduce the occurrence of proteinuria.

Cause-Specific Mortality Among Survivors From T1N0M0 Renal Cell Carcinoma: A Registry-Based Cohort Study

Objective

More T1N0M0 renal cell carcinoma (RCC) is detected and the prognosis has improved, but, the current focus on non-RCC-related mortality is superficial. We investigated cause-specific mortality and its temporal patterns after an RCC diagnosis.

Methods

In the Surveillance, Epidemiology, and End Results-18 database, patients with T1N0M0 RCC treated with partial nephrectomy (PN) or radical nephrectomy (RN) during 2000-15 were identified. Standardized mortality ratios (SMRs) for cause of death were calculated. Risk predictors for each cause-specific mortality were investigated using the Fine and Gray sub-distribution model.

Results

In all, 68,612 eligible patients were pooled. A total of 14,047 (20.5%) patients had died (cardiovascular disease [CVD], 28.3%; other non-cancer-related diseases, 20.3%; RCC, 18.7%; other cancer types, 16.3%; non-disease events, 16.1%) during follow-up. Heart disease, diabetes mellitus, and cerebrovascular disease were the primary causes of non-RCC-related mortality within 1 year after the diagnosis. The greatest proportion of death (39.0%) occurred within 1-5 years after the diagnosis, mostly due to RCC itself, followed by heart disease. However, >5 years after the diagnosis, heart disease became the leading cause of death. Compared with the general US population, a 21% (SMR, 1.21; 95%CI 1.19-1.23) increased risk of all-mortality was observed; RCC patients had a higher risk of heart disease-related death within 5-10 years (SMR, 1.10; 95%CI 1.04-1.17) and >10 years (1.12; 1.02-1.22) after the diagnosis. Older age and RN increased the death risk of CVD and RCC-specific mortality. Although a larger tumor diameter increased the risk of RCC-specific death, this was not a significant predictor for CVD. Moreover, for T1N0M0 RCC tumors of diameter >4 cm, there was no significant difference in CVD incidence for RN vs. PN.

Conclusions

RCC-specific mortality is a common challenge for the prognosis. Importantly, a large proportion and higher SMRs of other non-RCC-related diseases (especially CVD) should not be disregarded for the better holistic management of survivors of local RCC. Targeted prevention strategies for non-RCC-related death could lead to significant reductions in mortality for RCC survivors.

The importance of kidney volume as a marker in the assessment of living-donor kidney transplantation in Japan

BACKGROUND

In living kidney transplantation, predicting the risk of end-stage kidney disease in the organ donors though crucial remains to be resolved. Thus, any useful biomarker to predict kidney outcome would be highly desirable to safeguard donors.

METHODS

This retrospective study was conducted at Nagoya Daini Red Cross Hospital to confirm whether an increase in preserved kidney volume (PKV) was a predict marker of proteinuria. A change of PKV before and 1 year after kidney donation was measured, and its association with proteinuria 3 years after the donation was analyzed.

RESULTS

A total of 119 kidney donors who met the Japanese donor guideline were enrolled. The mean age was 57.4 years, 46.2% were male. The mean values of the variables before kidney donation (baseline) were: BMI levels: 23.4 kg/m², BSA-adjusted PKV: 132.9 cm³/1.73 m², and estimated glomerular filtration rate (eGFRave): 82.9 mL/min/1.73 m². A positive correlation was noted between BSA-adjusted PKV and eGFRave (r = 0.61, p < 0.001). BSA-adjusted PKV increased by 19.5% 1 year after donation, and the median urine protein was 0.04 g/gCre. Linear regression analyses showed that change of PKV and BSA-adjusted PKV before the donation were significantly associated with proteinuria 3 years after donation.

CONCLUSION

Change of PKV and BSA-adjusted PKV before donation is important factors for proteinuria after donation under the Japanese donor guidelines. Further studies are needed to confirm whether these factors are associated with renal survival after donation.

Renal function after partial nephrectomy following intra-arterial embolization of renal tumors

Laparoscopic Partial Nephrectomy (LPN) after intra-arterial Embolization of renal tumors (LPNE) in a hybrid operating room allows renal tumor enucleation without dissection and clamping of the renal pedicle. The purpose was to assess the potential negative impact of embolization on the renal function. This prospective monocentric study included all patients treated with LPNE between May 2015 and June 2019. Clinical data was collected and incorporated into the UroCCR database (NCT03293563). Glomerular Filtration Rate (GFR) and Computed Tomography Renal Volume (CTRV) were compared before and after 6 months following LPNE. The mean post-operative GFR was 86.6 mL/min (SD 22.9). The mean GFR loss was 9.4% (SD 15.1) and the median renal parenchyma loss was 21 mL (SD 20.6). Using a threshold of 25% GFR loss, age was the only significant predictive factor of renal function impairment according to bivariate (59.5 vs 69.3 years, p = 0.017) and multivariable analysis (OR 1.075, CI 1–1.2], p = 0.05). Significant renal function impairment was not correlated with the renal parenchymal volume loss (OR 0.987, CI [0.95–1.02], p = 0.435). Renal function impairment after LPNE seems to be comparable to other techniques of partial nephrectomy.

