Tumor Size Does Not Predict Risk of Metastatic Disease or Prognosis of Small Renal Cell Carcinomas

Small renal cell carcinoma accompanied by extensive inferior vena cava tumor thrombus diagnosed by percutaneous transvenous biopsy

Introduction

Up to 10% of patients with renal cell carcinoma present with tumor thrombus in the inferior vena cava. We report that a case of small renal cell carcinoma with tumor thrombus extending above the diaphragm for which transvenous biopsy was performed for diagnosis.

Case presentation

A 79-year-old man performed computed tomography to evaluate hepatic dysfunction, which revealed intravenous tumor extending above the diaphragm and a 15-mm-sized exophytic tumor in right kidney. Imaging suggested that the renal tumor was renal cell carcinoma. As this tumor was small and exophytic, confirmation of the intravenous tumor being tumor thrombus associated with renal cell carcinoma was difficult. We simultaneously performed transvenous biopsy on the intravenous tumor and percutaneous biopsy on the renal tumor for obtaining histologic diagnoses. The final diagnosis was small renal cell carcinoma accompanied by tumor thrombus above the diaphragm.

Conclusion

Transvenous biopsy may be useful for the definitive diagnosis of inferior vena cava-tumor thrombus in cases of small renal cell carcinoma.

Predictive Factors Affecting Metastasis of Small Renal Mass and Its Prognostic Analysis

BACKGROUND

The incidence of small renal mass (SRM) increases, and the prognosis of SRM is poor once metastasized. Therefore, we conducted this study to assess the clinical and pathological characteristics of SRM to determine the risk factors that influence the metastasis and prognosis of SRM.

METHODS

A small renal mass is defined as a solid tumor mass with the largest diameter of 4 cm or less on the pathological diagnosis. The metastasis is confirmed by imaging or pathological examination. We retrospectively included 40 patients with metastatic SRM (mSRM) treated in the department of urology of Peking University Third Hospital from October 2002 to October 2020. Meanwhile, 358 patients with nonmetastatic SRM treated in our hospital from January 2015 to December 2017 were selected as controls. Clinicopathologic features were compiled.

RESULTS

Multivariate logistic regression analysis showed that age (P = .027, odds ratio [OR] = 1.037, 95% confidence interval [CI] 1.004-1.070), clinical symptoms (P < .001, OR = 4.311, 95% CI 1.922-9.672), World Health Organization/International Society of Urological Pathology (WHO/ISUP) nuclear grade 3/4 (P = .004, OR = 7.637, 95% CI 1.943-30.012; P = .004, OR = 20.523, 95% CI 2.628-160.287), and lymphatic invasion (P = .030, OR = 15.844, 95% CI 1.314-191.033) were risk factors for distant metastasis of SRM. Once metastasis occurs, the prognosis of SRM is poor. Multivariate Cox regression analysis of the prognosis of mSRM showed that age (P = .016, hazard ratio [HR] = 1.125, 95% CI 1.022-1.239), preoperative serum creatinine (P = .041, HR = 1.003, 95% CI 1.000-1.005), vascular invasion (P = .041, HR = 1.003, 95% CI 1.000-1.005), and metastasis (P < .001, HR = 24.069, 95% CI 4.549-127.356) were risk factors for overall survival (OS), and only metastasis (P < .001, HR = 9.52, 95% CI 5.43-16.7) was a risk factor for progression-free survival (PFS) of SRM.

CONCLUSIONS

SRM with advanced age, clinical symptoms, high pathological nuclear grade, and lymphatic invasion are more likely to have distant metastasis. And SRM with older age, poor preoperative basic renal function, pathological vascular invasion, and metastasis have worse OS.

Risk factors for recurrence after operation in patients with pT1a renal cell carcinoma: sub-analysis of the multi-institutional national database of the Japanese Urological Association

BACKGROUND

More patients with renal cell carcinoma are now diagnosed with the disease in its early stages. Although patients with pT1a renal cell carcinoma have a good prognosis and low recurrence rate, a few patients still experience recurrence. Herein, we evaluated the clinicopathological risk factors for postoperative recurrence of pT1aN0M0 renal cell carcinoma.

METHODS

An renal cell carcinoma survey was conducted by the Japanese Urological Association to register newly diagnosed cases of renal cell carcinoma. A total of 1418 patients diagnosed with pT1aN0M0 renal cell carcinoma who underwent surgery as the primary surgical treatment were included. We analyzed the recurrence-free survival using the Kaplan-Meier method and clinicopathological factors for recurrence using Cox proportional hazards models.

RESULTS

Among 1418 patients, 58 (4.1%) had recurrences after a median follow-up of 62.8 months. The median time to recurrence was 31.0 months. Metastases to the lungs and the bone were observed in 20 and 10 cases, respectively. Significant differences in sex, tumor size, Eastern Cooperative Oncology Group performance status, and dialysis history, preoperative hemoglobin levels, C-reactive protein levels and creatinine levels were observed between the recurrence and non-recurrence groups. Multivariate analysis identified male sex, high C-reactive protein level and tumor size ≥3 cm as independent risk factors. The 5-year recurrence-free survival of patients with 0, 1, 2 and 3 risk factors was 99.0, 97.2, 93.1 and 80.7%, respectively.

