Assessing renal function after partial nephrectomy using renal nuclear scintigraphy and estimated glomerular filtration rate

The Nephrologist's Management of Renal Cell Carcinoma After Kidney Surgery

Renal cell carcinoma is associated with chronic kidney disease as well as with common risk factors including hypertension and diabetes mellitus. Localized renal cell carcinoma is treated surgically and in these cases has a favorable prognosis. In particular, in those individuals with small renal masses (≤4 cm), preservation of kidney function should be prioritized. Postoperative chronic kidney disease or end-stage renal disease prevention should include baseline kidney function and risk factor assessment, nontumor renal biopsy, as well as counseling on treatment options to discuss maximizing kidney function preservation. Postnephrectomy prognosis can be determined with repeat laboratory and clinical assessment. Ultimately, early involvement of the nephrologist in a multidisciplinary team including the urology team will enable the reduction of postsurgical kidney disease related morbidity and potentially mortality.

Toward Individualized Approaches to Partial Nephrectomy: Assessing the Correlation Between Ischemia Time and Patient Health Status (RECORD2 Project)

BACKGROUND

Ischemia time during partial nephrectomy (PN) is among the greatest determinants of acute kidney injury (AKI). Whether this association is affected by the preoperative risk of AKI has never been investigated.

OBJECTIVE

To assess the effect of the interaction between the preoperative risk of AKI and ischemia time on the probability of AKI during PN.

DESIGN, SETTING, AND PARTICIPANTS

Data of 944 patients treated with on-clamp PN for cT1 renal tumors were extracted from the Registry of Conservative and Radical Surgery for Cortical Renal Tumor Disease (RECORD2) database, a prospective multicenter project.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

We estimated the preoperative risk of AKI (defined according to the risk/injury/failure/loss/end-stage [RIFLE] criteria) according to age, baseline renal function, clinical stage, preoperative aspects and dimensions used for an anatomical (PADUA) score, and surgical approach. Classification and regression tree (CART) analysis identified patients at "high" and "low" risk of AKI. Finally, we plotted the probability of AKI over ischemia time stratified by the preoperative risk of AKI.

RESULTS AND LIMITATIONS

Overall, 235 (25%) patients experienced AKI after surgery. At multivariable analysis, older patients, those with more complex tumors, those with higher baseline function, and those treated with open surgery had an increased risk of AKI (all p ≤ 0.011). According to the first split at CART analysis, patients were categorized as those with "high" and "low" risk of AKI having a probability of >40% or <40%. For low-risk patients, the probability of AKI in case of <10 versus >20 min of ischemia was 13% versus 28% (absolute risk increase 15%). The risk of AKI for high-risk patients who had <10 versus >20 min of ischemia was 31% versus 77%. This corresponds to an absolute risk increase of 45%. Limitations include retrospective data analyses and lack of surgeons' prior experience.

CONCLUSIONS

Ischemia time during PN has different implications for patients with different health status. Clamp time seems less clinically relevant for patients in good conditions who may endure prolonged ischemia with a mild increase in the risk of AKI, whereas frail patients seem to be more vulnerable to ischemic damage even for short clamp time. For individualized intra- and postoperative management, duration of ischemia needs to be questioned in the context of the individual health status.

PATIENT SUMMARY

Functional sequelae related to ischemia time during partial nephrectomy depend on baseline health status. The correlation between the duration of ischemia and baseline health status should be taken into account toward individualized intra- and postoperative management.

Robot-Assisted Laparoscopic Partial Nephrectomy Vs Conventional Laparoscopic Partial Nephrectomy: Functional and Surgical Outcomes of a Prospective Single Surgeon Randomized Study

