Tumor Complexity Predicts Malignant Disease for Small Renal Masses

Tumor morphology evaluation using 3D-morphometric features of renal masses

OBJECTIVE

To assess the correlation between the general (gender, age, and maximum tumor size) and 3D morphotopometric features of the renal tumor node, following the MSCT data post-processing, and the tumor histological structure; to propose an equation allowing for kidney malignancy assessment based on general and morphometric features.

MATERIALS AND METHODS

In total, 304 patients with unilateral solitary renal neoplasms underwent laparoscopic (retroperitoneoscopic) or robotic partial or radical nephrectomy. Before the procedure, kidney contrast-enhanced MSCT followed by the tumor 3D-modeling was performed. 3D model of the kidney tumor, and its morphotopometric features, and histological structure were analyzed. The morphotopometric ones include the side of the lesion, location by segments, the surface where the tumor, the depth of the tumor invasion into the kidney, and the shape of tumor.

RESULTS

Out of 304 patients, 254 (83.6%) had malignant kidney tumors and 50 (16.4%) benign kidney tumors. In total, 231 patients, out of 254 (90.9%) were assessed for the degree of malignant tumor differentiation. Malignant tumors were more frequent in men than in women (p < 0.001). Mushroom-shaped tumors were the most common shapes among benign renal masses (35.2%). The most common malignant kidney tumors had spherical with a partially uneven surface (27.6%), multinodular (tuberous (27.2%)), and spherical with a conical base (24.8%) shapes. Logistic regression model enabled the development of prognostic equation for tumor malignancy prediction ("low" or "high"). The univariate analysis revealed the correlation only between high differentiation (G1) and a spherical tumor with a conical base (p = 0.029).

CONCLUSION

The resulting logistic model, based on the analysis of such predictors as gender and form of kidney lesions, demonstrated a large share (87.6%) of correct predictions of the kidney tumor malignancy.

Assessing RNA-Seq Workflow Methodologies Using Shannon Entropy

RNA-seq faces persistent challenges due to the ongoing, expanding array of data processing workflows, none of which have yet achieved standardization to date. It is imperative to determine which method most effectively preserves biological facts. Here, we used Shannon entropy as a tool for depicting the biological status of a system. Thus, we assessed the measurement of Shannon entropy by several RNA-seq workflow approaches, such as DESeq2 and edgeR, but also by combining nine normalization methods with log2 fold change on paired samples of TCGA RNA-seq representing datasets of 515 patients and spanning 12 different cancer types with 5-year overall survival rates ranging from 20% to 98%. Our analysis revealed that TPM, RLE, and TMM normalization, coupled with a threshold of log2 fold change ≥1, for identifying differentially expressed genes, yielded the best results. We propose that Shannon entropy can serve as an objective metric for refining the optimization of RNA-seq workflows and mRNA sequencing technologies.

Associations between R.E.N.A.L. nephrometry score and survival outcomes in renal tumours

OBJECTIVE

The radius-exophytic/endophytic-nearness-anterior/posterior-location nephrometry score could be used to predict surgical outcomes and renal tumour aggressiveness. We aimed to analyse its associations with survival outcomes.

METHODS

We included 1368 patients with sporadic, unilateral and non-metastatic renal tumours who received curative nephrectomy in Zhongshan Hospital from January 2009 to September 2019. Radius-exophytic/endophytic-nearness-anterior/posterior-location nephrometry scores were assigned by three urologists based on preoperative CT/MRI scans. Correlations between parameters or sum of radius-exophytic/endophytic-nearness-anterior/posterior-location nephrometry scores, overall survival and recurrence-free survival were analysed by Kaplan-Meier analyses and the multivariate Cox regression model. We further compared survival outcomes between patients who received partial nephrectomy and patients who received radical nephrectomy.

RESULTS

We observed statistically significant associations between all components of radius-exophytic/endophytic-nearness-anterior/posterior-location nephrometry scores and oncologic outcomes, including R (radius) (overall survival, P < 0.001; recurrence-free survival , P < 0.001), E (exophytic/endophytic) (overall survival, P = 0.003; recurrence-free survival, P < 0.001), N (nearness) (overall survival, P = 0.063; recurrence-free survival, P < 0.001), A (anterior/posterior) (overall survival, P < 0.001; recurrence-free survival, P = 0.005), L (location) (overall survival, P = 0.008; recurrence-free survival, P < 0.001) and suffix 'h' (overall survival, P = 0.237; recurrence-free survival, P = 0.034). Kaplan-Meier curves of overall survival and recurrence-free survival rates were significantly different when stratified by radius-exophytic/endophytic-nearness-anterior/posterior-location nephrometry score complexity group (overall survival, P < 0.001; recurrence-free survival, P < 0.001). After adjusting for tumour stage and grade, radius-exophytic/endophytic-nearness-anterior/posterior-location nephrometry score as continuous variables was an adverse independent risk factor for survival outcomes [P = 0.027, hazard ratio (95% confidence interval) = 1.151 (1.016-1.303)] and recurrence-free survival [P < 0.001, hazard ratio (95% confidence interval) = 1.299 (1.125-1.501)]. For tumours with radius-exophytic/endophytic-nearness-anterior/posterior-location nephrometry scores of 4 and 5, partial nephrectomy showed a survival benefit than radical nephrectomy.