CONCLUSIONS

Male sex, tumor diameter and a high C-reactive protein level were independent recurrence risk factors for pT1a renal cell carcinoma; special attention should be paid to patients with these risk factors during postoperative follow-up.

Propensity Score-Matched Analysis of Single Fraction Robotic Radiosurgery Versus Open Partial Nephrectomy in Renal Cell Carcinoma: Oncological Outcomes

Introduction High-dose local stereotactic robotic radiosurgery (RRS) is a non-invasive alternative to surgery in renal masses and selected patients. We have, so far, limited its use to the elderly and patients at high risk from surgery. In this study, we matched patients with renal tumors who were treated with single fraction RRS to patients who underwent open partial nephrectomy (OPN). Methods Between January 2009 and December 2017, we included 571 consecutive patients undergoing OPN and 99 patients who underwent RRS in this retrospective analysis. Patients had to have a follow-up of at least six months and we were able to match 35 with a propensity score. Matching criteria were Eastern Cooperative Oncology Group (ECOG) status, age, clinical tumor, nodes, and metastases (TNM), and tumor diameter. Tumor response, renal function, survival, and adverse events were evaluated every three months until progression or death. Results Median age was 65 years for RRS (range 58-75) and 71 (range 56-76) for OPN (p=0.131). Median diameter of renal tumors was 2.8 cm (range 2.4-3.9) for RRS and 3.5 cm (2.8-4.5) for OPN, p=0.104. Median follow-up was 28.1 months (range 6.0-78.3 months). Local tumor control nine months after RRS and OPN was 98% (95% CI: 89-99%). Renal function remained stable with a median creatinine clearance (Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI)) at baseline of 76.8mlmin/1.73m2 (range 25.3-126.3) and 70.3ml/min/1.73m2 (range 18.6-127.3) at follow-up (p=0.89). Median overall survival was not reached. No difference in overall survival (OS) was seen in RRS compared to OPN (p=0.459). Conclusions Single fraction RRS is an alternative to OPN in patients unfit for surgery. Oncological and functional results are comparable to those of OPN. Further studies are needed to determine long-term results and limits of RRS in this setting and in younger patients.

Renal Tumor Size and Presence Of Synchronous Lung Metastasis At Time Of Diagnosis: Implications For Chest Imaging

OBJECTIVE

To quantify synchronous lung metastasis risk based on renal tumor size and determine a renal tumor size threshold to determine when chest imaging is warranted.

METHODS

We assessed 253,838 patients diagnosed with a renal tumor who underwent staging chest imaging between 2010-2016 within the National Cancer Database. Patients were stratified by renal tumor size in 10 mm increments, and synchronous lung metastasis risk was calculated for each category. Logistic regression analyses were used to test the relationship between renal tumor size and presence of synchronous lung metastasis after adjusting to all available covariables.

RESULTS

Overall, 14,524 out of 253,838 (5.7%) patients had evidence of synchronous lung metastasis. Median (IQR) tumor size for patients with versus without sLM was 90 mm (65 - 115) vs. 40 mm (25 - 60), respectively. The incidence of synchronous lung metastasis was low for renal tumors <40 mm, without significant change, based on tumor size. Conversely, synchronous lung metastasis increased proportionally to renal tumor size for lesions ≥40 mm. In our cohort, 47% of patients (120,386/253,838) had a renal tumor <40 mm, and 0.9% (1,135/120,386) of these had patients had synchronous lung metastasis. Only 8% (1,135/14,524) of patients with synchronous lung metastasis had a renal tumor <40 mm.

CONCLUSION

The risk of synchronous lung metastasis increased proportionally to renal tumor size; however, the risk was low for tumors <40 mm. These findings suggest that there may be minimal utility of performing screening chest imaging for patients with renal tumors <40 mm.

Comparison between small renal masses 0-2 cm vs. 2.1-4 cm in size: A population-based study

BACKGROUND

The NCCN guidelines recommend active surveillance (AS) as an option for the initial management of cT1a 0-2 cm renal lesions. However, data about comparison between renal cell carcinoma (RCC) 0-2 cm vs. 2.1-4 cm are scarce.

METHODS

Within the Surveillance, Epidemiology, and End Results database (2002-2016), 46,630 T1a N_anyM_any stage patients treated with nephrectomy were identified. Data were tabulated according to histological subtype, tumor grade (low [LG] vs. high [HG]), as well as age category and gender. Additionally, rates of synchronous metastases were quantified.