Background: Laparoscopic partial nephrectomy (LPN) and robot-assisted partial nephrectomy (RAPN) are commonly used techniques for treating small renal masses. Regarding renal function (RF) preservation, no superiority of one technique over the other has yet been definitely demonstrated. Objective: To compare functional and surgical outcomes of LPN and RAPN. Patients and Methods: Between 2015 and 2019, we prospectively randomized 115 patients with cT1-T2 renal masses to LPN in total ischemia or RAPN in selective ischemia. Primary endpoint was RF preservation, assessed by renal scintigraphy (RS). RS assessments were performed preoperatively and at 6 months follow-up. Secondary endpoints included clinical, histopathologic, and surgical outcomes. Results: One hundred eight patients were included in the final analysis. Patient and tumor characteristics were comparable. No significant difference in RS values after 6 months was observed between both groups. Median (interquartile range) RF change after 6 months was -18.0% (-26.5 to -11.0) in LPN group and -20.0 (-33.2 to -12.0) in RAPN group (p = 0.3). Mean (standard deviation [SD]) warm ischemia time was 21.1 (6.1) minutes in LPN group and 19.6 (7.7) minutes in RAPN group (p = 0.2). No positive surgical margins (PSMs) occurred in the LPN group, whereas RAPN group had PSM in 4.9% (n = 3); p = 0.099. Renal volume loss after 6 months was 27.5% (22.7-45.7) in the LPN group vs 37.5 (13.7-54.2) in the RAPN group (p = 0.5). Mean operative times were lower in the LPN group (192.3 minutes [SD 44.5] vs 230.2 minutes [SD 59.6], p = 0.001). More complications occurred in the LPN group (31% vs 21%, p = 0.075). Transfusion rates were 15% for LPN and 11% for RAPN. Conclusions: In terms of preserving RF, LPN in total ischemia and RAPN in selective ischemia are comparable. In most patients, RF decrease of the affected kidney after PN seems to not exceed 25%, regardless of the surgical approach.

The role of RENAL, PADUA, C-index, CSA nephrometry systems in predicting ipsilateral renal function after partial nephrectomy

Background

Functional outcome is an important issue in nephron-sparing surgery. Various nephrometries have been developed to predict renal function preservation. The aim of this study was to examine the applicability of R.E.N.A.L., PADUA, C-index, and mathematical tumor contact surface area (CSA) in predicting ipsilateral renal function after partial nephrectomy using radio-isotope scans.

Methods

We performed this retrospective study in patients who underwent partial nephrectomy between May 2013 and April 2017, and used abdominopelvic computerized tomography or magnetic resonance imaging to obtain R.E.N.A.L., C-index, and CSA. Renal function was measured by 99mTc mercaptoacetyltriglycine (MAG3). We evaluated correlations between nephrometries and perioperative parameters, and comparatively analyzed different nephrometries to determine the predictive ability in the percent change of effective renal plasma flow of the affected kidney.

Results

Three, two, and 35 patients received partial nephrectomy in open, laparoscopic, and robotic approaches, respectively. The median (IQR) tumor size was 3.13 (2.4) cm. The median (IQR) R.E.N.A.L., PADUA, C-index, and CSA scores were 7 (3), 8 (2), 2.01 (1.87), and 14.14 (19.25) cm², respectively. Spearman correlation analysis showed that four nephrometries were correlated with each other. The strongest correlations were between CSA and C-index (coefficient: − 0.885, p < 0.001), followed by R.E.N.A.L. and PADUA (coefficient: 0.778, p < 0.001). Ischemia time was significantly correlated with R.EN.A.L. (coefficient: 0.35, p = 0.025), PADUA (coefficient: 0.42, p = 0.007), C-index (coefficient: − 0.45, p = 0.004), and CSA (coefficient: 0.41, p = 0.009). In multivariate analysis, PADUA significantly affected ischemia time (p = 0.04). The percent change in effective renal plasma flow (PCE) of the operated kidney was correlated with PADUA (coefficient: 0.48 p = 0.002), C-index (coefficient: − 0.74, p < 0.001), and CSA (coefficient: 0.75, p < 0.001). Only CSA and C-index independently affected PCE (both p < 0.05) in multivariate analysis. In ROC curve analysis, both C-index and CSA could predict 20% change in effective renal plasma flow (AUC: 0.91 vs 0.86, p = 0.2) of the affected kidney.

Conclusions

We suggest using PADUA to evaluate surgical complexity and ischemia time. Regarding the accuracy of the prediction of post-operative ipsilateral renal function, both CSA and C-index outperformed R.E.N.A.L. and PADUA nephrometries.