CONCLUSION

Both components and complexity groups of the radius-exophytic/endophytic-nearness-anterior/posterior-location nephrometry score are associated with survival outcomes in renal tumour patients.

Comparison of aggressiveness in central versus peripheral T1a clear-cell renal cell carcinoma

PURPOSE

This study aimed to estimate the difference between peripheral and central small renal lesions in terms of their oncologic potential.

METHODS

Cross-sectional retrospective analysis of patients with small renal masses (T1a) who underwent surgical treatment between January 2008 and July 2019 at the affiliated hospital. Only patients with ccRCC pathology were included. Cases were divided into 2 groups depending on tumor location (central or peripheral) based on the R.E.N.A.L and local nephrometry scoring. Presence of nodal involvement, distant metastases, ISUP grade and endophytic growth were defined as aggressiveness predictors. Statistical analyses was performed using a standard statistical software (IBM SPPS Statistics Ver. 22), with P < 0.05 considered statistically significant. Associations between tumor location and Fuhrman grade, exo-/endophytic growth, TNM classification, and type of operation were tested using the Pearson χ² test and 1-way ANOVA test.

RESULTS

Patients with centrally located tumors had a higher incidence of clinical and pathological lymph node involvement (P = 0.02, χ2 = 5.1). Patients in both groups had an equal number of distant metastases at the time of diagnosis (P = 0.3, χ2 = 0.8). The operation time was significantly longer in patients with central lesions, which obviously showed higher tumor complexity in this group (P < 0.005). Pathological evaluation revealed differences between ISUP grades in both groups (P < 0.005, χ2 = 29.9). Central masses were characterized by higher aggressiveness, indicating a worse prognosis. Furthermore, the cases in the first group were more often endophytic (P = 0.03, χ2 = 0.9). Nevertheless, this did not affect the surgical strategy in most cases with a tendency toward partial nephrectomy. Eventually, organ-sparing treatment was preferable in both groups (P = 0.13, χ2 = 2.29).

CONCLUSION

Centrally located kidney cancer has showed in present study a higher incidence of high ISUP grade, regional nodal involvement and endophytic growth type. Endophytic growth type was associated with worse ISUP grading. Distribution of ISUP grade was not age depended, thus showing no difference by this criterion, when comparing different age groups. Higher ISUP grade was strongly associated with presence of distant metastases in T1a kidney tumors. Further analysis is needed to investigate aggressiveness of centrally located T1a RCC, as it may influence current conservative management options.

Pathological diagnostic nomograms for predicting malignant histology and unfavorable pathology in patients with endophytic renal tumor

Purpose

To develop and validate nomograms for pre-treatment prediction of malignant histology (MH) and unfavorable pathology (UP) in patients with endophytic renal tumors (ERTs).

Methods

We retrospectively reviewed the clinical information of 3245 patients with ERTs accepted surgical treatment in our center. Eventually, 333 eligible patients were included and randomly enrolled into training and testing sets in a ratio of 7:3. We performed univariable and multivariable logistic regression analyses to determine the independent risk factors of MH and UP in the training set and developed the pathological diagnostic models of MH and UP. The optimal model was used to construct a nomogram for MH and UP. The area under the receiver operating characteristics (ROC) curves (AUC), calibration curves and decision curve analyses (DCA) were used to evaluate the predictive performance of models.

Results

Overall, 172 patients with MH and 50 patients with UP were enrolled in the training set; and 74 patients with MH and 21 patients with UP were enrolled in the validation set. Sex, neutrophil-to-lymphocyte ratio (NLR), R score, N score and R.E.N.A.L. score were the independent predictors of MH; and BMI, NLR, tumor size and R score were the independent predictors of UP. Single-variable and multiple-variable models were constructed based on these independent predictors. Among these predictive models, the malignant histology-risk nomogram consisted of sex, NLR, R score and N score and the unfavorable pathology-risk nomogram consisted of BMI, NLR and R score performed an optimal predictive performance, which reflected in the highest AUC (0.842 and 0.808, respectively), the favorable calibration curves and the best clinical net benefit. In addition, if demographic characteristics and laboratory tests were excluded from the nomograms, only the components of the R.E.N.A.L. Nephrometry Score system were included to predict MH and UP, the AUC decreased to 0.781 and 0.660, respectively (P=0.001 and 0.013, respectively).

Conclusion

In our study, the pathological diagnostic models for predicting malignant and aggressive histological features for patients with ERTs showed outstanding predictive performance and convenience. The use of the models can greatly assist urologists in individualizing the management of their patients.

Partial Nephrectomy Versus Radical Nephrectomy for Endophytic Renal Tumors: Comparison of Operative, Functional, and Oncological Outcomes by Propensity Score Matching Analysis

Purpose

The study aimed to compare operative, functional, and oncological outcomes between partial nephrectomy (PN) and radical nephrectomy (RN) for entophytic renal tumors (ERTs) by propensity score matching (PSM) analysis.

Methods

A total of 228 patients with ERTs who underwent PN or RN between August 2014 and December 2021 were assessed. A PSM in a 1:1 ratio was conducted to balance the differences between groups. Perioperative characteristics, renal functional, and oncological outcomes were compared between groups. Univariate and multivariate logistic and Cox proportional hazard regression analyses were used to determine the predictors of functional and survival outcomes.