RESULTS

Overall, 69.3 vs. 74.1% clear cell, 21.4 vs. 17.6% papillary, 6.9 vs. 6.8% chromophobe, 2.0 vs. 1.1% sarcomatoid dedifferentiation, 0.2 vs. 0.2% collecting duct histological subtype were identified for respectively 0-2 cm and 2.1-4 cm RCCs. In both groups, advanced age was associated with higher rate of HG clear cell and HG papillary histological subtype. In 0-2 cm vs. 2.1-4 cm RCCs, 13.8% vs. 20.2% individuals operated on harbored HG tumors and were more prevalent in males. Lower synchronous metastases rates were recorded in 0-2 cm RCC and ranged from 0 in respectively multilocular cystic to 0.9% in HG papillary histological subtype. The highest synchronous metastases rates were recorded in sarcomatoid dedifferentiation histological subtype (13.8% and 9.7%) in both groups.

CONCLUSIONS

Relative to 2.1-4 cm RCCs, 0-2 cm RCCs harbored lower rates of HG tumors, lower rates of aggressive variant histology and lower rates of synchronous metastases. The indications and demographics of patients selected for AS may be expanded in the future to include younger and healthier patients.

Preoperative Predicting the WHO/ISUP Nuclear Grade of Clear Cell Renal Cell Carcinoma by Computed Tomography-Based Radiomics Features

Nuclear grade is important for treatment selection and prognosis in patients with clear cell renal cell carcinoma (ccRCC). This study aimed to determine the ability of preoperative four-phase multiphasic multidetector computed tomography (MDCT)-based radiomics features to predict the WHO/ISUP nuclear grade. In all 102 patients with histologically confirmed ccRCC, the training set (n = 62) and validation set (n = 40) were randomly assigned. In both datasets, patients were categorized according to the WHO/ISUP grading system into low-grade ccRCC (grades 1 and 2) and high-grade ccRCC (grades 3 and 4). The feature selection process consisted of three steps, including least absolute shrinkage and selection operator (LASSO) regression analysis, and the radiomics scores were developed using 48 radiomics features (10 in the unenhanced phase, 17 in the corticomedullary (CM) phase, 14 in the nephrographic (NP) phase, and 7 in the excretory phase). The radiomics score (Rad-Score) derived from the CM phase achieved the best predictive ability, with a sensitivity, specificity, and an area under the curve (AUC) of 90.91%, 95.00%, and 0.97 in the training set. In the validation set, the Rad-Score derived from the NP phase achieved the best predictive ability, with a sensitivity, specificity, and an AUC of 72.73%, 85.30%, and 0.84. We constructed a complex model, adding the radiomics score for each of the phases to the clinicoradiological characteristics, and found significantly better performance in the discrimination of the nuclear grades of ccRCCs in all MDCT phases. The highest AUC of 0.99 (95% CI, 0.92-1.00, p < 0.0001) was demonstrated for the CM phase. Our results showed that the MDCT radiomics features may play a role as potential imaging biomarkers to preoperatively predict the WHO/ISUP grade of ccRCCs.

Quantification of contrast-uptake as imaging biomarker for disease progression of renal cell carcinoma after tumor ablation

BACKGROUND

The prognosis of patients with renal cell carcinoma (RCC) depends greatly on the presence of extra-renal metastases.

PURPOSE

To investigate the value of total tumor volume (TTV) and enhancing tumor volume (ETV) as three-dimensional (3D) quantitative imaging biomarkers for disease aggressiveness in patients with RCC.

MATERIAL AND METHODS

Retrospective, HIPAA-compliant, IRB-approved study including 37 patients with RCC treated with image-guided thermal ablation during 2007-2015. TNM stage, RENAL Nephrometry Score, largest tumor diameter, TTV, and ETV were assessed on cross-sectional imaging at baseline and correlated with outcome measurements. The primary outcome was time-to-occurrence of extra-renal metastases and the secondary outcome was progression-free survival (PFS). Correlation was assessed using a Cox regression model and differences in outcomes were shown by Kaplan-Meier plots with significance and odds ratios (OR) calculated by Log-rank test/generalized Wilcoxon and continuity-corrected Woolf logit method.

RESULTS

Patients with a TTV or ETV > 5 cm³ were more likely to develop distant metastases compared to patients with TTV (OR 6.69, 95% confidence interval [CI] 0.33-134.4, P=0.022) or ETV (OR 8.48, 95% CI 0.42-170.1, P=0.016) < 5 cm³. Additionally, PFS was significantly worse in patients with larger ETV (P = 0.039; median PFS 51.87 months vs. 69.97 months). In contrast, stratification by median value of the established, caliper-based measurements showed no significant correlation with outcome parameters.

CONCLUSION

ETV, as surrogate of lesion vascularity, is a sensitive imaging biomarker for occurrence of extra-renal metastatic disease and PFS in patients with RCC.

Small Renal Masses With Tumor Size 0 to 2 cm: A SEER-Based Study and Validation of NCCN Guidelines

BACKGROUND

The NCCN Clinical Practice Guidelines in Oncology for Kidney Cancer recommend active surveillance as an option for initial management of T1a 0- to 2-cm renal lesions, in addition to partial nephrectomy, radical nephrectomy, and focal ablation. However, contemporary data regarding the distribution of patient and renal cell carcinoma characteristics within this special patient group are scarce.

