Outcome prediction for renal cell carcinoma: evaluation of prognostic factors for tumours divided according to histological subtype

Investigation of clear cell renal cell carcinoma grades using diffusion-relaxation correlation spectroscopic imaging with optimized spatial-spectrum analysis

OBJECTIVES

To differentiate high-grade from low-grade clear cell renal cell carcinoma (ccRCC) using diffusion-relaxation correlation spectroscopic imaging (DR-CSI) spectra in an equal separating analysis.

METHODS

Eighty patients with 86 pathologically confirmed ccRCCs who underwent DR-CSI were enrolled. Two radiologists delineated the region of interest. The spectrum was derived based on DR-CSI and was further segmented into multiple equal subregions from 2*2 to 9*9. The agreement between the 2 radiologists was assessed by the intraclass correlation coefficient (ICC). Logistic regression was used to establish the regression model for differentiation, and 5-fold cross-validation was used to evaluate its accuracy. McNemar's test was used to compare the diagnostic performance between equipartition models and the traditional parameters, including the apparent diffusion coefficient (ADC) and T2 value.

RESULTS

The inter-reader agreement decreased as the divisions in the equipartition model increased (overall ICC ranged from 0.859 to 0.920). The accuracy increased from the 2*2 to 9*9 equipartition model (0.68 for 2*2, 0.69 for 3*3 and 4*4, 0.70 for 5*5, 0.71 for 6*6, 0.78 for 7*7, and 0.75 for 8*8 and 9*9). The equipartition models with divisions >7*7 were significantly better than ADC and T2 (vs ADC: P = .002-.008; vs T2: P = .001-.004).

CONCLUSIONS

The equipartition method has the potential to analyse the DR-CSI spectrum and discriminate between low-grade and high-grade ccRCC.

ADVANCES IN KNOWLEDGE

The evaluation of DR-CSI relies on prior knowledge, and how to assess the spectrum derived from DR-CSI without prior knowledge has not been well studied.

The Effectiveness of Volumetric MRI Histogram Analysis in Renal Cell Carcinoma

RATIONALE AND OBJECTIVES

This study investigated the utility of histogram parameters derived from diffusion-weighted imaging (DWI) for evaluating renal cell carcinoma (RCC) grading prior to surgery.

MATERIALS AND METHODS

This retrospective study included 88 patients who were histopathologically diagnosed with RCC and underwent magnetic resonance imaging (MRI) examinations. The patients were divided into two groups as well-differentiated (Group 1) and poorly differentiated (Group 2). Demographic data, preoperative MRI findings, MRI apparent diffusion coefficient (ADC) histogram analyzes, operation types, postoperative histopathological data and cancer stages of the patients were recorded. The histogram parameters of ADC values, comprising the mean, minimum, maximum, 5th, 10th, 25th, 50th, 75th, 90th, and 95th percentiles, as well as skewness, kurtosis, and variance, were calculated.

RESULTS

The study included 59 males and 29 women with an average age of 56.21 ± 1.33 years. There were 52 patients in Group 1 and 36 patients in Group 2. The ADCmin, ADCmean, ADCmax, 5th, 10th, 25th, 50th, 75th, 90th, and 95th percentiles of ADC values of the poorly differentiated group were all lower than those of the well-differentiated group. ADCmin and the 5th percentile of ADC values, as well as ADCmean and the 10th, 25th, 50th, and 75th percentiles of ADC values, showed a statistically significant difference (p < 0.05). The AUC, sensitivity, and specificity of the ADCmin value were 0.703, 56.3%, and 75.7%, respectively.

CONCLUSION

The present study indicated that histogram parameters generated from DWI were capable of differentiating between high-grade and low-grade RCC.

Role of AI and Radiomic Markers in Early Diagnosis of Renal Cancer and Clinical Outcome Prediction: A Brief Review

Globally, renal cancer (RC) is the 10th most common cancer among men and women. The new era of artificial intelligence (AI) and radiomics have allowed the development of AI-based computer-aided diagnostic/prediction (AI-based CAD/CAP) systems, which have shown promise for the diagnosis of RC (i.e., subtyping, grading, and staging) and prediction of clinical outcomes at an early stage. This will absolutely help reduce diagnosis time, enhance diagnostic abilities, reduce invasiveness, and provide guidance for appropriate management procedures to avoid the burden of unresponsive treatment plans. This survey mainly has three primary aims. The first aim is to highlight the most recent technical diagnostic studies developed in the last decade, with their findings and limitations, that have taken the advantages of AI and radiomic markers derived from either computed tomography (CT) or magnetic resonance (MR) images to develop AI-based CAD systems for accurate diagnosis of renal tumors at an early stage. The second aim is to highlight the few studies that have utilized AI and radiomic markers, with their findings and limitations, to predict patients' clinical outcome/treatment response, including possible recurrence after treatment, overall survival, and progression-free survival in patients with renal tumors. The promising findings of the aforementioned studies motivated us to highlight the optimal AI-based radiomic makers that are correlated with the diagnosis of renal tumors and prediction/assessment of patients' clinical outcomes. Finally, we conclude with a discussion and possible future avenues for improving diagnostic and treatment prediction performance.

Use of Circular RNAs in Diagnosis, Prognosis and Therapeutics of Renal Cell Carcinoma

Renal cell carcinoma is the most common type of kidney cancer, representing 90% of kidney cancer diagnoses, and the deadliest urological cancer. While the incidence and mortality rates by renal cell carcinoma are higher in men compared to women, in both sexes the clinical characteristics are the same, and usually unspecific, thereby hindering and delaying the diagnostic process and increasing the metastatic potential. Regarding treatment, surgical resection remains the main therapeutic strategy. However, even after radical nephrectomy, metastasis may still occur in some patients, with most metastatic renal cell carcinomas being resistant to chemotherapy and radiotherapy. Therefore, the identification of new biomarkers to help clinicians in the early detection, and treatment of renal cell carcinoma is essential. In this review, we describe circRNAs related to renal cell carcinoma processes reported to date and propose the use of some in therapeutic strategies for renal cell carcinoma treatment.

A Comprehensive Computer-Assisted Diagnosis System for Early Assessment of Renal Cancer Tumors

Renal cell carcinoma (RCC) is the most common and a highly aggressive type of malignant renal tumor. In this manuscript, we aim to identify and integrate the optimal discriminating morphological, textural, and functional features that best describe the malignancy status of a given renal tumor. The integrated discriminating features may lead to the development of a novel comprehensive renal cancer computer-assisted diagnosis (RC-CAD) system with the ability to discriminate between benign and malignant renal tumors and specify the malignancy subtypes for optimal medical management. Informed consent was obtained from a total of 140 biopsy-proven patients to participate in the study (male = 72 and female = 68, age range = 15 to 87 years). There were 70 patients who had RCC (40 clear cell RCC (ccRCC), 30 nonclear cell RCC (nccRCC)), while the other 70 had benign angiomyolipoma tumors. Contrast-enhanced computed tomography (CE-CT) images were acquired, and renal tumors were segmented for all patients to allow the extraction of discriminating imaging features. The RC-CAD system incorporates the following major steps: (i) applying a new parametric spherical harmonic technique to estimate the morphological features, (ii) modeling a novel angular invariant gray-level co-occurrence matrix to estimate the textural features, and (iii) constructing wash-in/wash-out slopes to estimate the functional features by quantifying enhancement variations across different CE-CT phases. These features were subsequently combined and processed using a two-stage multilayer perceptron artificial neural network (MLP-ANN) classifier to classify the renal tumor as benign or malignant and identify the malignancy subtype as well. Using the combined features and a leave-one-subject-out cross-validation approach, the developed RC-CAD system achieved a sensitivity of 95.3%±2.0%, a specificity of 99.9%±0.4%, and Dice similarity coefficient of 0.98±0.01 in differentiating malignant from benign tumors, as well as an overall accuracy of 89.6%±5.0% in discriminating ccRCC from nccRCC. The diagnostic abilities of the developed RC-CAD system were further validated using a randomly stratified 10-fold cross-validation approach. The obtained results using the proposed MLP-ANN classification model outperformed other machine learning classifiers (e.g., support vector machine, random forests, relational functional gradient boosting, etc.). Hence, integrating morphological, textural, and functional features enhances the diagnostic performance, making the proposal a reliable noninvasive diagnostic tool for renal tumors.