Omitting Cortical Renorrhaphy in Robot-Assisted Partial Nephrectomy: Is it Safe? A Single Center Large Case Series

Introduction: Preserving renal function after robot-assisted partial nephrectomy (RAPN) is important and influenced by the technique of renal reconstruction among other parameters, including ischemia time and amount of healthy renal tissue resected. It is believed that reconstruction with a second layer of cortical renorrhaphy is necessary to prevent urinary leaks and postoperative bleeding, but this is associated with the potential loss of healthy renal parenchyma and may result in worse outcomes postoperatively. Purpose: To assess the safety of omitting cortical renorrhaphy during RAPN. Patients and Methods: A retrospective analysis of 146 consecutive patients undergoing a RAPN with single or double layer renorrhaphy at the Wirral University Teaching Hospital from 2014 to 2019. Data obtained included: Patient demographics, tumor RENAL nephrometry, Perioperative parameters; blood loss, duration, and warm ischemia time (WIT), Postop complications, change in estimated glomerular filtration rate (eGFR) (pre and 3 months postop), length of stay, and oncologic outcomes. Results: In total 146 patients were identified. One hundred-six had double renorrhaphy and 40 inner layer only renorrhaphy. No significant differences were seen between these two cohorts in terms of patient demographics, RENAL nephrometry score, tumor size, or location. Perioperative parameters showed a reduced duration of surgery in the single renorrhaphy group with a mean of 125 minutes compared to143 minutes in the double renorrhaphy (p = 0.006) and a tendency toward a shorter WIT of 12.9 minutes vs 14.0 minutes reaching borderline statistical significance (p = 0.05) but no difference in blood loss volume (p = 0.25). Postoperatively there was no statistical difference in the length of hospital stay (p = 0.85), loss in eGFR at 3 months (0.06), or complication (p = 0.56). After a median follow-up of 35 months no recurrences or deaths were observed in either group. Conclusions: Omission of cortical renorrhaphy appears feasible and safe with no urine leaks or excess complications observed.

Role of preoperative MR volumetry in patients with renal cell carcinoma for prediction of postoperative renal function after radical nephrectomy and nephron sparing surgery

Purpose

Preoperative computed tomography or magnetic resonance (MR) imaging are commonly used for radiological evaluation of renal cell carcinoma (RCC) before radical nephrectomy or nephron sparing surgery(NSS). This study aimed to assess the role of MRI for predicting postoperative renal function by preoperative estimation of renal parenchymal volume and correlation with glomerular filtration rate (GFR).

Materials and Methods

A prospective observational study was conducted from February 2015 to October 2016 at a tertiary care hospital in northern India. MR imaging was done on 3 Tesla MR scanner (Signa Hdxt General Electrics, Milwaukee, USA). MR volumetry was used to estimate the renal parenchymal volume. GFR was measured in all patients using Tc99m Diethyl-triamine-penta-acetic acid using Russell’s algorithm. Such measurement was done preoperatively, and postoperatively 3 months after surgery.

Results

30 patients with suspected RCC underwent NSS (n=10) and radical nephrectomy (n=20). Median tumour volume was 175.7cc (range: 4.8 to 631.8cc). The median volume of the residual parenchyma on the affected side was 84.25±41.97cc while that on the unaffected side was 112.25±26.35cc. There was good correlation among the unaffected kidney volume and postoperative GFR for the radical nephrectomy group (r=0.83) as well as unaffected kidney volume, total residual kidney volume and residual volume of affected kidney with postoperative GFR for the NSS group (r=0.71, r=0.73, r=0.79 respectively; P <0.05).

Conclusion

Preoperative residual parenchymal volume on MR renal volumetry correlates well with postoperative GFR in patients with RCC undergoing radical nephrectomy or NSS.

Renorrhaphy techniques and effect on renal function with robotic partial nephrectomy

PURPOSE

The role of robotic partial nephrectomy (RPN) is becoming increasingly prevalent in managing small renal masses. Renal functional outcomes have been reported with relation to the amount of healthy renal parenchyma resected and ischemia time; however, there is limited data on the effect of renorrhaphy on long-term renal function. Our aim is to evaluate the impact of renorrhaphy technique on renal functional outcomes.

METHODS

A nonsystematic literature review was performed to retrieve articles assessing renorrhaphy techniques and renal function outcomes, specifically focusing on single-layer vs. traditional two-layer renorrhaphy.

RESULTS

Performing single-layer renorrhaphy while omitting cortical renorrhaphy appears to improve renal function postoperatively, based on very limited studies in the literature that were evaluated.

CONCLUSION

Single-layer renorrhaphy may be associated with improved postoperative renal function and could prove to be useful in patients with chronic renal insufficiency or solitary kidney. The ongoing clinical trial NCT02131376 may provide further information on the impact of renorrhaphy technique on long-term renal function.

Compensatory renal hypertrophy following nephrectomy: When and how?

Following surgical removal of one kidney, the other enlarges and increases its function. The mechanism for the sensing of this change and the growth is incompletely understood but begins within days and compensatory renal hypertrophy (CRH) is the dominant contributor to the growth. In many individuals undergoing nephrectomy for cancer or kidney donation this produces a substantial and helpful increase in renal function. Two main mechanisms have been proposed, one in which increased activity by the remaining kidney leads to hypertrophy, the second in which there is release of a kidney specific factor in response to a unilateral nephrectomy that initiates CRH. Whilst multiple growth factors and pathways such as the mTORC pathway have been implicated in experimental studies, their roles and the precise mechanism of CRH are not defined. Unrestrained hypoxia inducible factor activation in renal cancer promotes growth and may play an important role in driving CRH.

Organ-sparing procedures in GU cancer: part 1-organ-sparing procedures in renal and adrenal tumors: a systematic review

PURPOSE

Organ-sparing surgery (OSS) for the kidney and adrenals has emerged as the need for preservation of function is paramount in patients with poor functional reserve. As reports increasingly showed that oncological outcomes were equivalent to radical excision, elective OSS became a viable alternative in patients with otherwise normal reserve. In this review, we summarize the current knowledge of OSS for adrenal and renal tumors.

MATERIALS AND METHODS

PubMed, Web of Science and Cochrane Library Central Search were searched for recently published articles up to December 2017. The following keywords were used; "partial adrenalectomy", "adrenal sparing", "partial nephrectomy", "nephron sparing", "kidney/renal cancer".

RESULTS

Partial adrenalectomy became an attractive alternative to total adrenalectomy avoiding adrenal insufficiency. Both minimally invasive surgery and ablative techniques were increasingly reported for adrenal OSS with adequate residual adrenal function and excellent oncological outcome. Radical nephrectomy remained for many years as the gold standard of treatment for organ-confined renal cell carcinoma. As the need to reduce the impact on renal function, more conservative approaches were utilized. Soon, the non-inferiority of nephron-sparing surgery to that of radical excision became evident and elective partial nephrectomy was gaining ground as the standard of care for small renal masses in patients with normal contralateral kidneys.