Results

After PSM, 136 cases were matched to the PN group (n = 68) and the RN group (n = 68). Patients who underwent RN had shorter OT, less EBL, and lower high-grade complications (all p <0.05) relative to those who underwent PN. However, better perseveration of renal function was observed in the PN group, which was reflected in 48-h postoperative AKI (44.1% vs. 70.6%, p = 0.002), 1-year postoperative 90% eGFR preservation (45.6% vs. 22.1%, p = 0.004), and new-onset CKD Stage ≥III at last follow-up (2.9% vs. 29.4%, p <0.001). RN was the independent factor of short-term (OR, 2.812; 95% CI, 1.369–5.778; p = 0.005) and long-term renal function decline (OR, 10.242; 95% CI, 2.175–48.240; p = 0.003). Furthermore, PN resulted in a better OS and similar PFS and CSS as compared to RN (p = 0.042, 0.15, and 0.21, respectively). RN (OR, 7.361; 95% CI, 1.143–47.423; p = 0.036) and pT3 stage (OR, 4.241; 95% CI, 1.079–16.664; p = 0.039) were independent predictors of overall mortality.

Conclusion

Among patients with ERTs, although the PN group showed a higher incidence of high-grade complications than RN, when technically feasible and with experienced surgeons, PN is recommended for better preservation of renal function, longer OS, and similar oncological outcomes.

Computed tomography features predicting aggressiveness of malignant parenchymal renal tumors suitable for partial nephrectomy

The aim of this study was to identify and standardize computed tomography (CT) features having a potential role in predicting aggressiveness of malignant parenchymal renal tumors suitable for partial nephrectomy (PN). We performed a non-systematic review of the recent literature to evaluate the potential impact of CT variables proposed by the Society of Abdominal Radiology Disease-Focused Panel on Renal Cell Carcinoma in predicting aggressiveness of newly diagnosed malignant parenchymal renal tumors. The analyzed variables were clinical tumor size, tumor growth rate, enhancement characteristics, amount of cystic component, polar and capsular location, tumor margins and distance between tumor and renal sinus. Unfavorable behavior was defined as: 1) renal cell carcinoma (RCC) with stage ≥pT3; 2) nuclear grade 3 or 4; 3) presence of sarcomatoid de-differentiation; or 4) non-clear cell subtypes with unfavorable prognosis (type 2 papillary RCC, collecting duct or renal medullary carcinoma, unclassified RCC). Beyond clinical tumor size, tumor growth rate, enhancement characteristics, amount of cystic component, tumor margins and distance between tumor and renal sinus are highly relevant features predicting an unfavorable behavior. Moreover, several studies supported the role of necrosis as preoperative predictor of tumor aggressiveness. Peritumoral and intratumoral vasculature as well as capsule status are emerging variables that need to be further evaluated. Tumor size, enhancement characteristics, tumor margins and distance to the renal sinus are highly relevant CT features predicting biological aggressiveness of malignant parenchymal renal tumors. Combination of these parameters might be useful to generate tools to predict the unfavorable behavior of renal tumors suitable for PN.

Nephron-Sparing Surgery for Adult Xp11.2 Translocation Renal Cell Carcinoma at Clinical T1 Stage: A Multicenter Study in China

Purpose

To evaluate the oncologic efficacy and feasibility of nephron-sparing surgery (NSS) in adult Xp11.2 translocation renal cell carcinoma (RCC).

Patients and Methods

Seventy patients with Xp11.2 translocation RCC and 273 with conventional RCC from five institutions in Nanjing were retrospectively studied. All patients were older than 18 years and were categorized into clinical T1 (cT1) stage using preoperative imaging. Using the preoperative imaging and electronic medical records, anatomical and pathological features were collected and analyzed.

Results

Among patients with Xp11.2 translocation RCC, 18/36 (50.0%) with cT1a and 12/34 (35.3%) with cT1b tumors underwent NSS. The respective proportions in the conventional RCC group were 121/145 (83.4%) and 93/128 (72.7%). Among cT1a tumors, the Xp11.2 translocation RCCs tended to be adjacent to the collecting system, sinus, and axial renal midline compared with conventional RCCs. Patients with Xp11.2 translocation RCCs who underwent NSS had comparable progression-free survival (PFS) and overall survival to radical nephrectomy (RN) patients (P > 0.05). Among cT1b tumors, surgical margin positivity and pelvicalyceal, vascular, and region lymphatic involvement were more likely to occur in the Xp11.2 translocation RCCs (P < 0.05). Patients with Xp11.2 translocation RCC who underwent RN had a more favorable PFS than those who underwent NSS (P = 0.048). However, multivariate analysis of PFS did not identify surgical method as a risk factor (P = 0.089).

Conclusions

Among adults with Xp11.2 translocation RCC, NSS can be an alternative for patients with cT1a tumor but should be performed with more deliberation in patients with cT1b tumors.

Electronic supplementary material

The online version of this article (10.1245/s10434-020-08813-y) contains supplementary material, which is available to authorized users.