Deep learning for end-to-end kidney cancer diagnosis on multi-phase abdominal computed tomography

In 2020, it is estimated that 73,750 kidney cancer cases were diagnosed, and 14,830 people died from cancer in the United States. Preoperative multi-phase abdominal computed tomography (CT) is often used for detecting lesions and classifying histologic subtypes of renal tumor to avoid unnecessary biopsy or surgery. However, there exists inter-observer variability due to subtle differences in the imaging features of tumor subtypes, which makes decisions on treatment challenging. While deep learning has been recently applied to the automated diagnosis of renal tumor, classification of a wide range of subtype classes has not been sufficiently studied yet. In this paper, we propose an end-to-end deep learning model for the differential diagnosis of five major histologic subtypes of renal tumors including both benign and malignant tumors on multi-phase CT. Our model is a unified framework to simultaneously identify lesions and classify subtypes for the diagnosis without manual intervention. We trained and tested the model using CT data from 308 patients who underwent nephrectomy for renal tumors. The model achieved an area under the curve (AUC) of 0.889, and outperformed radiologists for most subtypes. We further validated the model on an independent dataset of 184 patients from The Cancer Imaging Archive (TCIA). The AUC for this dataset was 0.855, and the model performed comparably to the radiologists. These results indicate that our model can achieve similar or better diagnostic performance than radiologists in differentiating a wide range of renal tumors on multi-phase CT.

Application of diffusion kurtosis tensor MR imaging in characterization of renal cell carcinomas with different pathological types and grades

Background

To probe the feasibility and reproducibility of diffusion kurtosis tensor imaging (DKTI) in renal cell carcinoma (RCC) and to apply DKTI in distinguishing the subtypes of RCC and the grades of clear cell RCC (CCRCC).

Methods

Thirty-eight patients with pathologically confirmed RCCs [CCRCC for 30 tumors, papillary RCC (PRCC) for 5 tumors and chromophobic RCC (CRCC) for 3 tumors] were involved in the study. Diffusion kurtosis tensor MR imaging were performed with 3 b-values (0, 500, 1000s/mm²) and 30 diffusion directions. The mean kurtosis (MK), axial kurtosis (Ka), radial kurtosis (Kr) values and mean diffusity (MD) for RCC and contralateral normal parenchyma were acquired. The inter-observer agreements of all DKTI metrics of contralateral renal cortex and medulla were evaluated using Bland-Altman plots. Statistical comparisons with DKTI metrics of 3 RCC subtypes and between low-grade (Furman grade I ~ II, 22 cases) and high-grade (Furman grade III ~ IV, 8 cases) CCRCC were performed with ANOVA test and Student t test separately. Receiver operating characteristic (ROC) curve analyses were used to compare the diagnostic efficacy of DKTI metrics for predicting nuclear grades of CCRCC. Correlations between DKTI metrics and nuclear grades were also evaluated with Spearman correlation analysis.

Results

Inter-observer measurements for each metric showed great reproducibility with excellent ICCs ranging from 0.81 to 0.87. There were significant differences between the DKTI metrics of RCCs and contralateral renal parenchyma, also among the subtypes of RCC. MK and Ka values of CRCC were significantly higher than those of CCRCC and PRCC. Statistical difference of the MK, Ka, Kr and MD values were also obtained between CCRCC with high- and low-grades. MK values were more effective for distinguishing between low- and high- grade CCRCC (area under the ROC curve: 0.949). A threshold value of 0.851 permitted distinction with high sensitivity (90.9%) and specificity (87.5%).

Conclusion

Our preliminary results suggest a possible role of DKTI in differentiating CRCC from CCRCC and PRCC. MK, the principle DKTI metric might be a surrogate biomarker to predict nuclear grades of CCRCC.

Trial registration

ChiCTC, ChiCTR-DOD-17010833, Registered 10 March, 2017, retrospectively registered, http://www.chictr.org.cn/showproj.aspx?proj=17559.

Comparative Assessment of the WNT/β-Catenin Pathway, CacyBP/SIP, and the Immunoproteasome Subunit LMP7 in Various Histological Types of Renal Cell Carcinoma

Objective

The Wnt/ß-catenin pathway plays an important role in pathogenesis of variety cancers. Most studies on changes in WNT/β-catenin pathway in renal cell carcinoma (RCC) apply only to clear cell RCC, while there are no comparative assessments of this signaling pathway in various histological types of renal tumors in the available literature. Additionally, considering the close relationship between WNT/β-catenin signaling, CacyBP/SIP and proteasomal activity, it seemed worth comparing WNT/β-catenin pathway, CacyBP/SIP and LMP7 immunoproteasome subunit in human samples of clear cell, papillary, and chromophobe RCC.

Methods

Tests were performed on sections of three types of kidney tumors together with surrounding unchanged tissue fragments collected from 50 patients. Samples were divided into three groups depending on the histological type of cancer: clear cell, papillary and chromophobe RCC. Immunohistochemistry and PCR methods were used to identify WNT10A, Fzd5, β-catenin, GSK-3ß, CacyBP/SIP, LMP7, and gene expression.

Results

Immunoreactivity and expression of WNT10A, Fzd5, β-catenin, GSK-3ß, CacyBP/SIP, LMP7 in clear cell RCC was markedly increased compared to non-cancerous kidney tissue. In papillary RCC, immunoreactivity and expression of WNT/β-catenin pathway, CacyBP/SIP, LMP7 was also increased compared to non-malignant kidneys, but it was less pronounced than in clear cell RCC. The least substantial increase in immunoreactivity and expression of WNT/β-catenin pathway, CacyBP/SIP, LMP7 was found in chromophobe RCC, compared to other RCC histological subtypes studied.

Conclusions

Study results suggest an important role of WNT/β-catenin pathway, CacyBP/SIP and LMP7 in RCC carcinogenesis, and may indicate new aspects of pathomechanisms leading to differences in the biology of clear cell, papillary and chromophobe RCC.

Updates in Histologic Grading of Urologic Neoplasms

CONTEXT.—

Tumor histology offers a composite view of the genetic, epigenetic, proteomic, and microenvironmental determinants of tumor biology. As a marker of tumor histology, histologic grading has persisted as a highly relevant factor in risk stratification and management of urologic neoplasms (ie, renal cell carcinoma, prostatic adenocarcinoma, and urothelial carcinoma). Ongoing research and consensus meetings have attempted to improve the accuracy, consistency, and biologic relevance of histologic grading, as well as provide guidance for many challenging scenarios.

OBJECTIVE.—

To review the most recent updates to the grading system of urologic neoplasms, including those in the 2016 4th edition of the World Health Organization (WHO) Bluebook, with emphasis on issues encountered in routine practice.

DATA SOURCES.—

Peer-reviewed publications and the 4th edition of the WHO Bluebook on the pathology and genetics of the urinary system and male genital organs.

CONCLUSIONS.—

This article summarizes the recently updated grading schemes for renal cell carcinoma, prostate adenocarcinomas, and bladder neoplasms of the genitourinary tract.