CONCLUSIONS

Herein, we present a comprehensive review of the current status of OSS in renal and adrenal tumors.

The 3-D Volumetric Measurement Including Resected Specimen for Predicting Renal Function AfterRobot-assisted Partial Nephrectomy

OBJECTIVE

To investigate the relationship between postoperative renal function and resected cortex margin volume calculated by a 3-dimensional reconstruction technique based on the resected specimen, and to determine predictors of renal function after robot-assisted partial nephrectomy.

METHODS

A total of 114 patients underwent robot-assisted partial nephrectomy from 2014 to 2018. Patients without a 1 mm slice computed tomography or renal scintigraphy were excluded. We identified the margins of the tumor from each resected specimen with 2 mm margin being added as the ischemic margin. The volume of the renal cortex was calculated automatically using 3-dimensional volume analyzer software. The total margin volume was excluded from the ipsilateral cortex volume to calculate the cortex volume split. Predicted estimated glomerular filtration rate (eGFR) was calculated using the change in cortex volume and then compared with the actual eGFR.

RESULTS

Eighty-two patients were included in this retrospective study. Sixty-six patients (80%) were cT1a. A strong correlation was observed between renal scintigraphy split and pre- and postoperative cortex volume split (Pearson correlation coefficient r = 0.9330 and 0.8742, respectively). The predicted eGFR correlated strongly with post 1, 3, 6, and 12 months eGFR (r = 0.8929, 0.9294, 0.9320, and 0.8952, respectively). Preoperative relative renal function and total cortex margin volume were independent risk factors for decreasing postoperative renal function.

CONCLUSION

This precise volumetric assessment that includes the resected margin is an alternative to renal scintigraphy for predicting postoperative relative renal function. The healthy cortex margin volume calculated by the reconstruction technique is an independent risk factor of decreasing postoperative renal function.

A useful method for assessing differences of compensatory hypertrophy in the contralateral kidney before and after radical nephrectomy in patients with renal cell carcinoma: ellipsoid formula on computed tomography

OBJECTIVE

To investigate the usefulness of the ellipsoid formula for assessing compensatory hypertrophy of the contralateral kidney on pre-operative and post-operative CT in renal cell carcinoma (RCC) patients.

METHODS

We retrospectively identified 389 patients who had radical nephrectomy for RCC between 2011  and 2015. Contrast-enhanced CT was performed within 3 months pre-operative and at 1 year post-operative. The kidney volumes were calculated from CT using the ellipsoid formula. We subdivided patients into three groups based on tumour size (I: ≤4 cm, II: 4-7 cm, III: >7 cm). Volumetric renal parameters were compared and multivariate analyses were performed to determine predictors associated with pre-operative  and post-operative compensatory hypertrophy.

RESULTS

Kidney volume calculation using the ellipsoid  method took a median of 51 s. Group III had a significantly larger median pre-operative contralateral renal volume than Groups I and II (I:  140.4, II: 141.6, III: 166.7 ml, p < 0.05). However, the median ratio of post-operative contralateral renal volume change was significantly higher in Groups I and II than Group III (I: 0.36, II: 0.23, III: 0.12, p < 0.001). On multivariate analysis, tumour size revealed the strongest positive association with pre-operative contralateral kidney volume (partial regression coefficient: β = 30.8, >7 cm) and ratio of post-operative contralateral kidney volume change (β  = 0.214, I vs III; β = 0.168, II vs III).

CONCLUSION

Kidney volume calculation for assessing pre- and post-operative compensatory hypertrophy of the contralateral kidney in RCC patients can be easily and rapidly performed from CT images using the ellipsoid formula. Advances in knowledge: The ellipsoid formula allows reliable method for assessing pre-operative and post-operative compensatory hypertrophy of the contralateral kidney in RCC.

Adaptive functional change of the contralateral kidney after partial nephrectomy

Partial nephrectomy aims to maintain renal function by nephron sparing; however, functional changes in the contralateral kidney remain unknown. We evaluate the functional change in the contralateral kidney using a diethylene triamine penta-acetic acid (DTPA) renal scan and determine factors predicting contralateral kidney function after partial nephrectomy. A total of 699 patients underwent partial nephrectomy, with a DTPA scan before and after surgery to assess the separate function of each kidney. Patients were divided into three groups according to initial contralateral glomerular filtration rate (GFR; group 1: <30 ml·min−1·1.73 m−2, group 2: 30–45 ml·min−1·1.73 m−2, and group 3: ≥45 ml·min−1·1.73 m−2). Multiple-regression analysis was used to identify the factors associated with increased GFR of the contralateral kidney over a 4-yr postoperative period. Patients in group 1 had a higher mean age and hypertension history, worse American Society of Anesthesiologists score, and larger tumor size than in the other two groups. The ipsilateral GFR changes at 4 yr after partial nephrectomy were −18.9, −3.6, and 3.9% in groups 1, 2, and 3, respectively, whereas the contralateral GFR changes were 10.8, 25.7, and 38.8%. Age [β: −0.105, 95% confidence interval (CI): −0.213; −0.011, P < 0.05] and preoperative contralateral GFR (β: −0.256, 95% CI: −0.332; −0.050, P < 0.01) were significant predictive factors for increased GFR of the contralateral kidney after 4 yr. The contralateral kidney compensated for the functional loss of the ipsilateral kidney. The increase of GFR in contralateral kidney is more prominent in younger patients with decreased contralateral renal function.

Benign and tumor parenchyma metabolomic profiles affect compensatory renal growth in renal cell carcinoma surgical patients

BACKGROUND AND OBJECTIVES

Pre-operative kidney volume is an independent predictor of glomerular filtration rate in renal cell carcinoma patients. Compensatory renal growth (CRG) can ensue prior to nephrectomy in parallel to tumor growth and benign parenchyma loss. We aimed to test whether renal metabolite abundances significantly associate with CRG, suggesting a causative relationship.

DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS

Tissue metabolomics data from 49 patients, with a median age of 60 years, were previously collected and the pre-operative fold-change of their contra to ipsi-lateral benign kidney volume served as a surrogate for their CRG. Contra-lateral kidney volume fold-change within a 3.3 +/- 2.1 years follow-up interval was used as a surrogate for long-term CRG. Using a multivariable statistical model, we identified metabolites whose abundances significantly associate with CRG.

RESULTS

Our analysis found 13 metabolites in the benign (e.g. L-urobilin, Variable Influence in Projection, VIP, score = 3.02, adjusted p = 0.017) and 163 metabolites in the malignant (e.g. 3-indoxyl-sulfate, VIP score = 1.3, adjusted p = 0.044) tissues that significantly associate with CRG. Benign/tumor fold change in metabolite abundances revealed three additional metabolites with that significantly positively associate with CRG (e.g. p-cresol sulfate, VIP score = 2.945, adjusted p = 0.033). At the pathway level, we show that fatty-acid oxidation is highly enriched with metabolites whose benign tissue abundances strongly positively associate with CRG, both pre-operatively and long term, whereas in the tumor tissue significant enrichment of dipeptides and benzoate (positive association), glycolysis/gluconeogenesis, lysolipid and nucleotide sugar pentose (negative associations) sub-pathways, were observed.

CONCLUSION

These data suggest that specific biological processes in the benign as well as in the tumor parenchyma strongly influence compensatory renal growth.

Automated renal cortical volume measurement for assessment of renal function in patients undergoing radical nephrectomy

BACKGROUND

Renal volume change greatly affects renal function after nephrectomy. Although various measuring techniques were reported, no standard measuring method is available. In this study, we examined the computational automated volumetric method, and evaluated the volumetric change to assess the functional outcome in patients undergoing radical nephrectomy. We developed the predictive equation for postoperative renal function from volume alternation and validated the performance.

METHODS

Thirty-two patients undergoing radical nephrectomy participated in this study. Renal volume was calculated using three different methods [ellipsoid method, conventional manual voxel count method for renal parenchyma (manual RPV), and automated voxel count method for renal cortex (automated RCV)] through newly developed imaging software. Statistical analysis was performed to evaluate the correlation between renal functional alternation 7 days after the nephrectomy and renal volumetric change. A simple predictive equation for the postoperative renal function by renal volume loss was developed and externally validated through another 12 cases.

RESULTS

The automated RCV method had the strongest correlation between renal function alternation and RCV change (R = 0.82), than manual RPV (R = 0.69) and ellipsoid method (R = 0.50). Subsequently, a simple equation for postoperative renal function by renal volume alternation was developed: predicted postoperative estimated glomerular filtration rate (eGFR) from renal volume change = preoperative eGFR × (postoperative renal volume / preoperative renal volume). In the external validation cohort, automated RCV demonstrated the predictive performance of the constructed equations for renal function (R = 0.77).

CONCLUSIONS

The computational automated RCV measurements is a simple estimation of renal functional outcome for patients undergoing radical nephrectomy.

Compensatory Structural and Functional Adaptation After Nephrectomy in Obese Patients According to Waist Circumference

OBJECTIVE

To investigate whether the postnephrectomy renal adaptation mechanism, focused on functional hyperfiltration as well as structural hypertrophy, was affected by abdominal obesity.

MATERIALS AND METHODS

We retrospectively evaluated 358 patients who underwent simple or radical nephrectomy and nephroureterectomy between 2009 and 2013. Patients were classified according to waist circumference (WC), with values >102 cm in men and >88 cm in women considered high (obesity). Functional renal volume (FRV) was measured using computed tomography performed preoperatively and 6 months postoperatively to evaluate the degree of remnant kidney hypertrophy. The degree of hyperfiltration was calculated from the difference between the preoperative and postoperative glomerular filtration rate (GFR)/FRV.

RESULTS

The mean preoperative GFR, FRV, and GFR/FRV were 72.1 mL/min/1.73 m², 282.8 cm³, and 0.25 mL/min/1.73 m²/cm³, respectively. The percent GFR reduction was significantly greater in the high WC group (high, 25.9% vs normal, 16.0%, P = .036), although the degree of hypertrophic volume in the remnant kidney showed no difference. The change in GFR/FRV was statistically lower in the high WC group (high, 25.7% vs normal, 40.2%, P = .009). The factors associated with postoperative increased GFR/FRV were low preoperative GFR, proteinuria, high predictive preserved functional parenchymal volume ratio, absence of hypertension, increased levels of high-density lipoprotein cholesterol, and normal WC (all P < .05).

CONCLUSION

Patients with high WC might have a large reduction in postoperative renal function, owing to a lower degree of functional hyperfiltration.

Validation of 3D volumetric-based renal function prediction calculator for nephron sparing surgery

OBJECTIVE

To evaluate a recently published volume-based renal function prediction calculator intended to be used in small renal mass surgical counseling.

METHODS

Retrospective data collection included three-dimensional calculation of renal mass and parenchyma of patients who have undergone extirpative therapy. The predicted glomerular filtration rate (GFR) was calculated using the online calculator. The predicted GFR was compared with the actual 6-month GFR. The Pearson correlation coefficient, paired t test and root-mean-square error (RMSE) are utilized for statistical analysis.

RESULTS

After institutional review board approval, three institutions provided data for analysis. After patients with renal mass size >300 cc, renal size >400 cc or preoperative CKD ≥stage 3 had been excluded, we retrospectively analyzed data from 136 patients. The median mass volume was 22.2 cc (IQR 7-49). In multiple linear regression analysis, the most significant variables predicting postoperative GFR were partial versus radical nephrectomy and preoperative GFR with an overall R² of .68 (F = 26.13, P < .001). The predicted GFR was 75.4 mL/min/1.73 m² compared to an actual GFR of 70.7 mL/min/1.73 m² (P < .001, paired t test). The predicted GFR was highly correlated with the actual postoperative GFR at 6 months (Pearson correlation, r = .65, P < .001). RMSE of the validation cohort was 16.87.