Analyzing National Incidences and Predictors of Open Conversion During Minimally Invasive Partial Nephrectomy for cT1 Renal Masses

Objectives: To analyze predictors of open conversion during minimally invasive partial nephrectomy (MIPN) for cT1 renal masses. Methods: The National Cancer Database (NCDB) was investigated for kidney cancer patients who underwent partial nephrectomy (PN) between 2010 and 2015. Patients who underwent MIPN were stratified into converted and nonconverted groups. Sociodemographics, facility characteristics, and surgical outcomes were compared between the two groups, and multivariate logistic regression model was fitted to identify independent predictors of open conversion. Results: In total, 54,246 patients underwent PN for kidney cancer during the 6-year period. Of those, 18,994 (35%) were open partial nephrectomies (OPNs) and 35,252 (64%) were MIPN. Overall, 1010 (2.87%) of MIPNs were converted to OPN. There was an increasing utilization of MIPN from 50.35% in 2010 to 74.73% in 2015. Patients who had open conversion had more 30-day readmissions (5.95% vs 3.31%, p < 0.01). On multivariate analysis; high-volume facility (>30 MIPNs/year), year of surgery (2015 vs 2010), and robotic approach predicted a lower likelihood of conversion (odds ratio [OR] 0.52, confidence interval [CI] 0.44-0.62; OR 0.59, CI 0.47-0.73; and OR 0.31, CI 0.27-0.35; respectively, p < 0.001 for all). Conversely, Medicaid (vs private insurance; OR 1.75, CI 1.39-2.19, p < 0.001) and male sex (OR 1.26, CI 1.11-1.44, p < 0.001) were independent predictors of conversion. Conclusions: Open conversion in MIPN occurred in 2.87% of cases. There was an increasing utilization of MIPN associated with decreased conversion rates. Higher volume hospitals and progressing year of surgery were associated with less likelihood of conversion.

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

CONTEXT

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

OBJECTIVE

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

EVIDENCE ACQUISITION

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

EVIDENCE SYNTHESIS

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

CONCLUSIONS

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

PATIENT SUMMARY

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

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

RATIONALE AND OBJECTIVES

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

Classification tree for the prediction of malignant disease and the prediction of non-diagnostic biopsies in patients with small renal masses

INTRODUCTION

Preoperative prediction of benign vs. malignant small renal masses (SRMs) remains a challenge. This study: 1) validates our previously published classification tree (CT) with an external cohort; 2) creates a new CT with the combined cohort; and 3) evaluates the RENAL and PADUA scoring systems for prediction of malignancy.

METHODS

This study includes a total of 818 patients with renal masses; 395 underwent surgical resection and 423 underwent biopsy. A CT to predict benign disease was developed using patient and tumour characteristics from the 709 eligible participants. Our CT is based on four parameters: tumour volume, symptoms, gender, and symptomatology. CART modelling was also used to determine if RENAL and PADUA scoring could predict malignancy.

RESULTS

When externally validated with the surgical cohort, the predictive accuracy of the old CT dropped. However, by combining the cohorts and creating a new CT, the predictive accuracy increased from 74% to 87% (95% confidence interval 0.84-0.89). RENAL and PADUA score alone were not predictive of malignancy. One limitation was the lack of available histological data from the biopsy series.

CONCLUSIONS

The validated old CT and new combined-cohort CT have a predictive value greater than currently published nomograms and single-biopsy cohorts. Overall, RENAL and PADUA scores were not able to predict malignancy.

The Probability of Aggressive Versus Indolent Histology Based on Renal Tumor Size: Implications for Surveillance and Treatment

BACKGROUND

While the probability of malignant versus benign histology based on renal tumor size has been described, this alone does not sufficiently inform decision-making in the modern era since indolent malignant tumors can be managed with active surveillance.

OBJECTIVE

To characterize the probability of aggressive versus indolent histology based on radiographic tumor size.

DESIGN, SETTING, AND PARTICIPANTS

We evaluated patients who underwent radical or partial nephrectomy at Mayo Clinic for a pT1-2, pNx/0, M0 solid renal tumor between 1990 and 2010. Pathology was reviewed by one genitourinary pathologist. High-grade clear-cell renal cell carcinoma (RCC), high-grade papillary RCC, collecting duct RCC, translocation-associated RCC, hereditary leiomyomatosis RCC, unclassified RCC, and malignant non-RCC tumors were all considered aggressive, as well as any tumors demonstrating coagulative necrosis (except low-grade papillary RCC) or sarcomatoid differentiation. The remaining benign and malignant tumors were considered indolent.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Cancer-specific survival (CSS) was estimated using the Kaplan-Meier method. Logistic regression models were used to estimate the probability of malignant and aggressive histology based on tumor size. Sex-stratified analyses were also performed.

RESULTS AND LIMITATIONS

Of the 2650 patients included, there were 1860 patients with indolent tumors (300 benign; 1560 malignant) and 790 with aggressive tumors. The 10-yr CSS was 96% for indolent malignant tumors and 81% for aggressive malignant tumors. The predicted percentages of any malignant histology as well as aggressive histology increased with tumor size. Specifically, 2cm, 3cm, and 4cm tumors have an estimated 84%, 87%, and 88% likelihood of malignancy, respectively, and an 18%, 24%, and 29% likelihood of aggressive histology, respectively. For any given tumor size, men had a greater chance of aggressive histology than women. Potential limitations of this observational surgical cohort include selection bias.

CONCLUSIONS

We present tumor size-based estimates of the probability of aggressive histology for renal masses. This information should be useful for initial patient counseling and management.

PATIENT SUMMARY

Active surveillance is an option for kidney masses, even if they are malignant. Beyond knowing whether the mass is benign or cancer, it is important to know whether or not it is an aggressive tumor. This study presents tumor size-specific and sex-specific estimates of the probability of cancer overall and aggressive cancer among patients with a kidney mass in order to aid with initial decision-making.