Ubiquitin specific peptidase 19 is a prognostic biomarker and affect the proliferation and migration of clear cell renal cell carcinoma

Ubiquitin specific peptidase 19 (USP19) is a member of the USP family and exhibits diverse roles in various biological processes, such as cell differentiation, cell cycle progression and apoptosis. There is limited knowledge regarding the role and impact of USP19 in cancer, particularly clear cell renal cell carcinoma (ccRCC). To examine the function of USP19 in ccRCC, The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus databases were examined to determine USP19 mRNA expression levels. USP19 mRNA levels were significantly lower in ccRCC tissues than in normal tissues. USP19 downregulation was associated with ccRCC progression and poor prognostic outcomes in TCGA cohort. Furthermore, the functional involvement of USP19 in ccRCC was examined using Cell Counting Kit-8, soft agar, Transwell and wound healing assays in vitro following overexpression or knockdown of USP19 in the Caki-1 cell line. USP19 overexpression inhibited ccRCC proliferation and migration, whereas USP19 knockdown promoted ccRCC proliferation and migration in vitro. Consistent with these results, it was further demonstrated that USP19 downregulation promoted tumor growth in vivo in a xenograft model. Mechanistically, it was found that USP19 exerted its inhibitory effect on ccRCC proliferation and migration by suppressing the activation of ERK. Collectively, the present findings identified a role for USP19 as a tumor suppressor in ccRCC and demonstrated that USP19 is a potential prognostic biomarker that could be applied in ccRCC therapy.

Radiologic-Radiomic Machine Learning Models for Differentiation of Benign and Malignant Solid Renal Masses: Comparison With Expert-Level Radiologists

OBJECTIVE. The objective of our study was to compare the performance of radiologicradiomic machine learning (ML) models and expert-level radiologists for differentiation of benign and malignant solid renal masses using contrast-enhanced CT examinations. MATERIALS AND METHODS. This retrospective study included a cohort of 254 renal cell carcinomas (RCCs) (190 clear cell RCCs [ccRCCs], 38 chromophobe RCCs [chrRCCs], and 26 papillary RCCs [pRCCs]), 26 fat-poor angioleiomyolipomas, and 10 oncocytomas with preoperative CT examinations. Lesions identified by four expert-level radiologists (> 3000 genitourinary CT and MRI studies) were manually segmented for radiologicradiomic analysis. Disease-specific support vector machine radiologic-radiomic ML models for classification of renal masses were trained and validated using a 10-fold cross-validation. Performance values for the expert-level radiologists and radiologic-radiomic ML models were compared using the McNemar test. RESULTS. The performance values for the four radiologists were as follows: sensitivity of 73.7-96.8% (median, 84.5%; variance, 122.7%) and specificity of 48.4-71.9% (median, 61.8%; variance, 161.6%) for differentiating ccRCCs from pRCCs and chrRCCs; sensitivity of 73.7-96.8% (median, 84.5%; variance, 122.7%) and specificity of 52.8-88.9% for differentiating ccRCCs from fat-poor angioleiomyolipomas and oncocytomas (median, 80.6%; variance, 269.1%); and sensitivity of 28.1-60.9% (median, 84.5%; variance, 122.7%) and specificity of 75.0-88.9% for differentiating pRCCs and chrRCCs from fat-poor angioleiomyolipomas and oncocytomas (median, 50.0%; variance, 191.1%). After a 10-fold cross-validation, the radiologic-radiomic ML model yielded the following performance values for differentiating ccRCCs from pRCCs and chrRCCs, ccRCCs from fat-poor angioleiomyolipomas and oncocytomas, and pRCCs and chrRCCs from fat-poor angioleiomyolipomas and oncocytomas: a sensitivity of 90.0%, 86.3%, and 73.4% and a specificity of 89.1%, 83.3%, and 91.7%, respectively. CONCLUSION. Expert-level radiologists had obviously large variances in performance for differentiating benign from malignant solid renal masses. Radiologic-radiomic ML can be a potential way to improve interreader concordance and performance.

Frequency, incidence and survival outcomes of clear cell renal cell carcinoma in the United States from 1973 to 2014: A SEER-based analysis

The epidemiological and prognostic data focusing on clear cell renal cell carcinoma (ccRCC) are rarely presented. This study was aimed to define the frequency, incidence, and survival outcomes of ccRCC in the United States.The Surveillance, Epidemiology, and End Results (SEER) database was searched for patients with ccRCC from 1973 to 2014. Two patient cohorts were utilized: patient cohorts of SEER 18 registries and 9 registries. Overall survival was determined with Kaplan-Meier method and compared across groups with log-rank test.The incidence rate of ccRCC increased with advancing age, peaked in individuals aged 60 to 79 years, and declined in individuals aged ≥80 years. The incidence rate of ccRCC was significantly higher in males than females (1.94: 1, P < .0001), in Whites than Blacks or others (1:0.79:0.91, P < .0001). The incidence rate of ccRCC with right side as primary origin was slightly but significantly higher than that with left side as primary origin (1:0.96, P = .0006). The incidence rate of ccRCC in Grade II was higher than other grades. Generally, the incidence rates of ccRCC in most circumstances started to surge in the middle 1990s. Survival outcomes of ccRCC worsened with advancing age at diagnosis, tumor grade, and stage. A better prognosis was observed in females than males, in Whites than Blacks, and in individuals diagnosed in 2006 to 2014 than 1973 to 2005.To the best of our knowledge, the present study firstly presented long-term and updated epidemiological and prognostic data concerning ccRCC in the United States. Significant differences in incidence rates and survival outcomes stratified by different variables were identified.

Proximal CD13 Versus Distal GATA-3 Expression in Renal Neoplasia According to WHO 2016 Classification

Little is known about the aminopeptidase CD13 in renal neoplasia according to the new 2016 World Health Organization renal tumor classification. We selected 175 cases, including 79 clear cell, 31 papillary, 24 chromophobe, 8 clear cell papillary renal cell carcinomas (RCCs), 21 oncoytomas, and 12 microphthalmia transcription factor family translocation RCCs: 4 t(6;11)/transcription factor EB (TFEB), 7 t(Xp11) with 2 cystic variants and 1 t(X;17). GATA binding protein 3 (GATA-3) was inserted as control. Expression of proximal antigen CD13 was observed in 63/79 (80%) clear cell, 25/31 (81%) papillary, 3/8 (37%) clear cell papillary, 1/4 (25%) t(6;11)/TFEB, 2/7 (28%) cystic t(Xp11), and in 1/1 t(X;17) RCCs. All chromophobe RCC (0/24) and all oncocytomas (0/21) resulted negative. CD10 was seen in 76/79 (96%) clear cell, 15/31 (48%) papillary, 10/24 (42%) chromophobe, 1/8 (12%) clear cell papillary RCCs, 4/21 (19%) oncocytomas, 1/4 (25%) t(6;11)/TFEB, 2/7 (29%) cystic t(Xp11), and in 1/1 t(X;17) RCCs. GATA-3 was positive in 3/7 (42%) clear cell papillary RCCs and negative in all remaining RCCs, except a single chromophobe RCC and a single oncocytoma. We concluded that: (1) CD13 and GATA-3 immunostains may serve as a diagnostic aid in differentiating subtypes of RCC; (2) CD13 is always absent in chromophobe RCC and oncocytomas, whereas CD10 can be immunoexpressed in both; (3) CD13 should be included in a panel of antibodies to distinguish "proximal renal tumors" from "distal renal tumors" and between clear cell RCC versus microphthalmia transcription factor family translocations RCCs; and (4) when present, GATA-3 is specific for clear cell papillary RCC.