CONCLUSIONS

The predictive tool to determine renal function benefit of nephron sparing surgery compared to radical nephrectomy online calculator effectively predicts GFR and could potentially be used to help urologists and patients discuss renal function prior to extirpative renal surgery.

Management of Small Renal Masses: American Society of Clinical Oncology Clinical Practice Guideline

Purpose To provide recommendations for the management options for patients with small renal masses (SRMs). Methods By using a literature search and prospectively defined study selection, we sought systematic reviews, meta-analyses, randomized clinical trials, prospective comparative observational studies, and retrospective studies published from 2000 through 2015. Outcomes included recurrence-free survival, disease-specific survival, and overall survival. Results Eighty-three studies, including 20 systematic reviews and 63 primary studies, met the eligibility criteria and form the evidentiary basis for the guideline recommendations. Recommendations On the basis of tumor-specific findings and competing risks of mortality, all patients with an SRM should be considered for a biopsy when the results may alter management. Active surveillance should be an initial management option for patients who have significant comorbidities and limited life expectancy. Partial nephrectomy (PN) for SRMs is the standard treatment that should be offered to all patients for whom an intervention is indicated and who possess a tumor that is amenable to this approach. Percutaneous thermal ablation should be considered an option if complete ablation can reliably be achieved. Radical nephrectomy for SRMs should only be reserved for patients who possess a tumor of significant complexity that is not amenable to PN or for whom PN may result in unacceptable morbidity even when performed at centers with expertise. Referral to a nephrologist should be considered if chronic kidney disease (estimated glomerular filtration rate < 45 mL/min/1.73 m²) or progressive chronic kidney disease occurs after treatment, especially if associated with proteinuria.

Compensatory Hypertrophy After Living Donor Nephrectomy

BACKGROUND

Previous studies have shown that kidney volume enhances the estimation of glomerular filtration rate (eGFR) in kidney donors. This study aimed to describe the phenomenon of compensatory hypertrophy after donor nephrectomy as measured on computerized tomographic (CT) scans.

METHODS

An institutional Domain Specific Review Board (DSRB)-approved study involved approaching kidney donors to have a follow up CT scan from 6 months to 1 year after surgery; 29 patients participated; 55% were female. Clinical chart review was performed, and the patient's remaining kidney volume was measured before and after surgery based on CT scans. eGFR was determined with the use of the Modification of Diet in Renal Disease equation.

RESULTS

Mean parenchymal volume of the remaining kidney for this population (mean age, 44.3 ± 8.5 y) was 204.7 ± 82.5 cc before surgery and 250.5 ± 113.3 cc after donor nephrectomy. Compensatory hypertrophy occurred in 79.3% of patients (n = 23). Mean increase in remaining kidney volume was 22.4 ± 23.2% after donor nephrectomy in healthy individuals. Over a median follow-up of 52.9 ± 19.8 months, mean eGFR was 68.9 ± 12.4 mL/min/1.73 m(2), with 24.1% of patients (n = 7) in chronic kidney disease grade 3. Absolute and relative change in kidney volume was not associated with sex, race, surgical approach, or background of hypertension (P = NS). There was a trend of decreased hypertrophy with increasing age (P = .5; Spearman correlation, -0.12).

CONCLUSIONS

In healthy kidney donors, compensatory hypertrophy of the remaining kidney occurs in 79.3% of the patients, with an average increment of about 22.4%. Older patients may have a blunted compensatory hypertrophy response after surgery.

The effect of contralateral kidney volume on renal function after radical nephroureterectomy: Implications for eligibility for neoadjuvant chemotherapy for upper tract urothelial cancer

PURPOSE

We investigated the effect of preoperative contralateral kidney (CK) volume on renal function after radical nephroureterectomy (RNU).

METHODS

We reviewed 630 patients who underwent RNU between September 1994 and December 2013. Of these 630 patients, 135 patients with advanced upper tract urothelial cancer were ultimately included. Preoperative CK volume was measured from computed tomography images of the venous phase using a specialized volumetric program. Glomerular filtration rate (GFR) was calculated using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations and checked preoperatively, 7 days, 1, 3, and 12 months postoperatively.

RESULTS

The mean age at surgery was 62.1 (10.1) years and the mean CKD-EPI GFR was 73.8 (75.5) ml/min/1.73m². After RNU, new-onset CKD was identified in 69 (51.1%) patients. On multivariate logistic regression analysis, high body mass index (95% CI: 1.08-1.51, P = 0.005), low preoperative CKD-EPI GFR (95% CI: 0.92-0.98, P = 0.037), and low CK volume (95% CI: 0.96-0.99, P<0.001) were associated with new-onset CKD at 1 month after RNU. There was a positive correlation between CK volume and CKD-EPI GFR at 1 month after RNU (Spearman ρ = 0.495, P<0.001). When stratified according to CK volume, CK volume less than 150ml was significantly associated with new-onset CKD after RNU (95% CI: 2.49-26.29, P = 0.001).

CONCLUSIONS

High body mass index, low preoperative CKD-EPI GFR, and low CK volume are significantly associated with new-onset CKD. Therefore, they could be used to identify patients eligible for neoadjuvant chemotherapy in upper tract urothelial cancer.

Three-dimensional reconstructive kidney volume analyses according to the endophytic degree of tumors during open partial or radical nephrectomy

Objectives

To investigate the renal function outcomes and contralateral kidney volume change measured by using a 3-dimensional reconstructive method after open partial nephrectomy (PN) or open radical nephrectomy (RN) according to the endophytic degree of tumors.

Materials and Methods

We included 214 PN and 220 RN patients. According to the endophytic degree of the tumors, we divided patients into 3 groups. Patients were assessed for renal function and kidney volume change both preoperatively and postoperatively at 6 months. Kidney volume was calculated by using personal computer-based software. Subgroup analyses was performed for tumor >4cm.