METHODS

Within the SEER database (2002-2016), 13,364 patients with T1aNanyMany 0- to 2-cm renal lesions treated with nephrectomy were identified. Data were tabulated according to histologic subtype, Fuhrman grade (FG1-2 vs FG3-4), age category, and sex. In addition, rates of synchronous metastases were quantified.

RESULTS

Overall, clear-cell (69.3%), papillary (21.4%), chromophobe (6.9%), multilocular cystic (2.0%), sarcomatoid dedifferentiation (0.2%), and collecting-duct histologic subtypes (0.2%) were identified. Advanced age was associated with a lower rate of FG1-2 clear cell histologic subtype (70.8%-50.3%) but higher rates of FG1-2 papillary (11.1%-23.9%) and chromophobe histologic subtypes (6.2%-8.5%). Overall, 14.5% individuals harbored FG3-4 clear cell (9.8%) or FG3-4 papillary histologic subtypes (4.8%), and both were more prevalent in men. FG3-4 clear-cell and FG3-4 papillary histologic subtypes increased with age, more so in women than in men. The overall rate of synchronous metastases was 0.4% and ranged from 0 in the multilocular cystic subtype to 0.9% in the FG3-4 papillary histologic subtype, respectively, except for 13.8% in the sarcomatoid dedifferentiation histologic subtype.

CONCLUSIONS

Most T1a 0- to 2-cm renal cell carcinoma represents the low-grade clear-cell or low-grade papillary histologic subtype, with an FG3-4 minority. Even in patients with the FG3-4 histologic subtype, rates of synchronous metastases are virtually zero.

Analysis of recurrence trends according to risk groups after renal cancer nephrectomy

INTRODUCTION

Recurrence trends after renal cell cancer nephrectomy are not clearly defined.

OBJECTIVE

To evaluate recurrence trends according to recurrence risk groups (RRG).

MATERIAL AND METHOD

Retrospective analysis of 696 patients with renal cell cancer treated with nephrectomy between 1990-2010. Three RRG were defined according to the presence of anatomopathological variables (pTpN stage, nuclear grade, tumor necrosis [TN], sarcomatoid differentiation [SD], positive resection margin [RM]): -Low RG (LRG): pT1pNx-0 G1-4, pT2pNx-0 G1-2; no TN, SD and/or RM (+). -Intermediate RG (IRG): pT2pNx-0 G3-4; pT3-4pNx-0 G1-2; LRG with TN. -High RG (HRG): pT3-4pNx-0 G3-4; pT1-4pN+; IRG with TN and/or SD; LRG with SD and/or RM (+). The Kaplan-Meier method has been used to evaluate recurrence-free survival as a function of RRG. The log-rank test was used to evaluate differences between survival curves.

RESULTS

The median follow-up was 105 (IQR 63-148) months. Of the total series, 177 (25.4%) patients presented recurrence: distant 15.9%, local 4.9% and 4.6% distant and local. The recurrence rate varied according to the RRG with values of 72.9% for HRG, 16.9% for IRG and 10.2% for LRG (p=.0001). Most cases in LRG presented single organ recurrence (72.2%) (p=.006). The LRG experienced recurrence as single metastasis in 50% of cases, compared to 30% and 18.6% in IRG and HRG, respectively (p=.009). The most common sites of recurrence were lung and abdomen. Lung recurrence predominated in the HRG (72.9%) (p=.0001) and abdominal, in the LRG (83.3%) with a tendency to significance (p=.15).

CONCLUSIONS

Recurrence rates (especially bone and lung) increase with higher RG. Single organ recurrences and single metastases are more frequent in LRG.

MRI radiomics-based nomogram for individualised prediction of synchronous distant metastasis in patients with clear cell renal cell carcinoma

OBJECTIVE

To evaluate the performance of a multiparametric MRI radiomics-based nomogram for the individualised prediction of synchronous distant metastasis (SDM) in patients with clear cell renal cell carcinoma (ccRCC).

METHODS

Two-hundred and one patients (training cohort: n = 126; internal validation cohort: n = 39; external validation cohort: n = 36) with ccRCC were retrospectively enrolled between January 2013 and June 2019. In the training cohort, the optimal MRI radiomics features were selected and combined to calculate the radiomics score (Rad-score). Incorporating Rad-score and SDM-related clinicoradiologic characteristics, the radiomics-based nomogram was established by multivariable logistic regression analysis, then the performance of the nomogram (discrimination and clinical usefulness) was evaluated and validated subsequently. Moreover, the prediction efficacy for SDM in ccRCC subgroups of different sizes was also assessed.

RESULTS

Incorporating Rad-score derived from 9 optimal MR radiomics features (age, pseudocapsule and regional lymph node), the radiomics-based nomogram was capable of predicting SDM in the training cohort (area under the ROC curve (AUC) = 0.914) and validated in both the internal and external cohorts (AUC = 0.854 and 0.816, respectively) and also showed a convincing predictive power in ccRCC subgroups of different sizes (≤ 4 cm, AUC = 0.875; 4-7 cm, AUC = 0.891; 7-10 cm, 0.908; > 10 cm, AUC = 0.881). Decision curve analysis indicated that the radiomics-based nomogram is of clinical usefulness.