Practical Applications of Immunohistochemistry in the Diagnosis of Genitourinary Tumors

Context.—

Pathologic diagnosis of tumors in the genitourinary system can be challenging based on morphology alone, particularly when diagnostic material is limited, such as in core biopsies. Immunohistochemical stain can be a useful tool to aid in the diagnosis.

Objective.—

To provide an update on practical applications and interpretation of immunohistochemical stains in the diagnosis of tumors in prostate, kidney, bladder, and testis. We particularly focus on difficult differential diagnoses, providing our insights in frequently encountered challenging situations. Commonly used immunohistochemical panels are discussed.

Data Sources.—

Review of literature and our own experience.

Conclusion.—

Immunohistochemical stain is a valuable tool in the diagnosis of genitourinary tumors when appropriately used.

Active Surveillance for Small Renal Masses: When Less is More

CONTEXT

A marked increase in incidentally detected small renal masses (SRMs) has occurred over the past decade. Active surveillance (AS) has emerged as an initial management option for these patients.

OBJECTIVE

(1) To determine selection criteria, assess appropriate imaging modalities and surveillance frequencies, and define triggers for delayed intervention (DI) for patients on AS. (2) To describe oncologic outcomes for patients on AS protocols.

EVIDENCE ACQUISITION

The PubMed database was queried for English language articles using the keywords "surveillance" and "renal mass" or "renal cell carcinoma" or "kidney cancer." The level of evidence, sample size, study design, and relevance to the review were considered as inclusion criteria.

EVIDENCE SYNTHESIS

A total of 69 manuscripts were included in the review. Selection criteria at initial evaluation for patients interested in AS include patient-related factors (eg, age, baseline renal function, other comorbidities), tumor-related factors (size, complexity, history of growth, possible renal mass biopsy), and patient preferences (illness uncertainty, quality of life). Cross-sectional imaging is the preferred initial imaging modality. Surveillance imaging should be performed at frequent intervals (3-4 mo) up front; intervals can be reduced over time if favorable growth kinetics are demonstrated. Delayed intervention (DI) should be considered for rapid tumor growth (eg,>0.5cm/yr), an increase in maximum tumor diameter >3-4cm, malignant renal mass biopsy results, development of symptoms, or patient preferences. Oncologic outcomes in well-controlled studies demonstrate a metastatic rate of 1-2%. Most patients who undergo DI remain eligible for nephron-sparing approaches; oncologic outcomes are not compromised by DI strategies.

CONCLUSIONS

A period of initial AS is safe for most patients with SRMs. Management decisions should focus on a thorough assessment of risk-benefit trade-offs, judiciously integrating patient-related factors, tumor-related factors, and patient preferences.

PATIENT SUMMARY

A period of initial active surveillance for kidney masses of ≤4cm in diameter is safe in most patients. Frequent imaging and follow-up are necessary to determine if the tumor grows. If delayed intervention becomes necessary, cancer outcomes are not compromised by the initial choice of active surveillance when patients adhere to close follow-up regimens.

When Partial Nephrectomy is Unsuccessful: Understanding the Reasons for Conversion from Robotic Partial to Radical Nephrectomy at a Tertiary Referral Center

PURPOSE

We sought to identify the preoperative factors associated with conversion from robotic partial nephrectomy to radical nephrectomy. We report the incidence of this event.

MATERIALS AND METHODS

Using our institutional review board approved database, we abstracted data on 1,023 robotic partial nephrectomies performed at our center between 2010 and 2015. Standard and converted cases were compared in terms of patients and tumor characteristics, and perioperative, functional and oncologic outcomes. Logistic regression analysis was done to identify predictors of radical conversion.

RESULTS

The overall conversion rate was 3.1% (32 of 1,023 cases). The most common reasons for conversion were tumor involvement of hilar structures (8 cases or 25%), failure to achieve negative margins on frozen section (7 or 21.8%), suspicion of advanced disease (5 or 15.6%) and failure to progress (5 or 15.6%). Patients requiring conversion were older and had a higher Charlson score (both p <0.01), including an increased prevalence of chronic kidney disease (p = 0.02). Increasing tumor size (5 vs 3.1 cm, p <0.01) and R.E.N.A.L. (radius, exophytic/endophytic properties, nearness of tumor to collecting system or sinus, anterior/posterior, location relative to polar lines and hilar location) score (9 vs 8, p <0.01) were also associated with an increased risk of conversion. Worse baseline renal function (OR 0.98, 95% CI 0.96-0.99, p = 0.04), large tumor size (OR 1.44, 95% CI 1.22-1.7, p <0.01) and increasing R.E.N.A.L. score (p = 0.02) were independent predictors of conversion. Compared to converted cases, at latest followup standard robotic partial nephrectomy cases had similar short-term oncologic outcomes but better renal functional preservation (p <0.01).

CONCLUSIONS

At a high volume center the rate of robotic partial nephrectomy conversion to radical nephrectomy was 3.1%, including 2.2% of preoperatively anticipated nephrectomy cases. Increasing tumor size and complexity, and poor preoperative renal function are the main predictors of conversion.