Results

Larger and complex tumors were more frequent in the RN group than PN group. Among patients with exophytic and mild endophytic tumors, the mean postoperative renal function was well preserved in PN group and the mean contralateral kidney volume significantly increased in the RN compared to the PN group (PN, 145.55 to 149.98mL; 3.0% versus RN, 143.93 to 169.64mL;17.9% p=0.006). However, in fully endophytic tumors, compensatory hypertrophy of the contralateral kidney was similar between PN and RN (PN, 138.16 to 159.64mL; 15.5 % versus RN, 138.65 to 168.04mL; 21.2% p=0.416) and renal functional outcomes were similar between both groups. These results were also confirmed in tumors >4cm in size.

Conclusions

In fully endophytic tumors, especially large tumors, the postoperative renal function and contralateral kidney volume were similar; therefore, we should consider RN preferentially as surgical option for these tumors.

Parenchymal Volumetric Assessment as a Predictive Tool to Determine Renal Function Benefit of Nephron-Sparing Surgery Compared with Radical Nephrectomy

PURPOSE

To develop a preoperative prediction model using a computer-assisted volumetric assessment of potential spared parenchyma to estimate the probability of chronic kidney disease (CKD, estimated glomerular filtration rate [eGFR] <60 mL/min/1.73 m(2)) 6 months from extirpative renal surgery (nephron-sparing surgery [NSS] or radical nephrectomy [RN]).

PATIENTS AND METHODS

Retrospective analysis of patients who underwent NSS or RN at our institution from January 2000 to June 2013 with a compatible CT scan 6-month renal function follow-up was performed. Primary outcome was defined as the accuracy of 6-month postoperative eGFR compared with actual postoperative eGFR based on root mean square error (RMSE). Models were constructed using renal volumes and externally validated. A clinical tool was developed on the best model after a given surgical procedure using area under the curve (AUC).

RESULTS

We identified 130 (51 radical, 79 partial) patients with a median age of 58 years (interquartile range [IQR] 48-67) and preoperative eGFR of 82.1 (IQR 65.9-104.3); postoperative CKD (eGFR <60) developed in 42% (55/130). We performed various linear regression models to predict postoperative eGFR. The Quadratic model was the highest performing model, which relied only on preoperative GFR and the volumetric data for a RMSE of 15.3 on external validation corresponding to a clinical tool with an AUC of 0.89.

CONCLUSION

Volumetric-based assessment provides information to predict postoperative eGFR. A tool based on this equation may assist surgical counseling regarding renal functional outcomes before renal tumor surgical procedures.

Preoperative Renal Volume: A Surrogate Measure for Radical Nephrectomy-Induced Chronic Kidney Disease

OBJECTIVES

Surgically induced chronic kidney disease (CKD) has been found to have less impact on survival as well as function when compared to medical causes for CKD. The aim of this study is to evaluate whether preoperative remaining kidney volume correlates with renal function after nephrectomy, which represents an individual's renal reserve before surgically induced CKD.

METHODS

A retrospective review of 75 consecutive patients (29.3% females) who underwent radical nephrectomy (RN) (2000-2010) was performed. Normal side kidney parenchyma, excluding renal vessels and central sinus fat, was manually outlined in each transverse slice of CT image and multiplied by slice thickness to calculate volume. Estimated glomerular filtration rate (eGFR) was determined using the Modification of Diet in Renal Disease equation. CKD is defined as eGFR < 60 mL/min/1.73 m(2).

RESULTS

Mean preoperative normal kidney parenchymal volume (mean age 55 [SD 13] years) is 150.7 (SD 36.4) mL. Over median follow-up of 36 months postsurgery, progression to CKD occurred in 42.6% (n = 32) of patients. On multivariable analysis, preoperative eGFR and preoperative renal volume <144 mL are independent predictors for postoperative CKD. On Kaplan-Meier analysis, median time to reach CKD postnephrectomy is 12.7 (range 0.03-43.66) months for renal volume <144 mL but not achieved if renal volume is >144 mL.

CONCLUSIONS

Normal kidney parenchymal volume and preoperative eGFR are independent predictive factors for postoperative CKD after RN and may represent renal reserve for both surgically and medically induced CKD, respectively. Preoperative remaining kidney volume may be an adjunct representation of renal reserve postsurgery and predict later renal function decline due to perioperative loss of nephrons.

Renal cell carcinoma: risks and benefits of nephron-sparing surgery for T1 tumors

Renal cell carcinoma is the most common cancer of the kidneys that is primarily treated with surgery, including removal of part or all the involved kidney depending on size and tumor, complexity, and patient characteristics. Partial nephrectomy historically was restricted to cases of solitary kidney or bilateral tumors. It was then started for masses smaller than 4 cm and currently is even studied and justified in tumors smaller than 7 cm if surgically feasible. Although partial nephrectomy preserves kidney tissue and, therefore, delays or prevents the new onset of CKD and ESRD, radical nephrectomy is still overused even for the small tumors. Studies have shown that although this practice is driven by an easier complete removal of the kidney especially in the era of minimally invasive surgery, partial nephrectomy is successful in curing cancer and achieving excellent cancer-specific survival in addition to its benefits on cardiovascular health. Nowadays interest in preserving healthy kidney tissue is increasing to the level of studying the impact of larger volume removed around the kidney and the histopathology of that non-neoplastic tissue to predict kidney function behavior postoperatively.

Compensatory Structural and Functional Adaptation after Radical Nephrectomy for Renal Cell Carcinoma According to Preoperative Stage of Chronic Kidney Disease

PURPOSE

We investigated structural hypertrophy and functional hyperfiltration as compensatory adaptations after radical nephrectomy in patients with renal cell carcinoma according to the preoperative chronic kidney disease stage.

MATERIALS AND METHODS

We retrospectively identified 543 patients who underwent radical nephrectomy for renal cell carcinoma between 1997 and 2012. Patients were classified according to preoperative glomerular filtration rate as no chronic kidney disease--glomerular filtration rate 90 ml/minute/1.73 m(2) or greater (230, 42.4%), chronic kidney disease stage II--glomerular filtration rate 60 to less than 90 ml/minute/1.73 m(2) (227, 41.8%) and chronic kidney disease stage III--glomerular filtration rate 30 to less than 60 ml/minute/1.73 m(2) (86, 15.8%). Computerized tomography performed within 2 months before surgery and 1 year after surgery was used to assess functional renal volume for measuring the degree of hypertrophy of the remnant kidney, and the preoperative and postoperative glomerular filtration rate per unit volume of functional renal volume was used to calculate the degree of hyperfiltration.