CONCLUSIONS

The multiparametric MRI radiomics-based nomogram could achieve precise individualised prediction of SDM in patients with ccRCC, potentially improving the management of ccRCC.

KEY POINTS

• Radiomics features derived from multiparametric magnetic resonance images showed relevant association with synchronous distant metastasis in clear cell renal cell carcinoma. • MRI radiomics-based nomogram may serve as a potential tool for the risk prediction of synchronous distant metastasis in clear cell renal cell carcinoma.

[SMALL RENAL CELL CARCINOMA PRESENTING WITH HUGE SACRALMETASTASIS: A CASE REPORT]

A 66-year-old man with buttock pain and intermittent claudication visited a nearby doctor. Magnetic resonance imaging revealed a tumor of 8 cm in diameter in his sacrum. He was referred to our hospital. Abdominal contrast enhanced computed tomography revealed a small mass of 2.5 cm in diameter on his left kidney and he was diagnosed with metastatic bone disease after needle tumor biopsy. However, needle biopsy of the renal tumor demonstrated no evidence of malignancy. As he rejected further examination, we started treatment using the tyrosine kinase inhibitor sunitinib. However, it had little effect on his sacral metastasis and he developed massive bowel bleeding twice. Extensive invasion from the sacral metastasis to the back side of the rectum was found on colonoscopy. The patient died 2 months after the introduction of sunitinib. The final diagnosis based on pathological autopsy was renal cell carcinoma with sacral metastasis.

Synchronous Metastasis Rates in T1 Renal Cell Carcinoma: A Surveillance, Epidemiology, and End Results Database-based Study

BACKGROUND

Synchronous metastasis (SM) rates in T1 renal cell carcinoma (RCC) patients relied on historical cohorts and may not take into account the favorable stage migration toward lower tumor size (TS) that occurred in more recent years.

OBJECTIVE

To investigate SM rates in T1 RCC patients according to histological subtype (HS), tumor grade (TG), and TS.

INTERVENTION

Partial nephrectomy, radical nephrectomy, focal ablation, and non-interventional management.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Within the Surveillance, Epidemiology, and End Results database (2004-2015), 60 640 stage T1 patients were identified. SM rates were tabulated and tested in multivariable logistic regression models.

RESULTS AND LIMITATIONS

According to HS, average SM rates were 0%, 0.5%, 1.1%, 1.4%, 3.7%, 21.5%, and 36.2% for multilocular cystic, chromophobe, papillary, clear cell TG 1-2, clear cell TG 3-4, collecting duct, and sarcomatoid RCC, respectively. In a multivariate logistic regression model, age, TS, HS, and TG were independent predictors of SM. Bone only was the commonest metastatic site (41.0%), followed by lung only (24.5%), liver only (3.6%), and brain only (3.8%). Of all SM patients, 72.8% harbored a single metastatic site. The major limitations of this study are lack of recurrence and metastatic progression data.

CONCLUSIONS

Within T1 RCC, it was possible to identify five metastatic risk categories according to SM rates: (1) multilocular cystic RCC (0%), (2) chromophobe RCC (0-2.0%), (3) clear cell TG 1-2 and papillary RCC, (4) clear cell TG 3-4 RCC (1.2-8.9%), and (5) sarcomatoid and collecting duct RCC (7.0-49.1%). The most frequent metastatic location is bone only, followed by lung only, and virtually all SMs are solitary.

PATIENT SUMMARY

Metastatic rate varies in T1 stage renal cell carcinoma patients according to tumor size, histology, and tumor grade.

Predicting the ISUP grade of clear cell renal cell carcinoma with multiparametric MR and multiphase CT radiomics

OBJECTIVE

To investigate externally validated magnetic resonance (MR)-based and computed tomography (CT)-based machine learning (ML) models for grading clear cell renal cell carcinoma (ccRCC).

MATERIALS AND METHODS

Patients with pathologically proven ccRCC in 2009-2018 were retrospectively included for model development and internal validation; patients from another independent institution and The Cancer Imaging Archive dataset were included for external validation. Features were extracted from T1-weighted, T2-weighted, corticomedullary-phase (CMP), and nephrographic-phase (NP) MR as well as precontrast-phase (PCP), CMP, and NP CT. CatBoost was used for ML-model investigation. The reproducibility of texture features was assessed using intraclass correlation coefficient (ICC). Accuracy (ACC) was used for ML-model performance evaluation.

RESULTS

Twenty external and 440 internal cases were included. Among 368 and 276 texture features from MR and CT, 322 and 250 features with good to excellent reproducibility (ICC ≥ 0.75) were included for ML-model development. The best MR- and CT-based ML models satisfactorily distinguished high- from low-grade ccRCCs in internal (MR-ACC = 73% and CT-ACC = 79%) and external (MR-ACC = 74% and CT-ACC = 69%) validation. Compared to single-sequence or single-phase images, the classifiers based on all-sequence MR (71% to 73% in internal and 64% to 74% in external validation) and all-phase CT (77% to 79% in internal and 61% to 69% in external validation) images had significant increases in ACC.