The superiority of contact surface area as a predictor of renal cortical volume change after partial nephrectomy compared to RENAL, PADUA and C-index: an approach using computed tomography-based renal volumetry

Objective: To evaluate the renal cortical volume (RCV) change after nephron sparing surgery and the predictive value of the nephrometry score in RCV preservation after partial nephrectomy. Materials and methods: Overall, 162 patients with renal tumors that were treated with open partial nephrectomy were retrospectively analyzed. The contact surface area (CSA), RENAL, PADUA and C-index scores were obtained from a preoperative CT scan. The RCV of the tumor-bearing kidney was measured preoperatively and postoperatively using dedicated software. The correlation between the four nephrometry scores and perioperative parameters were evaluated and the scores were compared in terms of their ability to predict a reduction in the RCV. Results: All scores showed a significant association with reduction in RCV (all p < 0.001), percent reduction in RCV (all p < 0.001) and estimated blood loss (all p < 0.05). Only the CSA and PADUA scores showed a significant association with percent reduction in eGFR (p = 0.038 and p = 0.026, respectively). On multivariate analysis, the CSA, PADUA and C-index scores independently affected the percent reduction in RCV (p = 0.003, p = 0.025 and p = 0.013, respectively). On ROC curve analysis, CSA was a better independent predictor of a greater than 10% and 20% reduction in the RCV (AUC 0.87 and 0.72, respectively). Conclusion: CT-based RCV measurement successfully differentiated the RCV change after partial nephrectomy. Compared to the other three nephrometry scores, CSA was a superior predictor of RCV change in the operated kidney.

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.

The preoperative stratification of patients based on renal scan data is unable to predict the functional outcome after partial nephrectomy

INTRODUCTION

eGFR-categories are used to predict functional outcome after partial nephrectomy (PN); no study categorized patients according to preoperative renal scan (RS) data. Aim of the study was to evaluate if stratification of patients according to RS is a reliable method to predict minor/major loss of renal function after PN.

MATERIALS AND METHODS

We considered patients who underwent PN and RS pre-/post-PN for T1 tumor in our Institution (2007-2017). Demographics, perioperative and specifically functional data were analysed. On the basis of the baseline Split Renal Function (SRF), patients were stratified into risk-categories: 1) baseline operated-kidney SRF range 45-55%; 2) baseline operated-kidney SRF < 45%. Risk categories were analysed with postoperative functional outcome: postoperative operated-kidney SRF decrease below 90% of baseline was considered significant loss of function. Contingency tables and univariate/multivariate regression were analysed looking for independent factors of postoperative functional impairment.

RESULTS

224 patients were analysed, 125 (55.8%) maintained >90% of their baseline function. Worse probability of maintaining ≥90 baseline renal function was found in patients with Charlson's Comorbidity Index (CCI≥3) (p=0.004) and patients with PADUA score ≥8 (p=0.023). After stratification by baseline renal function, ischemia was the only independent factor: no effect on patients with poorer baseline renal function. Patients with baseline SRF 45-55% who did not experience ischemia had the highest probability to maintain ≥90% baseline SRF (p=0.028). Ischemia >25 minutes was detrimental (p=0.017).

CONCLUSIONS

Stratification of patients by SRF before PN is not a reliable predictor of renal functional outcome. Ischemia seems to scarcely influence patients with poorer renal function.

Prospective study of robotic partial nephrectomy for renal cancer in Japan: Comparison with a historical control undergoing laparoscopic partial nephrectomy

OBJECTIVES

To evaluate the outcomes of robotic partial nephrectomy compared with those of laparoscopic partial nephrectomy for T1 renal tumors in Japanese centers.

METHODS

Patients with a T1 renal tumor who underwent robotic partial nephrectomy were eligible for inclusion in the present study. The primary end-point consisted of three components: a negative surgical margin, no conversion to open or laparoscopic surgery and a warm ischemia time ≤25 min. We compared data from these patients with the data from a retrospective study of laparoscopic partial nephrectomy carried out in Japan.

RESULTS

A total of 108 patients were registered in the present study; 105 underwent robotic partial nephrectomy. The proportion of patients who met the primary end-point was 91.3% (95% confidence interval 84.1-95.9%), which was significantly higher than 23.3% in the historical data. Major complications were seen in 19 patients (18.1%). The mean change in the estimated glomerular filtration rate in the operated kidney, 180 days postoperatively, was -10.8 mL/min/1.73 m² (95% confidence interval -12.3-9.4%).