RESULTS

Among all patients (mean age 56.0 years) mean preoperative glomerular filtration rate, functional renal volume and glomerular filtration rate/functional renal volume were 83.2 ml/minute/1.73 m(2), 340.6 cm(3) and 0.25 ml/minute/1.73 m(2)/cm(3), respectively. The percent reduction in glomerular filtration rate was statistically significant according to chronic kidney disease stage (no chronic kidney disease 31.2% vs stage II 26.5% vs stage III 12.8%, p <0.001). However, the degree of hypertrophic functional renal volume in the remnant kidney was not statistically significant (no chronic kidney disease 18.5% vs stage II 17.3% vs stage III 16.5%, p=0.250). The change in glomerular filtration rate/functional renal volume was statistically significant (no chronic kidney disease 18.5% vs stage II 20.1% vs stage III 45.9%, p <0.001). Factors that increased glomerular filtration rate/functional renal volume above the mean value were body mass index (p=0.012), diabetes mellitus (p=0.023), hypertension (p=0.015) and chronic kidney disease stage (p <0.001).

CONCLUSIONS

Patients with a lower preoperative glomerular filtration rate had a smaller reduction in postoperative renal function than those with a higher preoperative glomerular filtration rate due to greater degrees of functional hyperfiltration.

A comparison of radiologic tumor volume and pathologic tumor volume in renal cell carcinoma (RCC)

OBJECTIVE

To investigate the difference between preoperative radiologic tumor volume (RTV) and postoperative pathologic tumor volume (PTV) in patients who received nephrectomy for renal cell carcinoma (RCC).

MATERIALS AND METHODS

We reviewed 482 patients who underwent preoperative computed tomography (CT) within 4 weeks before radical or partial nephrectomy for renal cell carcinoma. RTV measured by a three dimensional rendering program was compared with PTV (π/6 x height x length x width) measured in surgical specimen according to pathologic tumor size and histologic subtype. Correlation of the inter-quartile range (IQR) of the RTV and Fuhrman nuclear grade was also investigated.

RESULTS

There was a significant positive linear correlation between RTV and PTV (p < 0.001, r = 0.911), and the mean RTV and mean PTV were not significantly different (79.0 vs 76.9 cm3, p = 0.393). For pathologic tumor size (PTS) < 4 cm, the mean RTV was larger than the mean PTV (10.9 vs 7.1 cm3, p < 0.001). For a PTS of 4-7 cm, the mean RTV was larger than the mean PTV (56.0 vs 44.7 cm3, p < 0.001). However, for a PTS ≥ 7 cm, there was no statistical difference between RTV and PTV (p > 0.05). Among patients with clear cell RCC, the mean RTV was significantly larger than the mean PTV (p = 0.042), not for non-clear cell group (p = 0.055). As the quartile of the RTV increased, the Fuhrman grade also increased (p < 0.001).

CONCLUSIONS

RTV was correlated with PTV and pathologic grade. RTV was larger than the PTV for a tumor size 7 cm or less or in clear cell RCC. RTV may be useful to measure tumor burden preoperatively.

Feasibility of omitting cortical renorrhaphy during robot-assisted partial nephrectomy: a matched analysis

BACKGROUND AND PURPOSE

To assess the safety of omitting cortical renorrhaphy during robot-assisted partial nephrectomy and measure preliminary functional outcomes.

PATIENTS AND METHODS

Fifteen robot-assisted partial nephrectomies were performed with a running, base-layer suture for the collecting system and vessel hemostasis but without cortical renorrhaphy. The nonrenorrhaphy group was matched 1:2 by R.E.N.A.L. nephrometry score to a running, sliding-clip cortical renorrhaphy group retrospectively. Intraoperative blood loss, urine leaks, postoperative bleeds, and functional outcomes were evaluated. Predictors of %volume loss were evaluated using multivariable regression.

RESULTS

No differences were seen between renorrhaphy and nonrenorrhaphy in sex (P=0.53), age (P=0.14), body mass index (P=0.08), Charlson score (P=0.44), tumor diameter (P=0.55), nephrometry score (P=0.77), preoperative glomerular filtration rate (GFR, P=0.63), or the amount of resected healthy kidney margin (P=0.21). Warm ischemia time was less for the nonrenorrhaphy group (P<0.002). One pseudoaneurysm necessitating embolization (1/30=3%) was seen in the renorrhaphy group compared with none in the nonrenorrhaphy group. No urine leaks occurred in either group. The median %GFR loss was 8.8% for renorrhaphy and 4.4% for nonrenorrhaphy (P=0.14) at a median follow-up of 4.1 months. The median %volume loss was 17 cm(3) for renorrhaphy and 9 cm(3) for nonrenorrhaphy (P=0.003). In a multivariable model, both cortical renorrhaphy (P=0.004) and tumor diameter (P=0.004) were predictors of %volume loss.

CONCLUSION

Omission of cortical renorrhaphy appears feasible with no urine leaks or bleeding complications observed. The percent renal volume loss was improved by omission of cortical renorrhaphy. Reconstruction technique is important to control for when studying renal function after partial nephrectomy.

Decline in renal function after partial nephrectomy: etiology and prevention

PURPOSE

Partial nephrectomy is the reference standard for the management of small renal tumors and is commonly used for localized kidney cancer. A primary goal of partial nephrectomy is to preserve as much renal function as possible. New baseline glomerular filtration rate after partial nephrectomy can have prognostic significance with respect to long-term outcomes. Recent studies provide an increased understanding of the factors that determine functional outcomes after partial nephrectomy as well as preventive measures to minimize functional decline. We review these advances, highlight ongoing controversies and stimulate further research.