CONCLUSIONS

MR- and CT-based ML models are valuable noninvasive techniques for discriminating high- from low-grade ccRCCs, and multiparameter MR- and multiphase CT-based classifiers are potentially superior to those based on single-sequence or single-phase imaging.

KEY POINTS

• Both the MR- and CT-based machine learning models are reliable predictors for differentiating high- from low-grade ccRCCs. • ML models based on multiparameter MR sequences and multiphase CT images potentially outperform those based on single-sequence or single-phase images in ccRCC grading.

CT-based machine learning model to predict the Fuhrman nuclear grade of clear cell renal cell carcinoma

PURPOSE

To predict the Fuhrman grade of clear cell renal cell carcinoma (ccRCC) with a machine learning classifier based on single- or three-phase computed tomography (CT) images.

MATERIALS AND METHODS

Patients with pathologically proven ccRCC from February 1, 2009 to September 31, 2018 who were not treated were retrospectively collected for machine learning-based analysis. The texture features were extracted and ranked from precontrast phase (PCP), corticomedullary phase (CMP), nephrographic phase (NP) and three-phase CT images, and open-source gradient boosting from the decision tree library of CatBoost was used to establish a machine learning classifier to differentiate low- from high-grade ccRCC. The performances of machine learning classifiers based on features from single- and three-phase CT images were compared with each other.

RESULTS

A total of 231 patients with 232 pathologically proven ccRCC lesions were retrospectively collected. 35, 36, 41, and 22 Features were extracted and ranked from PCP, CMP, NP, and three-phase CT images, respectively. The machine learning model based on three-phase CT images [area under the ROC curve (AUC) = 0.87] achieved the best diagnostic performance for differentiating low- from high-grade ccRCC, followed by single-phase NP (AUC = 0.84), CMP (AUC = 0.80), and PCP images (AUC = 0.82).

CONCLUSION

Machine learning classifiers can be promising noninvasive techniques to differentiate low- and high-Fuhrman nuclear grade ccRCC, and classifiers based on three-phase CT images are superior to those based on features from each single phase.

Unenhanced CT Texture Analysis of Clear Cell Renal Cell Carcinomas: A Machine Learning-Based Study for Predicting Histopathologic Nuclear Grade

OBJECTIVE. The purpose of this study is to investigate the predictive performance of machine learning (ML)-based unenhanced CT texture analysis in distinguishing low (grades I and II) and high (grades III and IV) nuclear grade clear cell renal cell carcinomas (RCCs). MATERIALS AND METHODS. For this retrospective study, 81 patients with clear cell RCC (56 high and 25 low nuclear grade) were included from a public database. Using 2D manual segmentation, 744 texture features were extracted from unenhanced CT images. Dimension reduction was done in three consecutive steps: reproducibility analysis by two radiologists, collinearity analysis, and feature selection. Models were created using artificial neural network (ANN) and binary logistic regression, with and without synthetic minority oversampling technique (SMOTE), and were validated using 10-fold cross-validation. The reference standard was histopathologic nuclear grade (low vs high). RESULTS. Dimension reduction steps yielded five texture features for the ANN and six for the logistic regression algorithm. None of clinical variables was selected. ANN alone and ANN with SMOTE correctly classified 81.5% and 70.5%, respectively, of clear cell RCCs, with AUC values of 0.714 and 0.702, respectively. The logistic regression algorithm alone and with SMOTE correctly classified 75.3% and 62.5%, respectively, of the tumors, with AUC values of 0.656 and 0.666, respectively. The ANN performed better than the logistic regression (p < 0.05). No statistically significant difference was present between the model performances created with and without SMOTE (p > 0.05). CONCLUSION. ML-based unenhanced CT texture analysis using ANN can be a promising noninvasive method in predicting the nuclear grade of clear cell RCCs.

Patterns of gene expression characterize T1 and T3 clear cell renal cell carcinoma subtypes

Renal carcinoma is the 20th most common cancer worldwide. Clear cell renal cell carcinoma is the most frequent type of renal cancer. Even in patients diagnosed at an early stage, characteristics of disease progression remain heterogeneous. Up-to-date molecular classifications stratify the ccRCC samples into two clusters. We analyzed gene expression in 23 T1 or T3 ccRCC samples. Unsupervised clustering divided this group into three clusters, two of them contained pure T1 or T3 samples while one contained a mixed group. We defined a group of 36 genes that discriminate the mixed cluster. This gene set could be associated with tumor classification into a higher stage and it contained significant number of genes coding for molecular transporters, channel and transmembrane proteins. External data from TCGA used to test our findings confirmed that the expression levels of those 36 genes varied significantly between T1 and T3 tumors. In conclusion, we found a clustering pattern of gene expression, informative for heterogeneity among T1 and T3 tumors of clear cell renal cell carcinoma.

Texture analysis of small renal cell carcinomas at MDCT for predicting relevant histologic and protein biomarkers

PURPOSE

To assess CT texture features of small renal cell carcinomas (≤ 4cm) for association with key pathologic features including protein biomarkers.