The Role of Hematological Parameters in Predicting Fuhrman Grade and Tumor Stage in Renal Cell Carcinoma Patients Undergoing Nephrectomy

Background and objective: We investigated the ability of preoperative serum values of red blood cell distribution width (RDW), neutrophil lymphocyte ratio (NLR) and plateletcrit (PCT) to predict Fuhrman grades (FG) and tumor stages of renal cell carcinoma in patients who underwent radical nephrectomy. Materials and methods: Records of 283 patients that underwent radical or partial nephrectomy of renal masses at our clinic between January 2010 and April 2018, whose pathology results indicated renal cell carcinoma (RCC), and who had their FG and T1–4 N0M0 identified were retrospectively evaluated. The patients were divided into two groups based on their FG as low (I–II) and high (III–IV) and their T stages were similarly grouped as limited to kidney (pT1–pT2) and not limited to kidney (pT3–pT4). Results: Mean RDW, NLR, PCT cut-off values of the patients for FG and T stage were 15.65%, 3.54, 0.28% and 14.35%, 2.69, 0.28%, respectively. The RDW and NLR were determined to be statistically significant predictors of a pathologically high FG, whereas the PCT value was not a statistically significant predictor of high FG (p = 0.003, p = 0.006, p = 0.075, respectively). The relationship of RDW, NLR and PCT values with a limited to the kidney pathological T stage revealed statistically significant correlations for all three values. Conclusions: We determined that only RDW and NLR were markers predicting FG, while PCT had no prognostic value. On the other hand, all three of these values were associated with a limited to the kidney pathological T stage in patients who underwent nephrectomy due to renal masses and whose pathologies suggested RCC.

Nomograms for predicting long-term overall survival and disease-specific survival of patients with clear cell renal cell carcinoma

Objectives

The aim of this study was to establish comprehensive and practical nomograms, based on significant clinicopathological parameters, for predicting the overall survival (OS) and the disease-specific survival (DSS) of patients with clear cell renal cell carcinoma (ccRCC).

Patients and methods

The data of 35,151 ccRCC patients, diagnosed between 2004 and 2014, were obtained from the database of the Surveillance, Epidemiology, and End Results (SEER) program. The Kaplan–Meier method and Cox proportional hazards regression model were used to evaluate the prognostic effects of multiple clinicopathological variables on survival. Based on Cox models, a nomogram was constructed to predict the probabilities of OS and DSS for an individual patient. The predictive performance of nomograms was evaluated using the concordance index (C-index) and calibration curves.

Results

According to univariate and multivariate analyses, age at diagnosis, sex, race, marital status, surgical approach, tumor node metastasis (TNM) stage, and Fuhrman grade significantly correlated with the survival outcomes. These characteristics were used to establish nomograms. The nomograms showed good accuracy in predicting 3-, 5-, and 10-year OS and DSS, with a C-index of 0.79 (95% CI, 0.79–0.80) for OS and 0.87 (95% CI, 0.86–0.88) for DSS. All calibration curves revealed excellent consistency between predicted and actual survival.

Conclusion

Nomograms were developed to predict death from ccRCC treated with nephrectomy. These new prognostic tools could aid in improving the predictive accuracy of survival outcomes, thus leading to reasonable individualized treatment.

Verification of the International Society of Urological Pathology recommendations in Japanese patients with clear cell renal cell carcinoma

The aim of the present study was to evaluate the validity of potential prognostic parameters of clear cell renal cell carcinoma (ccRCC) recommended by the 2012 International Society of Urological Pathology (ISUP) Consensus Conference in the Japanese population. We reviewed 406 Japanese patients with localized or locally advanced ccRCC who underwent curative surgery during 2004-2014 at Tokai University Hospital (Isehara, Japan) and were followed up for >2 years after surgery. A single pathologist reviewed all the histological slides. Morphological subtype and pathological T stage were reassigned according to the 2016 World Health Organization and TNM classifications. Sarcomatoid differentiation (SD), rhabdoid differentiation (RD), tumor necrosis (TN) and microvascular invasion (MVI) were assessed according to the 2012 ISUP recommendations. Nuclear grade was reclassified according to both the Fuhrman and the ISUP grading systems. Recurrence‑free survival (RFS) and cancer-specific survival (CSS) were assessed through univariate and multivariate analyses. According to the Fuhrman grading system (group Fuhrman), TN and MVI were independent risk factors for postoperative recurrence in the multivariate analysis using the Cox proportional hazards model. According to the ISUP grading system (group ISUP), TN and MVI were independent risk factors for postoperative recurrence. In group Fuhrman, age, Fuhrman grade and TN were independent risk factors for CSS. In group ISUP, age, ISUP grade, and TN were independent risk factors for CSS. Furthermore, the group that was upgraded from Fuhrman grade 2 to ISUP grade 3 exhibited poorer CSS compared with the group that was reclassified from Fuhrman grade 2 to ISUP grade 2 (non-upgraded). Regardless of the nuclear grade, TN remained an independent predictor of RFS and CSS. To the best of our knowledge, this is the first report to prove the correlation between the 2012 ISUP recommendations and clinical outcomes in a Japanese ccRCC cohort. TN and upgrading to ISUP grade 3 were found to be potentially useful independent indicators of postoperative prognosis.

Chemical shift magnetic resonance imaging for distinguishing minimal-fat renal angiomyolipoma from renal cell carcinoma: a meta-analysis

OBJECTIVES

To determine the performance of chemical shift signal intensity index (CS-SII) values for distinguishing minimal-fat renal angiomyolipoma (mfAML) from renal cell carcinoma (RCC) and to assess RCC subtype characterisation.

METHODS

We identified eligible studies on CS magnetic resonance imaging (CS-MRI) of focal renal lesions via PubMed, Embase, and the Cochrane Library. CS-SII values were extracted by lesion type and evaluated using linear mixed model-based meta-regression. RCC subtypes were analysed. Two-sided p value <0.05 indicated statistical significance. Methodological quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies 2 tool.

RESULTS

Eleven articles involving 850 patients were included. Minimal-fat AML had significantly higher CS-SII value than RCC (p < 0.05); there were no significant differences between mfAML and clear cell RCC (cc-RCC) (p = 0.112). Clear cell RCC had a significantly higher CS-SII value than papillary RCC (p-RCC) (p < 0.001) and chromophobe RCC (ch-RCC) (p = 0.045). The methodological quality was relatively high, and Begg's test data points indicated no obvious publication bias.

CONCLUSIONS

The CS-SII value for differentiating mfAML from cc-RCC remains unproven, but is a promising method for differentiating cc-RCC from p-RCC and ch-RCC.

KEY POINTS

• RCC CS-SII values are significantly lower than those of mfAML overall. • CS-SII values cannot aid differentiation between mfAML and cc-RCC. • CS-SII values might help characterise RCC subtypes.

Clear cell renal cell carcinoma: validation of World Health Organization/International Society of Urological Pathology grading

AIMS

In 2012, the International Society of Urological Pathology (ISUP) introduced a novel grading system for clear cell renal cell carcinoma (ccRCC) and papillary renal cell carcinoma. This system is incorporated into the latest World Health Organization renal tumour classification, being designated WHO/ISUP grading. This study was undertaken to compare WHO/ISUP and Fuhrman grading and to validate WHO/ISUP grading as a prognostic parameter in a series of clear cell RCC.

METHODS AND RESULTS

Analysis of 681 cases of ccRCC showed that 144 tumours could not be assigned a Fuhrman grade on the basis of ambiguous grading features. The application of WHO/ISUP grading resulted in a general down-grading of cases when compared with Fuhrman grading. In a sub-group of 374 cases, for which outcome data were available, 9.3% were WHO/ISUP grade 1, 50.3% were grade 2, 24.1% grade 3 and 16.3% grade 4, while the distribution of Fuhrman grades was 0.4% grade 1, 48.7% grade 2, 29.4% grade 3 and 21.5% grade 4. There were no recurrence/metastases amongst patients with WHO/ISUP grade 1 tumours and there was a significant difference in outcome for WHO/ISUP grades 2, 3 and 4. For Fuhrman grading the cancer-free survival was not significantly different for grade 2 and grade 3 tumours. On multivariate analysis WHO/ISUP grade and pT staging category were found to retain prognostic significance.

CONCLUSIONS

The study demonstrates that FG cannot be applied in >20% of cases of ccRCC and the WHO/ISUP provides superior prognostic information.