MATERIALS AND METHODS

A comprehensive literature review consistent with the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) criteria was performed from January 2006 to April 2014 using PubMed®, Cochrane and Ovid Medline. Key words included partial nephrectomy, renal function, warm ischemia, hypothermia, nephron mass, parenchymal volume, surgical approaches to partial nephrectomy, preoperative and intraoperative imaging, enucleation, hemostatic agents and energy based resection. Relevant reviews were also examined as well as their cited references. An additional Google Scholar search was conducted to broaden the scope of the review. Only English language articles were included in the analysis. The primary outcomes of interest were the new baseline level of function after early postoperative recovery, percent decline in function, potential etiologies and preventive measures.

RESULTS

Decline in function after partial nephrectomy averages approximately 20% in the operated kidney, and can be due to incomplete recovery from the ischemic insult or loss of nephron mass related to parenchymal excision or collateral damage during reconstruction. Compensatory hypertrophy in the contralateral kidney after partial nephrectomy in adults is marginal and decline in global renal function for patients with 2 kidneys averages about 10%, although there is some variance based on tumor size and location. Irreversible ischemic injury can be minimized by pharmacological intervention or surgical approaches such as hypothermia, limited warm ischemia, or zero or segmental ischemia. Excessive loss of nephron mass can be minimized by improved preoperative or intraoperative imaging, use of a bloodless field, enucleation and vascular microdissection. Hemostatic agents or energy based resection that minimizes the need for parenchymal and capsular suturing can also optimize preservation of the vascularized nephron mass.

CONCLUSIONS

Our understanding of the decline in renal function after partial nephrectomy has advanced considerably, including better appreciation of its magnitude and impact in various settings, possible etiologies and potential preventive measures. Many controversies persist and this remains an important area of investigation.

Volumetry may predict early renal function after nephron sparing surgery in solitary kidney patients

We investigate the impact of the residual kidney volume measured by tumor volumetry on preoperative imaging in predicting post-operative renal function. Nephron sparing surgery (NSS) in renal cell carcinoma (RCC) is the standard treatment for T1 kidney tumors. Resection of kidney tumors in solidary kidneys needs precise preoperative counseling of patients regarding post-operative renal function.

Patients planned for renal tumor surgery who underwent prior nephrectomy on the contralateral side were included. We identified 35 patients in our database that underwent NSS in solitary kidneys and met the inclusion criteria. Tumor volumetry was performed on computer tomography (CT) or magnetic resonance imaging (MRI) with the Medical Imaging Interaction Toolkit (MITK). Clinical and pathological data were assessed. Follow-up data included renal function over 3 years.

Mean age was 64 ± 8.1 years. Mean tumor volume on imaging was 27.5 ± 48.6 cc. Mean kidney volume was 195.2 ± 62.8 cc and mean residual kidney volume was 173.4 ± 65.3 cc. We found a correlation between renal function (MDRD) and residual kidney volume on imaging 1-week post-surgery (p = 0.038). Mid- and long-term renal function was not associated with residual kidney volume.

In conclusion, renal volumetry may predict early renal function after NSS.

Simplified method to measure renal volume: the best correction factor for the ellipsoid formula volume calculation in pretransplant computed tomographic live donor

OBJECTIVE

To find an optimal correction factor that will produce a near-real renal volume calculation using the ellipsoid formula.

METHODS

We retrospectively studied 79 multidetector computed tomography (MDCT) examinations for potential renal donor assessment. The renal volumes were calculated using the slice summation method, the ellipsoid formula with π/6 as correction factors as well multiple other correction factors for statistical analysis. A paired Student t test was used for evaluating the volumes calculated with different correction factors and the volumes calculated by the slice summation method.

RESULTS

The ellipsoid formula using correction factor 0.524 underestimates the renal volume by approximately 22.2% with statistical difference compared with the slice summation method (P<.05). There is no statistical difference when using correction factor in the range of 0.664 to 0.686 (P>.05). Further subgroup analysis of gender and laterality was performed and revealed no statistical difference. Using a mean value of 0.674 or 0.67 as correction factor results in renal volumes that are 100% and 99.5%.

CONCLUSION

To avoid underestimation of the renal volume by the ellipsoid method, acceptable correction factors are in the range of 0.664 to 0.686. We suggest the use of a mean value of 0.674 or 0.67 as correction factor when using the ellipsoid formula.

Compensatory hypertrophy after partial and radical nephrectomy in adults

PURPOSE

We assessed compensatory hypertrophy in the contralateral kidney after partial and radical nephrectomy in adults. We also examined predictive factors to facilitate more accurate estimation of global renal function after surgery.

MATERIALS AND METHODS

We analyzed the records of 172 patients who underwent partial or radical nephrectomy with appropriate studies to determine function and parenchymal mass specifically in the operated and contralateral kidneys. All patients required renal scans to provide split renal function preoperatively and postoperatively. Parenchymal volume was measured by computerized tomography. All studies were done less than 2 months preoperatively and 4 to 12 months postoperatively.

RESULTS

A total of 113 and 59 patients underwent partial and radical nephrectomy, and median tumor size was 3.5 and 7.0 cm, respectively (p <0.0001). Of patients treated with partial nephrectomy 19% had high complexity tumor compared to 80% of those treated with radical nephrectomy (p <0.0001). Median ipsilateral parenchymal volume was reduced 18% after partial nephrectomy and the median glomerular filtration rate in this kidney decreased 24.4%. The median contralateral kidney function increase after partial nephrectomy was 2.3% vs 21.1% after radical nephrectomy (p <0.0001). Median global function decreased 9.6% after partial nephrectomy vs 32.2% after radical nephrectomy (p <0.0001). A larger percent parenchymal volume loss (p = 0.0001) and fewer comorbidities (p = 0.0072) significantly correlated with greater compensatory hypertrophy in the contralateral kidney on multivariable analysis.

CONCLUSIONS

Compensatory hypertrophy in adults was limited after partial nephrectomy and it correlated significantly with the amount of parenchymal volume excised. Healthier patients also appeared to respond better. These results may allow for more accurate estimation of global renal function after partial and radical nephrectomy.