METHODS

Quantitative CT texture analysis (CTTA) of small renal cancers (≤ 4cm) was performed on non-contrast and portal venous phase abdominal MDCT scans with an ROI drawn at the largest cross-sectional diameter of the tumor using commercially available software. Texture parameters including mean pixel attenuation, the standard deviation (SD) of the pixel distribution histogram, entropy, the mean of positive pixels, the skewness (i.e., asymmetry) of the pixel histogram, kurtosis (i.e., peakness) of the pixel histogram, and the percentage of positive pixels were correlated with pathologic data from surgical resection, including histology and nuclear grade, as well as microarray analysis in a subset (n = 40) including Ki67 index, CRP, and neovascularization (CD105/CD31).

RESULTS

Portal venous phase images were available in 249 patients (105 women, 144 men; mean age, 56.7 years) with tumors ≤ 4cm (mean, median, range, ± SD; 2.66, 2.60, 0.3-4.0 ± 0.85 cm). CT texture features of standard deviation, mean of the positive pixels, and entropy of the pixel histogram were significantly associated with histologic cell type (clear vs. non-clear; p < 0.001). Entropy and mean of the positive pixels also showed an association with nuclear grade, although not statistically significant. In the microarray analysis subset, kurtosis of the pixel histogram was associated with CD105/CD31 (p = 0.05). SD also showed some association with CD 105 positivity (p = 0.02) and CAIX expression (p = 0.01). Non-contrast CT images were available in 174 patients (72 women, 102 men; mean age, 57.5 years). Although the association with histology was not as strong as on the portal venous phase, in the subset of patients with microarray data, SD was found to correlate with CRP (p = 0.08), kurtosis with CRP (p = 0.004), CD105/CD31 (p = 0.002), and with Ki 67 index (p < 0.001).

CONCLUSION

CT texture features were significantly associated with important histopathologic features in small renal cancers. These non-invasive measures can be performed retrospectively and may provide useful information when determining follow-up and treatment of small renal cancers.

Metastatic risk stratification of clear cell renal cell carcinoma patients based on genomic aberrations

Prognostic markers for the definition of the individual metastatic risk in renal cell carcinoma are still missing. The aim of our study was to establish a total number of specific aberrations (TNSA) genetic score as a new prognostic test for metastatic risk evaluation. Fluorescence in situ hybridization (FISH) was performed on isolated cell nuclei of 100 ccRCCs (50 M1/50 M0) and 100 FFPE sections (second cohort, 32 M1/68 M0). For each chromosomal region (1q21.3, 7q36.3, 9p21.3p24.1, 20q11.21q13.32) cut-off values were determined by receiver-operator curve (ROC)-curve analysis. TNSA was calculated based on the dichotomized specific CNVs. The prognostic significance of CNVs was proven by Cox and logistic regression. TNSA was the best predictor of metastasis and recurrence free survival in both cohorts. We derived an algorithm for risk stratification by combining TNSA and T-category, which increased the prognostic accuracy to 87% (specificity = 86%, sensitivity = 88%). This model divides patients into two risk groups with significantly different RFS, CSS, and OS (P = 3.8×10^-5 , P = 5×10^-6 and P = 3.57×10^-8 respectively). The genetic risk model was superior to Leibovich score and was able to identify patients with metachronous metastatic spread which were incorrectly classified as "low" or "intermediate risk." We present a new tool for individual risk stratification by combining genetic alterations with clinico-pathologic parameters. Interphase FISH proves to be a dependable method for prognostic evaluation in primary tumor tissue on isolated cell nuclei as well as on FFPE sections. Especially in organ-confined tumors the genetic score seems to be an important tool to identify patients at high risk for metastatic disease.

Clear Cell Renal Cell Carcinoma: Machine Learning-Based Quantitative Computed Tomography Texture Analysis for Prediction of Fuhrman Nuclear Grade

OBJECTIVE

To evaluate the performance of quantitative computed tomography (CT) texture analysis using different machine learning (ML) classifiers for discriminating low and high nuclear grade clear cell renal cell carcinomas (cc-RCCs).

MATERIALS AND METHODS

This retrospective study included 53 patients with pathologically proven 54 cc-RCCs (31 low-grade [grade 1 or 2]; 23 high-grade [grade 3 or 4]). In one patient, two synchronous cc-RCCs were included in the analysis. Mean age was 57.5 years. Thirty-four (64.1%) patients were male and 19 were female (35.9%). Mean tumour size based on the maximum diameter was 57.4 mm (range, 16-145 mm). Forty patients underwent radical nephrectomy and 13 underwent partial nephrectomy. Following pre-processing steps, two-dimensional CT texture features were extracted using portal-phase contrast-enhanced CT. Reproducibility of texture features was assessed with the intra-class correlation coefficient (ICC). Nested cross-validation with a wrapper-based algorithm was used in feature selection and model optimisation. The ML classifiers were support vector machine (SVM), multilayer perceptron (MLP, a sort of neural network), naïve Bayes, k-nearest neighbours, and random forest. The performance of the classifiers was compared by certain metrics.