Renal cell carcinoma histological subtype distribution differs by age, gender, and tumor size in coastal Chinese patients

The distribution pattern of renal cell carcinoma (RCC) histological subtypes according to age, gender and tumor size has not been well illustrated in RCC patients living in fast-developing regions of China. We recruited 2941 patients with clear cell renal cell carcinoma (ccRCC), papillary renal cell carcinoma (PCC) or chromophobe from two hospitals in coastal China (2004−2012) consecutively and draw 538 American Chinese RCC patients’ data with time matched from the Surveillance, Epidemiology, and End Results database. We found that compared with ccRCC patients, chromophobe patients were more likely to be female (OR: 2.538, 95% CI: 1.923−3.350), younger (OR for 51−60 years old: 0.686; OR for over 60 years old: 0.478; reference: age < 50) and to have a larger maximal diameter (Dmax) (OR for Dmax > 7 cm: 1.883; reference: Dmax ≤ 4 cm). Besides, in comparison with coastal Chinese patients, American Chinese individuals had lower Fuhrman grades (P < 0.001) and had an onset age 10 years delay. In conclusion, we were the first to observe marked gender, age and tumor size differences in the proportional subtype distribution of RCCs in coastal Chinese patients, and also the first to compare coastal Chinese with American Chinese data.

Correlating Preoperative Imaging with Histologic Subtypes of Renal Cell Carcinoma and Common Mimickers

Renal cell carcinoma (RCC) consists of distinct subtypes that have unique pathologic and imaging features as well as specific cytogenetic and molecular characteristics. As the prognosis and therapeutic strategies may differ for each subtype, correlation of the preoperative imaging with the pathologic findings is of great clinical relevance. In addition, differentiation of RCC from benign entities is ideal in order to prevent overtreatment. However, a noninvasive diagnosis with imaging alone is not always straightforward due to the overlapping appearance of RCC with benign lesions such as fat-poor angiomyolipoma and oncocytoma. With new imaging modalities, there have been significant improvements in correlating preoperative imaging with pathologic characteristics. These new discoveries are able to aid in a more specific, noninvasive, diagnosis that in turn helps direct patient management.

Cystic and necrotic papillary renal cell carcinoma: prognosis, morphology, immunohistochemical, and molecular-genetic profile of 10 cases

Conflicting data have been published on the prognostic significance of tumor necrosis in papillary renal cell carcinoma (PRCC). Although the presence of necrosis is generally considered an adverse prognostic feature in PRCC, we report a cohort of 10 morphologically distinct cystic and extensively necrotic PRCC with favorable biological behavior. Ten cases of type 1 PRCC with a uniform morphologic pattern were selected from the 19 500 renal tumors, of which 1311 were PRCCs in our registry. We focused on precise morphologic diagnosis supported by immunohistochemical and molecular-genetic analysis. Patients included 8 men and 2 women with an age range of 32-85 years (mean, 62.6 years). Tumor size ranged from 6 to 14 cm (mean, 9.4 cm). Follow-up data were available in 7 patients, ranging from 0.5 to 14 years (mean, 4 years). All tumors were spherical, cystic, and circumscribed by a thick fibrous capsule, filled with hemorrhagic/necrotic contents. Limited viable neoplastic tissue was present only as a thin rim in the inner surface of the cyst wall, consistent with type 1 PRCC. All cases were positive for AMACR, OSCAR, CAM 5.2, HIF-2, and vimentin. Chromosome 7 and 17 polysomy was found in 5 of 9 analyzable cases, 2 cases demonstrated chromosome 7 and 17 disomy, and 1 case showed only chromosome 17 polysomy. Loss of chromosome Y was found in 5 cases, including 1 case with disomic chromosomes 7 and 17. No VHL gene abnormalities were found. Papillary renal cell carcinoma type 1 can present as a large hemorrhagic/necrotic unicystic lesion with a thick fibroleiomyomatous capsule. Most cases showed a chromosomal numerical aberration pattern characteristic of PRCC. All tumors followed a nonaggressive clinical course. Large liquefactive necrosis should not necessarily be considered an adverse prognostic feature, particularly in a subset of type 1 PRCC with unilocular cysts filled with necrotic/hemorrhagic material.

Adult Renal Cell Carcinoma: A Review of Established Entities from Morphology to Molecular Genetics

According to the current World Health Organization (WHO), renal cell carcinomas (RCCs) that primarily affect adults are classified into 8 major subtypes. Additional emerging entities in renal neoplasia have also been recently recognized and these are discussed in further detail by Mehra et al (Emerging Entities in Renal Neoplasia, Surgical Pathology Clinics, 2015, Volume 8, Issue 4). In most cases, the diagnosis of a RCC subtype can be based on morphologic criteria, but in some circumstances the use of ancillary studies can aid in the diagnosis. This review discusses the morphologic, genetic, and molecular findings in RCCs previously recognized by the WHO, and provides clues to distinction from each other and some of the newer subtypes of RCC. As prognosis and therapeutic options vary for the different subtypes of RCC, accurate pathologic distinction is critical for patient care.

Intratumor Heterogeneity of Perfusion and Diffusion in Clear-Cell Renal Cell Carcinoma: Correlation With Tumor Cellularity

BACKGROUND

Magnetic resonance imaging (MRI) has the potential to noninvasively provide information about the tumor microenvironment. A correlation between arterial spin-labeled (ASL) MRI and tumor vasculature has been previously demonstrated; however, its correlation with tumor cellularity is unknown. We sought to assess intratumor heterogeneity of perfusion and diffusion in vivo in clear-cell renal cell carcinoma (ccRCC) using MRI and to correlate these findings with tumor vascularity and cellularity at histopathology.

PATIENTS AND METHODS

Twenty-three ccRCC patients underwent ASL and diffusion-weighted MRI before surgery after signing an informed consent in this prospective institutional review board-approved, HIPAA (Insurance Portability and Accountability Act)-compliant study. Quantitative ASL perfusion and diffusion were measured in 2 areas within the same tumor with high and low perfusion. Microvessel density (MVD) on CD31 and CD34 immunostains and tumor cellularity in anatomically coregistered tissue samples were correlated to MRI measurements (Spearman; P < .05 statistically significant).

RESULTS

ASL perfusion (P < .0001), CD31 MVD (P = .02), CD34 MVD (P = .04), and cellularity (P = .002) from high and low perfusion areas were significantly different across all tumors. There were positive correlations between tumor cellularity and CD31 MVD (ρ = 0.350, P = .021), CD31 and CD34 MVD (ρ = 0.838, P < .0001), ASL perfusion and cellularity (ρ = 0.406, P = .011), and ASL perfusion and CD31 MVD (ρ = 0.468, P = .003), and a negative correlation between tissue diffusion coefficient and cellularity (ρ = -0.316, P = .039).

CONCLUSION

Tumor areas with high ASL perfusion exhibit higher cellularity and MVD compared to areas with low perfusion in the same tumor. A positive correlation between tumor vascularity and cellularity in ccRCC is newly reported. A negative correlation between tumor diffusion and cellularity is confirmed.

Comparison of 11C-4DST and 18F-FDG PET/CT imaging for advanced renal cell carcinoma: preliminary study

PURPOSE

4'-[Methyl-(11)C]-thiothymidine (4DST) has been developed as an in vivo cell proliferation marker based on its DNA incorporation mechanism. This study evaluated the potential of 4DST PET/CT for imaging cellular proliferation in advanced clear cell renal cell carcinoma (RCC), compared with FDG PET/CT. Both 4DST and FDG uptake were compared with biological findings based on surgical pathology.

METHODS

Five patients (3 men and 2 women; mean (±SD) age 64.8 ± 11.0 years) with a single RCC (mean diameter: 9.3 ± 3.2 cm) were examined by PET/CT using 4DST and FDG. The dynamic emission scan of 4DST for RCC over 35 min followed by a static emission scan of the body for 4DST and FDG. Then we compared the maximum standardized uptake value (SUVmax) of 20 areas of RCC on both 4DST and FDG images with (1) the Ki-67 index of cellular proliferation (2) Fuhrman grade system for nuclear grade (G) in RCC and (3) pathological phosphorylated grade of mammalian target of rapamycin (pmTOR).