Evaluation of the Clinical Use of Robot-Assisted Retroperitoneal Laparoscopy and Preoperative RENAL Scoring for Nephron Sparing Surgery in Renal Tumor Patients

The present study aims to compare the operative outcomes following the use of robot-assisted retroperitoneal partial nephrectomy (RARPN) with radius, exophytic/endophytic, nearness to sinus, anterior/posterior, and location (RENAL) scoring or laparoscopic retroperitoneal partial nephrectomy (LRPN) for the treatment of renal tumors. Eighty-three nephron-sparing surgery (NSS) procedures performed between January 2013 and December 2015 were reviewed. The study set consisted of 26 robot-assisted retroperitoneal laparoscopes, of which 3 were high risk (RENAL score ≥10), 11 were medium risk (RENAL score ≥7 < 9), and 12 were low risk (RENAL score <7) and 57 laparoscopic retroperitoneal partial nephrectomy procedures (7 high, 22 medium, and 28 low risk). All surgeries were successful in the absence of conversion or transfusion. Operative times were 96.0 ± 16.9 and 110.0 ± 19.4 min for RARPN and LRPN, respectively (P < 0.05). Warm ischemia times (WITs) were 17.6 ± 3.1 and 22.8 ± 3.5 min, respectively (P < 0.05). Estimated blood losses (EBLs) were 45 ± 15 and 97 ± 25 mL, respectively (P < 0.05). No statistical significance was found in duration of drainage, intestinal recovery time, hospital stay, serum creatinine, and perioperative complications (P > 0.05). RARPN affords significant advantages in outcomes of WIT, EBL, and recovery time over conventional LRPN owing to an increased accuracy in excision and suturing. Patients bearing high-risk renal tumors (RENAL score ≥10) are suitable candidates for RARPN.

Prediction of renal mass aggressiveness using clinical and radiographic features: a global, multicentre prospective study

OBJECTIVE

To examine the ability of preoperative clinical characteristics to predict histological features of renal masses (RMs).

PATIENTS AND METHODS

Data from consecutive patients with clinical stage I RMs treated surgically between 2010 and 2011 in the Clinical Research Office of Endourology Society (CROES) Renal Mass Registry were collected. Based on surgical histology, tumours were categorised as benign, low- or high-aggressiveness cancer. Multivariate logistic regression was used to estimate the probability of the histological group by clinical and radiographic features in the entire cohort and a subcohort of cT1a tumours. The performance of the models was studied by calibration, Nagelkerke's R(2) , and discrimination (area under the receiver operating characteristic curve).

RESULTS

The study cohort included 2 224 patients with a clinical stage I RM, of which 1 367 (61%) were cT1a. Benign lesions were found in 369 (16.6%), low-aggressiveness tumours in 1 156 (52%) and high-aggressiveness tumours in 699 (31.4%). Male gender, smoking history, increased tumour size, and lower exophytic rate were associated with malignancy and high-aggressiveness features (all P < 0.05). Models developed based on these characteristics had the ability to discriminate benign from malignant (bootstrap corrected c-index of 0.64) and high-aggressiveness tumours from benign and low-aggressiveness tumours (bootstrap corrected c-index of 0.66). Similar results were achieved in the cT1a subgroup. The c-index of tumour diameter as a single predictor of malignancy and high-aggressiveness tumours in the entire cohort was 0.6 and 0.63, respectively.

CONCLUSION

Although older age, male gender, smoking history, increased tumour diameter, and reduced exophytic rate are associated with malignancy and high aggressiveness of clinical stage I RMs, models incorporating these characteristics have modest discriminating power, being only slightly better than the predictive ability of tumour size alone.

Comparison of computed tomography findings between renal oncocytomas and chromophobe renal cell carcinomas

Purpose

To investigate and distinguish the computed tomography (CT) characteristics of chromophobe renal cell carcinoma (chRCC) and renal oncocytoma.

Materials and Methods

Fifty-one patients with renal oncocytoma and 120 patients with chRCC, diagnosed by surgery between November 2005 and June 2015, were studied retrospectively. Two observers, who were urologists and unaware of the pathological results, reviewed the preoperative CT images. The tumors were evaluated for size, laterality, tumor type (ball or bean pattern), central stellate scar, segmental enhancement inversion, and angular interface pattern and tumor complexity. To accurately analyze the mass-enhancing pattern of renal mass, we measured Hounsfield units (HUs) in each phase and analyzed the mean, maximum, and minimum HU values and standard deviations.

Results

There were 51 renal oncocytomas and 120 chRCCs in the study cohort. No differences in clinical and demographic characteristics were observed between the two groups. A central stellate scar and segmental enhancement inversion were more likely in oncocytomas. However, there were no differences in ball-/bean-type categorization, enhancement pattern, and the shape of the interface between the groups. Higher HU values tended to be present in the corticomedullary and nephrogenic phases in oncocytomas than in chRCC. Receiver-operating characteristic curve analysis showed that the presence of a central stellate scar and higher mean HU values in the nephrogenic phase were highly predictive of renal oncocytoma (area under the curve=0.817, p<0.001).

Conclusions

The appearance of a central stellate scar and higher mean HU values in the nephrogenic phase could be useful to distinguish renal oncocytomas from chRCCs.

R.E.N.A.L. nephrometry score predicts postoperative recurrence of localized renal cell carcinoma treated by radical nephrectomy

Background

We investigated the association between the R.E.N.A.L. nephrometry score (RNS) and the postoperative recurrence of localized renal cell carcinoma (RCC).