CONCLUSIONS

Robotic partial nephrectomy for patients with a T1 renal tumor is a safe, feasible and more effective operative method compared with laparoscopic partial nephrectomy. It can be anticipated that robotic partial nephrectomy will become more widely used in Japan in the future.

Robot-assisted partial nephrectomy: systematic review of functional results

PURPOSE OF REVIEW

Various ischemia type during partial nephrectomy for renal cell cancer (RCC) resulted in different postoperative functional outcomes. Our objective was to systematically review the contemporary literature on robot-assisted partial nephrectomy (RPN) and investigate the association of ischemia type and tumor complexity with postoperative functional outcomes of the operated kidney and overall.

RECENT FINDINGS

Forty-five of the 99 reports identified were selected for qualitative analysis. All included studies were observational and nonrandomized. Overall, we found that patients undergoing RPN with zero ischemia and selective artery clamping had a lower decrease in glomerular filtration rates of the operated kidney in comparison to both warm and cold ischemia. This association seems also to play a role in patients with bilateral kidneys harboring complex tumors.

SUMMARY

Zero ischemia and selective artery clamping provide the best functional outcomes following robotic partial nephrectomy. This seems to be of particular relevance in patients with single kidney or tumors of high complexity. Whether these changes are statistically or clinically significant cannot be determined within this systematic review.

The impact of T1 renal tumor characteristics on baseline renal function in patients undergoing partial nephrectomy: A renal scan based objective assessment

INTRODUCTION AND OBJECTIVES

To objectively assess the impact of renal tumors characteristics and other measurable factors on baseline renal function in patient undergoing partial nephrectomy (PN).

METHODS

Patients who underwent laparoscopic PN for a T1 renal mass between 2012 and 2016 and who also had a mercapto-acetyltriglycine renal scan prior to surgery were retrieved from a single institution prospectively-collected database. Split renal function (SRF) and Effective Renal Plasma Flow (ERPF) for both the operated kidney and the unaffected contralateral were calculated. Patient demographics and tumor characteristics (e.g. size, location and; nephrometry score) were assessed. Renal function of both the operated and the unaffected; contralateral kidney were compared. Statistical analysis was performed by using Statistica 8.0 (StatSoft).

RESULTS

227 patients were deemed eligible and included in the analysis. Univariable analysis showed a significant impact of age-adjusted CCI (p = 0.027), hypertension (p = 0.031) and age (p < 0.001) on operated kidney ERPF. Gender (p = 0.011), hypertension (p = 0.042), CCI (both standard and age-adjusted, p = 0.021 and = 0.003, respectively) and age (p < 0.001) were significantly; associated with contralateral unaffected kidney ERPF. Multivariable analysis confirmed age (p < 0.001) and hypertension (p < 0.021) as independent factors in both the operated and the unaffected kidney.

CONCLUSIONS

Characteristics of the renal mass (including nephrometry score and size) seem to have no clinically relevant impact on baseline renal function in patients undergoing partial nephrectomy for cT1 renal tumors. Age, hypertension and co-morbidities confirm to represent un-modifiable significant factors influencing baseline renal function.

Effect of median household income on surgical approach and survival in renal cell carcinoma

PURPOSE

We sought to determine whether median household income (MHI) independently predicts surgical approach (partial vs. radical nephrectomy) and survival in patients with renal cell carcinoma.

METHODS

The U.S. Surveillance Epidemiology and End Results Database (1988-2011) was queried to examine kidney cancer cases and linked to the Area Health Resources File. We correlated surgical approach and survival, both overall and cancer-specific, with tumor stage, age, race, sex, and income data.