RESULTS

All patient cases showed clear uptake of FDG and 4DST in RCC tumors, with mean 4DST SUVmax of 7.3 ± 2.2 (range 4.3-9.4) and mean FDG SUVmax of 6.0 ± 2.8 (range 3.4-10.4). The correlation coefficient between SUVmax and Ki-67 index was higher with 4DST (r = 0.61) than with FDG (r = 0.43). Tumor 4DST uptake (G0: 1.4, G2: 2.6, G2 5.6, G4: 5.7) and tumor FDG uptake (G0: 1.8, G2: 2.9, G2 3.7, G4: 4.1) were both related to Fuhrman grade system. The 4DST uptake increased as the pmTOR grade increases (G0: 3.1, G1: 4.8, G2: 4.7, G3: 6.2); in contrast FDG uptake was unrelated to pmTOR grade (G0: 2.8, G2: 4.0, G2 3.3, G4: 3.6).

CONCLUSION

A higher correlation with the proliferation of RCC was observed for 4DST than for FDG. The 4DST uptake exhibits the possibility to predict pmTOR grade, indicating that 4DST has potential for the evaluation of therapeutic effect with mTOR inhibitor in patients with RCC.

Clinically localized type 1 and 2 papillary renal cell carcinomas have similar survival outcomes following surgery

PURPOSE

We aimed to determine incidence, pathologic findings, prognostic factors and clinical outcomes for patients with clinically localized papillary RCC.

METHODS

Demographic, clinical and pathologic findings were collected on all patients with PRCC undergoing surgery at four academic medical centers. The primary endpoint was cancer-specific survival (CSS). Relapse-free survival (RFS) and overall survival (OS) were secondary endpoints. Kaplan-Meier estimates were obtained, and Cox proportional hazard regression models were used to assess predictors of mortality and relapse.

RESULTS

We identified 626 PRCC, of which 373 (60 %) were type 1 and 253 (40 %) were type 2, with three-quarters of all tumors being pT1. Compared to patients with type 1, those with type 2 were older (mean age: 63 vs 61; p = 0.02), presented more commonly with symptoms (13 vs 7 %; p = 0.02) and had larger mean tumor size (5.2 vs 4.3 cm; p = 0.001). With a median follow-up of 41 months (IQR: 16-68), 92 patients had died of PRCC (15 %), 48 (8 %) experienced relapse, and 101 died from all causes (16 %). The estimated 5-year CSS, RFS and OS were 83, 91 and 82 %, respectively. In multivariable analysis, older age, T stage and nodal status were predictors of CSS and OS. However, PRCC subtype was not a predictor of CSS, RFS or OS.

CONCLUSION

While patients with type 2 PRCC appear to present with more advanced disease than patients with type 1, PRCC subtype does not appear to be an independent predictor of CSS, RFS or OS for treated localized disease.

18-F fluorodeoxyglucose uptake in positron emission tomography as a pathological grade predictor for renal clear cell carcinomas

OBJECTIVES

To evaluate the usefulness of Fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (18-F FDG-PET/CT) in the prediction of Fuhrman pathological grades of renal clear cell carcinoma (cRCC).

METHODS

This retrospective study was approved by our institutional review board, and written informed consent was waived. Thirty-one patients with pathologically proven cRCC underwent 18-F FDG-PET/CT for tumour staging. Maximum standardized uptake value of cRCC (tumour SUVmax) and mean SUV of the liver and spleen (liver and spleen SUVmean) were measured by two independent observers. Tumour SUVmax, tumour-to-liver SUV ratio, and tumour-to-spleen SUV ratio were correlated with the pathological grades.

RESULTS

Logistic analysis demonstrated that only the tumour-to-liver SUV ratio was a significant parameter for differentiating high-grade (Fuhrman grades 3 and 4) tumours from low-grade (Fuhrman grades 1 and 2) tumours (P = 0.007 and 0.010 for observers 1 and 2, respectively). Sensitivity, specificity, and positive and negative predictive values for detecting tumours of Fuhrman grades 3 and 4 were 64, 100, 100, and 77%, respectively, for observer 1, and 79, 88, 85, and 83%, respectively, for observer 2.

CONCLUSIONS

The tumour-to-liver SUV ratio with 18-F FDG-PET/CT appeared to be a valuable imaging biomarker in the prediction of high-grade cRCC.

KEY POINTS

• Tumour SUV max was correlated with the Fuhrman grades. • High-grade tumours have significantly higher SUV max than low-grade tumours. • Tumour-to-liver SUV ratio is useful in the prediction of high-grade cRCC.

Multiparametric magnetic resonance imaging for the differentiation of low and high grade clear cell renal carcinoma

PURPOSE

To retrospectively evaluate the ability of magnetic resonance (MR) imaging to differentiate low from high Fuhrman grade renal cell carcinoma (RCC).

MATERIALS AND METHODS

MR images from 80 consecutive pathologically proven RCC (57 clear cell, 16 papillary and 7 chromophobe) were evaluated. Double-echo chemical shift, dynamic contrast-enhanced T1- and T2-weighted images and apparent diffusion coefficient (ADC) maps were reviewed independently. Signal intensity index (SII), tumour-to-spleen SI ratio (TSR), ADC ratio, wash-in (WiI) and wash-out indices (WoI) between different phases were calculated and compared to pathological grade and size. The Fuhrman scoring system was used. Low grade (score ≤ 2) and high grade (score ≥ 3) tumours were compared using univariate and multivariate analyses.

RESULTS

No associations between grade and imaging factors were found for papillary and chromophobe RCCs. For clear cell RCCs, there was a significant association between the grade and parenchymal WiI (WiI2) (P = 0.02) or ADCr (P = 0.03). A significant association between tumour grade and size (P = 0.01), WiI2 (P = 0.02) and ADCr (P = 0.05) remained in multivariate analysis.

CONCLUSIONS

Multiparametric MRI can be used to accurately differentiate low Fuhrman grade clear cell RCC from high grade. High Fuhrman grade (≥ 3) RCCs were larger, had lower parenchymal wash-in indices and lower ADC ratios than low grade.

KEY POINTS

• Fuhrman grade of clear cell RCC can be differentiated with multiparametric MR imaging. • Fuhrman grade significantly differed for size, parenchymal wash-in index and ADC ratio. • No significant associations were found for papillary and chromophobe renal cell carcinoma.

The ISUP system of staging, grading and classification of renal cell neoplasia

There have been significant changes in the staging, classification and grading of renal cell neoplasia in recent times. Major changes have occurred in our understanding of extra-renal extension by renal cell cancer and how gross specimens must be handled to optimally display extra-renal spread. Since the 1981 World Health Organization (WHO) classification of renal tumors, in which only a handful of different entities were reported, many new morphological types have been described in the literature, resulting in 50 different entities reported in the 2004 WHO classification. Since 2004, further new entities have been recognized and reported necessitating an update of the renal tumor classification. There have also been numerous grading systems for renal cell carcinoma with Fuhrman grading, the most widely used system. In recent times, the prognostic value and the applicability of the Fuhrman grading system in practice has been shown to be, at best, suboptimal. To address these issues and to recommend reporting guidelines, the International Society of Urological Pathology (ISUP) undertook a review of adult renal neoplasia through an international consensus conference in Vancouver in 2012. The conduct of the conference was based upon evidence from the literature and the current practice amongst recognized experts in the field. Working groups selected to deal with key topics evaluated current data and identified points of controversy. A pre-meeting survey of the ISUP membership was followed by the consensus conference at which a formal ballot was taken on each key issue. A 65% majority vote was taken as consensus. This review summarizes the outcome and recommendations of this conference with regards to staging, classification and grading of renal cell neoplasia.