Methods

We retrospectively analyzed a database comprising 91 patients with non-small localized RCC (pT1b–T2b) treated by radical nephrectomy at our hospital from January 2002 to March 2010. RNS was scored based on imaging findings at diagnosis. The Cox proportional hazards model was used to predict recurrence-free survival (RFS) and to calculate hazard ratio (HR).

Results

The median age at operation was 63 years (range, 30–85 years). Postoperative recurrence occurred in 19 patients (21 %). Median RNS sum was 9 (range, 5–11). High RNS sum (10–12) was significantly associated with RFS (P = 0.0012). Multivariate analysis revealed that high RNS sum [HR, 9.05; 95 % confidence interval (CI), 2.11–63.9; P = 0.0019] were significantly associated with RFS. Regarding each component of RNS, only the L component, which referred to tumor location relative to the polar line, was associated with RFS (HR, 15.0; 95 % CI, 2.68–396; P = 0.0006).

Conclusions

RNS was associated with RFS in cases of non-small localized RCC (pT1b–2b), thus supporting its utility as a prognostic factor.

A Literature Review of Renal Surgical Anatomy and Surgical Strategies for Partial Nephrectomy

CONTEXT

A detailed understanding of renal surgical anatomy is necessary to optimize preoperative planning and operative technique and provide a basis for improved outcomes.

OBJECTIVE

To evaluate the literature regarding pertinent surgical anatomy of the kidney and related structures, nephrometry scoring systems, and current surgical strategies for partial nephrectomy (PN).

EVIDENCE ACQUISITION

A literature review was conducted.

EVIDENCE SYNTHESIS

Surgical renal anatomy fundamentally impacts PN surgery. The renal artery divides into anterior and posterior divisions, from which approximately five segmental terminal arteries originate. The renal veins are not terminal. Variations in the vascular and lymphatic channels are common; thus, concurrent lymphadenectomy is not routinely indicated during PN for cT1 renal masses in the setting of clinically negative lymph nodes. Renal-protocol contrast-enhanced computed tomography or magnetic resonance imaging is used for standard imaging. Anatomy-based nephrometry scoring systems allow standardized academic reporting of tumor characteristics and predict PN outcomes (complications, remnant function, possibly histology). Anatomy-based novel surgical approaches may reduce ischemic time during PN; these include early unclamping, segmental clamping, tumor-specific clamping (zero ischemia), and unclamped PN. Cancer cure after PN relies on complete resection, which can be achieved by thin margins. Post-PN renal function is impacted by kidney quality, remnant quantity, and ischemia type and duration.

CONCLUSIONS

Surgical renal anatomy underpins imaging, nephrometry scoring systems, and vascular control techniques that reduce global renal ischemia and may impact post-PN function. A contemporary ideal PN excises the tumor with a thin negative margin, delicately secures the tumor bed to maximize vascularized remnant parenchyma, and minimizes global ischemia to the renal remnant with minimal complications.

PATIENT SUMMARY

In this report we review renal surgical anatomy. Renal mass imaging allows detailed delineation of the anatomy and vasculature and permits nephrometry scoring, and thus precise, patient-specific surgical planning. Novel off-clamp techniques have been developed that may lead to improved outcomes.

Is anatomic complexity associated with renal tumor growth kinetics under active surveillance?

INTRODUCTION

Linear growth rate (LGR) is the most commonly employed trigger for definitive intervention in patients with renal masses managed with an initial period of active surveillance (AS). Using our institutional cohort, we explored the association between tumor anatomic complexity at presentation and LGR in patients managed with AS.

METHODS AND MATERIALS

Enhancing renal masses managed expectantly for at least 6 months were included for analysis. The association between Nephrometry Score and LGR was assessed using generalized estimating equations, adjusting for the age, Charlson score, race, sex, and initial tumor size.

RESULTS

Overall, 346 patients (401 masses) met the inclusion criteria (18% ≥ cT1b), with a median follow-up of 37 months (range: 6-169). Of these, 44% patients showed progression to definitive intervention with a median duration of 27 months (range: 6-130). On comparing patients managed expectantly to those requiring intervention, no difference was seen in median tumor size at presentation (2.2 vs. 2.2 cm), whereas significant differences in median age (74 vs. 65 y, P < 0.001), Charlson comorbidity score (3 vs. 2, P<0.001), and average LGR (0.23 vs. 0.49 cm/y, P < 0.001) were observed between groups. Following adjustment, for each 1-point increase in Nephrometry Score sum, the average tumor LGR increased by 0.037 cm/y (P = 0.002). Of the entire cohort, 6 patients (1.7%) showed progression to metastatic disease.

CONCLUSIONS

The demonstrated association between anatomic tumor complexity at presentation and renal masses of LGR of clinical stage 1 under AS may afford a clinically useful cue to tailor individual patient radiographic surveillance schedules and warrants further evaluation.

Preoperative predictors of malignancy and unfavorable pathology for clinical T1a tumors treated with partial nephrectomy: a multi-institutional analysis

PURPOSE

To determine preoperative predictors associated with renal cell carcinoma (RCC) and unfavorable pathology in small renal masses treated with partial nephrectomy (PN).