RESULTS

Of 152,589 patients diagnosed with renal cell carcinoma, 24,221 (16%) patients underwent partial nephrectomy, 102,771 (67%) patients underwent radical nephrectomy, and 25,597 (17%) patients had no surgery. There was no significant difference in stage of presentation between the wealthiest and poorest MHI quartiles, with approximately 35% of patients in each quartile presenting with T1aN0M0 disease and 17% of patients presenting with metastatic disease. Despite this, 18% of patients in the wealthiest quartile underwent partial nephrectomy compared to 14% of patients in the poorest quartile. Although the percentage of patients undergoing partial nephrectomy rose over the timeframe studied in both the wealthiest and poorest quartiles, the rate of rise was highest in the wealthier group. Those in the poorest quartile were 0.10 times more likely to die of all causes (95% CI: 1.09-1.11, P<0.001) and 0.09 times more likely to die of kidney cancer (95% CI: 1.05-1.10, P<0.001) than those in the wealthiest quartile over the timeframe studied.

CONCLUSIONS

Despite presenting with similar stage, patients with lower MHI less commonly undergo partial nephrectomy and are more likely to die of kidney cancer than those in the highest MHIs.

Unilateral Partial Nephrectomy with Warm Ischemia Results in Acute Hypoxia Inducible Factor 1-Alpha (HIF-1α) and Toll-Like Receptor 4 (TLR4) Overexpression in a Porcine Model

Purpose

Ischemia/reperfusion (I/R) during partial nephrectomy (PN) contributes to acute kidney injury (AKI), which is inaccurately assessed using existent clinical markers of renal function. We evaluated I/R-related changes in expression in hypoxia inducible factor 1α (HIF-1α) and toll-like receptor 4 (TLR4), within kidney tissue and peripheral blood leukocytes (PBL) in a porcine model of PN.

Materials and Methods

Three adult pigs each underwent unilateral renal hilar cross clamping for 180 min followed by a 15 min reperfusion. The contralateral kidney served as control. Biopsies of clamped kidneys were obtained at baseline (time 0), every 60 min during the hypoxic phase, and post-reperfusion. Control kidneys were biopsied once at 180 min. Peripheral blood was sampled at time 0, every 30 min during the hypoxic phase, and post-reperfusion. HIF-1α and TLR4 expression in kidney tissue and PBL were analyzed by Western blotting. I/R-related histological changes were assessed.

Results

Expression of HIF-1α in clamped kidneys and PBL was below detection level at baseline, rising to detectable levels after 60 min of hypoxia, and continuing to rise throughout the hypoxic and reperfusion phases. Expression of TLR-4 in clamped kidneys followed a similar trend with initial detection after 30–60 min of hypoxia. Control kidneys exhibited no change in HIF-1α or TLR-4 expression. I/R-related histologic changes were minimal, primarily mild tubular dilatation.

Conclusions

In a porcine model of PN, HIF-1α and TLR4 exhibited robust, I/R-related increases in expression in kidney tissue and PBL. Further studies investigating these molecules as potential markers of AKI are warranted.

Early impact of robot-assisted partial nephrectomy on renal function as assessed by renal scintigraphy

To measure the early impact of robot-assisted partial nephrectomy (RAPN) on renal function as assessed by renal scan (Tc 99m-DTPA), addressing the issue of risk factors for ischemic damage to the kidney. All patients undergoing RAPN for cT1 renal masses between June 2013 and May 2014 were included in this prospective study. Renal function as expressed by glomerular filtration rate (GFR) was assessed by Technetium 99m-diethylenetriaminepentaacetic acid (Tc 99m-DTPA) renal scan preoperatively and postoperatively at 1 month in every patient. A multivariable analysis was used for the determination of independent factors predictive of GFR decrease of the operated kidney. Overall, 32 patients underwent RAPN in the time interval. Median tumor size, blood loss, and ischemia time were 4 cm, 200 mL, and 24 min, respectively. Two grade III complications occurred (postoperative bleeding in the renal fossa, urinoma). The GFR of the operated kidney decreased significantly from 51.7 ± 15.1 mL/min per 1.73 m(2) preoperatively to 40, 12 ± 12.4 mL/min per 1.73 m(2) 1 month postoperatively (p = 0.001) with a decrease of 22.4 %. On multivariable analysis, only tumor size (p = 0.05) was a predictor of GFR decrease of the operated kidney. Robotic-assisted partial nephrectomy had a detectable impact on early renal function in a series of relatively large tumors and prevailing intermediate nephrometric risk. A mean decrease of 22 % of GFR as assessed by renal scan in the operated kidney was found at 1 month postoperatively. In multivariable analysis, tumor size only was a significant predictor of renal function loss.