Racial difference in histologic subtype of renal cell carcinoma

In the United States, renal cell carcinoma (RCC) has rapidly increased in incidence for over two decades. The most common histologic subtypes of RCC, clear cell, papillary, and chromophobe have distinct genetic and clinical characteristics; however, epidemiologic features of these subtypes have not been well characterized, particularly regarding any associations between race, disease subtypes, and recent incidence trends. Using data from the Surveillance, Epidemiology, and End Results (SEER) Program, we examined differences in the age-adjusted incidence rates and trends of RCC subtypes, including analysis focusing on racial differences. Incidence rates increased over time (2001-2009) for all three subtypes. However, the proportion of white cases with clear cell histology was higher than among blacks (50% vs. 31%, respectively), whereas black cases were more likely than white cases to have papillary RCC (23% vs. 9%, respectively). Moreover, papillary RCC incidence increased more rapidly for blacks than whites (P < 0.01) over this period. We also observed that increased incidence of papillary histology among blacks is not limited to the smallest size strata. We observed racial differences in proportionate incidence of RCC subtypes, which appear to be increasing over time; this novel finding motivates further etiologic, clinical, molecular, and genetic studies.

Attenuation of krüppel-like factor 4 facilitates carcinogenesis by inducing g1/s phase arrest in clear cell renal cell carcinoma

Krüppel-like factor 4 (KLF4) is a transcription factor with diverse functions in various cancer types; however, the function of KLF4 in clear cell renal cell carcinoma (ccRCC) carcinogenesis remains unknown. In this study, we initially examined KLF4 expression by using a cohort of surgically removed ccRCC specimens and cell lines. Results indicated that the transcription and translation of KLF4 were lower in ccRCC tissues than in patient-matched normal tissues. Furthermore, the KLF4 expression was significantly downregulated in the five ccRCC cell lines at protein and mRNA levels compared with that in normal renal proximal tubular epithelial cell lines (HKC). KLF4 downregulation was significantly correlated with tumor stage and tumor diameter. Promoter hypermethylation may contribute to its low expression. In addition, in vitro studies indicated that the KLF4 overexpression significantly inhibited proliferation in human ccRCC cell lines 786-O and ACHN. Moreover, the KLF4 overexpression arrested the cell cycle progress at the G1/S phase transition by upregulating p21^WAF1/CIP1 expression and downregulating cyclin D1 expression, KLF4 knockdown in HKC cells did the opposite. In vivo studies confirmed the anti-proliferative effect of KLF4. Our results suggested that KLF4 had an important function in suppressing the growth of ccRCC.

EADC Values in Diagnosis of Renal Lesions by 3.0 T Diffusion-Weighted Magnetic Resonance Imaging: Compared with the ADC Values

Exponential apparent diffusion coefficient (EADC) is an indicator of diffusion-weighted imaging (DWI) and reflects the pathological changes of tissues quantitatively. However, no study has been investigated in the space-occupying kidney disease using EADC values. This study aims to evaluate the diagnostic role of EADC values at a high magnetic field strength (3.0 T) in kidney neoplastic lesions, compared with that of the ADC values. Ninety patients with suspected renal tumors (including 101 suspected renal lesions) and 20 healthy volunteers were performed MRI scanning. Diffusion-weighted imaging was performed with a single-shot spin-echo echo-planar imaging (SE-EPI) sequence at a diffusion gradient of b = 500 s/mm². We found renal cell carcinoma (RCC) can be distinguished from angiomyolipoma, and clear cell carcinoma can be distinguished from non-clear cell carcinoma by EADC value. There was significant difference in overall EADC values between renal cell carcinoma (0.150 ± 0.059) and angiomyolipoma (0.270 ± 0.108) when b value was 500 s/mm². When receiver operating characteristic (ROC) was higher than 0.192, the sensitivity and specificity of EADC value of renal cell carcinoma were 84.6 and 81.1 %, respectively. In conclusion, EADC map shows the internal structure of the kidney tumor more intuitively than the ADC map dose, and is also in line with the observation habits of the clinicians. EADC can be used as an effective imaging method for tumor diagnosis.

Multiphasic contrast-enhanced MRI: single-slice versus volumetric quantification of tumor enhancement for the assessment of renal clear-cell carcinoma fuhrman grade

PURPOSE

To assess the association between clear-cell carcinoma pathology grade at nephrectomy and magnetic resonance imaging (MRI) tumor enhancement.

MATERIALS AND METHODS

The Institutional Review Board approved this retrospective study and waived the informed consent requirement. In all, 32 patients underwent multiphase contrast-enhanced MRI prior to nephrectomy. MRI tumor enhancement was measured using two approaches: 1) the most enhancing portion of the tumor on a single slice and 2) volumetric analysis of enhancement in the entire tumor. Associations between pathological grade, tumor size, and enhancement were evaluated using the Kruskal-Wallis test and generalized logistic regression models.

RESULTS

No significant association between pathology grade and enhancement was found when measurements were made on a single slice. When measured in the entire tumor, significant associations were found between higher pathology grades and lower mean, median, top 10%, top 25%, and top 50% tumor enhancement (P < 0.001-0.002). On multivariate analysis the association between grade and enhancement remained significant (P = 0.041-0.043), but tumor size did not make an additional contribution beyond tumor enhancement alone in differentiating between tumor grades.

CONCLUSION

There is significant association between tumor grade and enhancement, but only when measured in the entire tumor and not on the most enhancing portion on a single slice.

Diffusion-weighted MRI in renal cell carcinoma: a surrogate marker for predicting nuclear grade and histological subtype

BACKGROUND

Though previous investigators have attempted to evaluate its utility in characterization of focal renal lesions, diffusion-weighted MR imaging (DW MRI) in renal diseases is still an evolving field and its role in predicting the aggressiveness of renal cell carcinoma (RCC) is yet to be established.

PURPOSE

To assess whether apparent diffusion coefficient (ADC) values can be used to determine the nuclear grade and histological subtype of RCCs and to identify the tumor attributes contributing to variation in ADC values.

MATERIAL AND METHODS

The institutional ethics committee waived the requirement of informed consent for this retrospective study. The study cohort consisted of 33 patients who underwent MRI (with diffusion-weighted imaging at b values of 0 and 500 s/mm(2)) and were found to have 36 pathologically-proven RCCs. ADC values were determined for solid portions of RCC, cystic/hemorrhagic areas, and normal renal parenchyma. Histological subtype, nuclear grade, and cell count were determined for each lesion. ADC values were compared between different grades and subtypes and correlation with cell count was investigated. Receiver operating characteristic curves were drawn to establish cut-off ADC values.

RESULTS

There were 23 low grade (grades I and II) and 13 high grade tumors (grades III and IV). There were 32 clear-cell and four non-clear-cell RCCs. A decreasing trend of ADC values was seen with increasing grade and mean ADC of high grade RCC was significantly lower than low grade (1.3145 vs 1.6982 × 10(-3) mm(2)/s) (P = 0.005). Mean ADC for clear-cell RCC was significantly higher than non-clear-cell RCC (1.6245 vs. 1.0412 × 10(-3) mm(2)/s) (P = 0.005). ADC values higher than 1.7960 × 10(-3) mm(2)/s were seen only with low grade and values greater than 1.4904 × 10(-3) mm(2)/s were seen only with clear-cell RCC.

CONCLUSION

ADC values provide a non-invasive means to predict the nuclear grade and histological subtype of RCC. Cellularity and morphology are other tumor attributes contributing to the variation in ADC values of RCCs.

[Incidence and long-term prognosis of papillary renal cancer. Results of a retrospective multicenter study]

OBJECTIVES

Papillary renal cell carcinoma (pRCC) represents the largest subgroup of non-clear-cell kidney cancer. In this retrospective multicenter study, we assessed tumor characteristics and long-term prognosis of patients with pRCC in comparison with conventional clear-cell cancer (ccRCC).

METHODS

We evaluated 2,804 patients who had undergone renal surgery for pRCC or ccRCC between 1990 and 2006. The mean follow-up was 65 months.