MATERIALS AND METHODS

PN records from 5 centers were retrospectively queried for patients with a clinically localized single tumor <4 cm on imaging (clinical T1a). Between 2007 and 2013, 1,009 patients met the inclusion criteria. Unfavorable pathology was defined as any grade III or IV RCC or tumors upstaged to pathologic T3a disease. Logistic regression models were used to determine preoperative characteristics associated with RCC and with unfavorable pathology.

RESULTS

A total of 771 (76.4%) patients were found to have RCC and 198 (19.6%) had unfavorable pathology. On multivariate, bootstrap-adjusted logistic regression analysis, factors associated with the presence of malignancy were imaging tumor size ≥ 3 cm (odds ratio [OR] = 1.46; P = 0.040), male sex (OR = 1.88; P<0.0001), and nephrometry score ≥ 8 (OR = 1.64; P = 0.005). These same factors were independently associated with risk of unfavorable pathology: size ≥ 3 cm (OR = 1.46; P = 0.021), male sex (OR = 2.35; P<0.0001), and nephrometry score ≥ 8 (OR = 1.49; P = 0.015). The c statistic was 0.62 for the predicting malignancy and 0.63 for unfavorable pathology.

CONCLUSIONS

In this multi-institutional cohort, male sex, imaging tumor size ≥ 3 cm, and nephrometry score ≥ 8 were predictors of RCC and adverse pathology following PN. These factors may assist in risk stratification and selective renal mass biopsy before decision making. Further studies are necessary to validate these findings.

High R.E.N.A.L. Nephrometry scores are associated with pathologic upstaging of clinical T1 renal-cell carcinomas in radical nephrectomy specimens: implications for nephron-sparing surgery

BACKGROUND AND PURPOSE

The R.E.N.A.L. Nephrometry Score (RNS) was developed to standardize the reporting of anatomic information of a renal mass. This study aimed to identify the association of preoperative clinical and tumor features assessed by the RNS with pathologic upstaging of clinical T1 renal-cell carcinomas (RCCs) in complete en bloc radical nephrectomy (RN) specimens.

PATIENTS AND METHODS

A review was performed for 65 consecutive patients (2005-2013) who underwent RNs for a unilateral clinical T1N0M0 RCC. The RNS was measured in all patients based on preoperative CT scans. Pathologic review was performed to identify patients with final pathologic upstaging. Associations were assessed with the Fisher exact test, Student t test, and Wilcoxon rank sum test.

RESULTS

Of the 65 patients (41 male, mean age 59 years), 4 (6%) patients were upstaged to pT2 and 16 (25%) were upstaged to pT3a and above in the final histologic evaluation. Upstaged patients were not significantly different from those without in terms of age, sex, race, surgical approach, side of surgery, Fuhrman grade, and histologic cell type. Independent tumor features associated with pathologic upstaging were (R) tumor diameter (P=0.021), and (L) central location within polar lines (P=0.010). Tumors that were upstaged had a higher median total RNS than those without (10 vs 9, P=0.010). Complex tumors, with RNS≥10, were associated with significantly increased risk of upstaging compared with low and intermediate complexity categories (RNS<10) (relative risk=2.56, 95% confidence interval 1.22-5.37, P=0.014).

CONCLUSIONS

A higher RNS was associated with an increased risk of upstaging in clinical T1 cancers, predominantly from perinephric or sinus fat invasion in RN pathologic specimens. This may have implications on the selection of surgical option for the clinical T1 renal mass.

Morphometric scores for renal tumors: what does the radiologist need to know?

Numerous therapeutic options are possible in the treatment of renal carcinomas including radical nephrectomy, partial nephrectomy, cryoablation, radiofrequency, active follow-up and among surgical treatments, different approaches may be used such as laparotomy, laparoscopy, robotic-assisted intervention. The choice between these different procedures is partially based on the anatomic conditions of the tumors. Different anatomic scores determined from cross-sectional imaging have been built to predict the complexity of the surgical procedure. The goals of this article are to review the relevant morphologic pattern for management of patients with renal tumors, to know how to calculate these different scores and to understand the clinical applications of these scores.

RENAL nephrometry score is a predictive factor for the annual growth rate of renal mass

OBJECTIVE

To evaluate the association between the RENAL nephrometry score and annual growth rates of renal masses presumed to be renal cell carcinoma.

METHODS

The current study included 47 renal tumors followed up for at least 12 months, of which 26 tumors were found to be pathologically proven renal cell carcinomas. Annual tumor growth rates were calculated from changes in the maximal diameter on computed tomography, and RENAL nephrometry scores were recorded on initial imaging by two senior urologists. The associations between clinical characteristics including the RENAL nephrometry score and annual growth rates were analyzed using a linear regression model.

RESULTS

The median tumor size at diagnosis was 1.7 cm (range 0.6-5.8). The median nephrometry score at diagnosis was 7 (range 4-10). Overall, the median tumor growth rate was 0.34 cm per year (range -0.19-2.0). Linear regression analysis showed that the annual tumor growth rate was associated with the RENAL nephrometry score (P < 0.0001), but it was independent of the age at diagnosis, sex and initial tumor size. In addition, the correlation between the RENAL nephrometry score and annual growth rate remained significant in the 26 pathologically proven renal cell carcinomas.

CONCLUSIONS

The RENAL nephrometry score is associated with the annual growth rate of renal masses. Our findings further support the association between the RENAL nephrometry score and tumor biology.