RESULTS

Both pRCC and ccRCC groups were comparable concerning age, tumor grade and the incidence of regional lymph node metastasis at diagnosis. The percentage of male patients was higher in pRCC than in ccRCC (76.0% vs. 63.6%), pRCC patients suffered less often from advanced tumors (22.3% vs. 38.1%), visceral metastasis at diagnosis (8.1% vs. 14.5%) and died less frequently due to RCC progression (16.3% vs. 29.6%). Applying multivariable analyses pRCC was found to be an independent predictor of a favorable clinical course for patients with organ-confined RCC. In contrast in advanced disease papillary histology was significantly associated with a poor prognosis and early tumour-related death.

CONCLUSIONS

pRCC seem to be stratified into two different prognostic groups. Localized pRCC has a significantly better prognosis than ccRCC. In contrast, advanced pRCC is characterized by a worse clinical outcome. Whether these two different pRCC cohorts are consistent with the recently defined types 1 and 2 pRCC subtypes or are characterized by other typical genetic alterations, which would lead to a novel pRCC subclassification is currently under investigation within the German Renal Cancer Network.

Immunoexpression status and prognostic value of mTOR and hypoxia-induced pathway members in primary and metastatic clear cell renal cell carcinomas

The need for effective targeted therapies for renal cell carcinomas (RCCs) has fueled the interest for understanding molecular pathways involved in the oncogenesis of kidney tumors. Aiming to analyze the expression status and prognostic significance of mTOR and hypoxia-induced pathway members in patients with clear cell RCC (ccRCC), tissue microarrays were constructed from 135 primary and 41 metastatic ccRCCs. Immunoexpression levels were compared and correlated with clinicopathologic parameters and outcome. PTEN levels were significantly lower in primary and metastatic ccRCCs compared with benign tissues (P<0.001). Levels of phos-AKT, phos-S6, and 4E-binding protein-1 (4EBP1) were higher in metastatic ccRCC (P≤0.001). For phos-S6 and 4EBP1, levels were higher in primary ccRCC compared with benign tissues (P<0.001). c-MYC levels were higher in metastatic ccRCC (P<0.0001), and incremental p27 levels were observed in benign, primary ccRCC, and metastatic ccRCC (P<0.0001). HIF-1α levels were significantly higher in primary and metastatic ccRCCs compared with benign tissues (P<0.0001). In primary ccRCC, levels of all mTOR and hypoxia-induced pathway members were significantly associated with pT stage (P≤0.036), p27 levels with Fuhrman grade (P=0.031), and 4EBP1, p27, and HIF-1α levels with tumor size (P≤0.025). Tumor size, HIF-1α, and phos-S6 levels were associated with disease-specific survival (DSS) (P≤0.032) and tumor progression (P≤0.043). In conclusion, both mTOR and hypoxia-induced pathways were activated in primary and metastatic ccRCC. PTEN loss seems to be an early event during tumorigenesis. Tumor size, HIF-1α, and phos-S6 expression were found to be independent predictors of both DSS and tumor progression in primary ccRCC.

Chromosome 14q loss defines a molecular subtype of clear-cell renal cell carcinoma associated with poor prognosis

Loss of chromosome 14 has been associated with poor outcomes in clear-cell renal cell carcinoma. Expression of HIFα isoforms has been linked to distinct molecular phenotypes of clear-cell renal cell carcinoma. We hypothesized that chromosome 14 loss could lead to a decrease in HIF1α levels, as its gene (HIF1A) resides in this chromosome. We analyzed 112 archival clear-cell renal cell carcinoma tumor specimens with 250K SNP microarrays. We also evaluated expression of HIFα isoforms by qPCR and immunohistochemistry in a subset of 30 patients. Loss of chromosome 14q was associated with high stage (III-IV, P=0.001), high risk for recurrence (P=0.002, RR 2.78 (1.506-5.153)) and with decreased overall survival (P=0.030) in non-metastatic clear-cell renal cell carcinoma. HIF1α mRNA and protein expression was reduced in specimens with loss of 14q (P=0.014) whereas HIF2α was not. Gain of 8q was associated with decreased overall survival (P<0.0001). Our studies confirm an association between 14q loss and clinical outcome in non-metastatic clear-cell renal cell carcinoma patients and that 8q gain is a candidate prognostic marker for decreased overall survival and appears to further decrease survival in patients with 14q loss. We have also identified that differential expression of HIF1α is associated with 14q loss. Further exploration of 8q gain, 14q loss, MYC, HIF1A and EPAS1 (HIF2α) as molecular markers of tumor behavior and prognosis could aid in personalizing medicine for patients with clear-cell renal cell carcinoma.

Clinical genomics of renal epithelial tumors

Kidney and upper urinary tract cancers account for approximately 54,000 cases every year in the United States, and represent about 3.7% of adult malignancies, with more than 13,000 annual deaths. Classification of renal tumors is typically based on histomorphologic characteristics but, on occasion, morphologic characteristics are not sufficient. Each of the most common histologic subtypes harbors specific recurrent genetic abnormalities, such as deletion of 3p in conventional clear cell carcinoma, trisomy 7 and 17 in papillary renal cell carcinoma, multiple monosomies in chromophobe renal cell carcinoma, and a nearly diploid genome in benign oncocytomas. Knowledge of this information can provide diagnostic support and prognostic refinement in renal epithelial tumors. Identification of the specific subtype of a renal tumor is critical in guiding surveillance for recurrence and the appropriate use of targeted therapies. Cytogenomic arrays are increasingly being used as a clinical tool for genome-wide assessment of copy number and loss of heterozygosity in renal tumors. In addition, the improved understanding of the hereditary causes of renal tumors and their role in sporadic malignancies has led to the development of more effective targeted therapies. This review summarizes the genetic and genomic changes in the most common types of renal epithelial tumors and highlights the clinical implications of these aberrations.

Molecular sub-classification of renal epithelial tumors using meta-analysis of gene expression microarrays

PURPOSE

To evaluate the accuracy of the sub-classification of renal cortical neoplasms using molecular signatures.

EXPERIMENTAL DESIGN

A search of publicly available databases was performed to identify microarray datasets with multiple histologic sub-types of renal cortical neoplasms. Meta-analytic techniques were utilized to identify differentially expressed genes for each histologic subtype. The lists of genes obtained from the meta-analysis were used to create predictive signatures through the use of a pair-based method. These signatures were organized into an algorithm to sub-classify renal neoplasms. The use of these signatures according to our algorithm was validated on several independent datasets.

RESULTS

We identified three Gene Expression Omnibus datasets that fit our criteria to develop a training set. All of the datasets in our study utilized the Affymetrix platform. The final training dataset included 149 samples represented by the four most common histologic subtypes of renal cortical neoplasms: 69 clear cell, 41 papillary, 16 chromophobe, and 23 oncocytomas. When validation of our signatures was performed on external datasets, we were able to correctly classify 68 of the 72 samples (94%). The correct classification by subtype was 19/20 (95%) for clear cell, 14/14 (100%) for papillary, 17/19 (89%) for chromophobe, 18/19 (95%) for oncocytomas.

CONCLUSIONS

Through the use of meta-analytic techniques, we were able to create an algorithm that sub-classified renal neoplasms on a molecular level with 94% accuracy across multiple independent datasets. This algorithm may aid in selecting molecular therapies and may improve the accuracy of subtyping of renal cortical tumors.

Prognostic variables and nomograms for renal cell carcinoma

The term renal cell carcinoma (RCC) is used to describe a heterogeneous group of tumors that vary histologically, genetically and molecularly. Extensive research has been conducted to identify characteristics that predict outcomes among patients with RCC. In addition to histological subtype these include tumor size, patient age, mode of presentation and various hematological indices, among others. Several groups have incorporated these clinical and pathological features into nomograms which help the clinician better define individual patient prognosis and direct the optimum therapeutic approach. In the present article we review these prognostic variables and nomograms for RCC.