RESULTS

Among 279 texture features, 241 features with an ICC equal to or higher than 0.80 (excellent reproducibility) were included in the further feature selection process. The best model was created using SVM. The selected subset of features for SVM included five co-occurrence matrix (ICC range, 0.885-0.998), three run-length matrix (ICC range, 0.889-0.992), one gradient (ICC = 0.998), and four Haar wavelet features (ICC range, 0.941-0.997). The overall accuracy, sensitivity (for detecting high-grade cc-RCCs), specificity (for detecting high-grade cc-RCCs), and overall area under the curve of the best model were 85.1%, 91.3%, 80.6%, and 0.860, respectively.

CONCLUSIONS

The ML-based CT texture analysis can be a useful and promising non-invasive method for prediction of low and high Fuhrman nuclear grade cc-RCCs.

KEY POINTS

• Based on the percutaneous biopsy literature, ML-based CT texture analysis has a comparable predictive performance with percutaneous biopsy. • Highest predictive performance was obtained with use of the SVM. • SVM correctly classified 85.1% of cc-RCCs in terms of nuclear grade, with an AUC of 0.860.

FOXC2 and CLIP4 : a potential biomarker for synchronous metastasis of ≤7-cm clear cell renal cell carcinomas

Renal cell carcinomas (RCC) smaller than 7-cm are heterogeneous and exhibit metastatic potential in approximately 15% of cases. Although large-scale characterization of mutations in clear cell RCC (ccRCC), the most common RCC subtype, has been established, the genetic alterations related to ≤7-cm ccRCCs undergoing synchronous metastasis are poorly understood. To discover biomarkers that can be used to estimate the risk of synchronous metastasis in these ccRCC patients, we performed whole exome sequencing on the formalin-fixed paraffin-embedded (FFPE) samples of 10 ccRCC patients with ≤7-cm tumors and synchronous metastasis and expanded our study using The Cancer Genome Atlas (TCGA) ccRCC dataset (n = 201). Recurrent mutations were selected according to functional prediction and statistical significance. Mutations in three candidate genes, RELN (1 out of 10), FOXC2 (1 out of 10), and CLIP4 (2 out of 10) were found in expanded analysis using a TCGA cohort. Furthermore, siRNA-mediated target gene knockdown (FOXC2 and CLIP4) and overexpression (RELN) assays showed that FOXC2 and CLIP4 significantly increased cell migration and viability in ccRCCs. Our study demonstrated that FOXC2 and CLIP4 activity correlates to the presence of ≤7-cm ccRCCs with synchronous metastasis and may be potential molecular predictors of synchronous metastasis of ≤7-cm ccRCCs.

Worth a second look: outcomes of patients with initial finding of regular renal tissue in CT-guided renal tumor biopsies

INTRODUCTION AND OBJECTIVE

Renal tumor biopsy is recommended for histological diagnosis of radiologically indeterminate renal masses, to select patients with small-renal masses for surveillance approaches, before ablative treatments and to confirm metastatic spread of renal cell cancer (RCC), according to the EAU guidelines. We aimed to determine outcomes of patients with suspicious renal masses with initial finding of regular renal tissue in renal tumor biopsies.

METHODS

Retrospective database analysis of 101 patients undergoing CT-guided-, percutaneous renal tumor biopsies in local anesthesia.

RESULTS

In 23/101 patients, histopathologic evaluation of the biopsies showed regular renal tissue. Of these, two patients underwent simultaneous radiofrequency ablation (RFA), 2/23 underwent radical nephrectomy, despite negative biopsy because of radiological suspicious aspect. Overall, 12 patients underwent a second set of biopsies due to persistent clinical suspicion. Of these, five were diagnosed with RCC: three clear cell renal cell carcinoma (ccRCC) and two papillary renal cell carcinoma (pRCC). Benign tumours were found in two patients. A lymphoma was found in two patients. In 3/12 patients, also the second set of biopsies showed regular renal tissue.

CONCLUSION

An unsuspicious histology in CT-guided renal tumor biopsy does not preclude patients with suspicious renal masses from being diagnosed with malignancies.

Management of Small Renal Masses

With the ubiquitous use of cross-sectional abdominal imaging in recent years, the incidence of small renal masses (SRMs) has increased, and the evaluation and management of SRMs have become important clinical issues. Diagnosing a mass in the early stages theoretically allows for high rates of cure but simultaneously risks overtreatment. In the past 20 years, surgical treatment of SRMs has transitioned from radical nephrectomy for all renal tumors, regardless of size, to elective partial nephrectomy whenever technically feasible. Additionally, newer approaches, including renal mass biopsy, active surveillance for select patients, and renal mass ablation, have been increasingly used. In this chapter, we review the current evidence-based papers covering aspects of the diagnosis and management of SRMs.

Characterizing recurrent and lethal small renal masses in clear cell renal cell carcinoma using recurrent somatic mutations

INTRODUCTION

Small renal masses (SRMs) with evidence of clear cell renal cell carcinoma (ccRCC) are understudied. Current algorithms for the management of SRMs include surgical resection, ablation, and active surveillance. We sought to identify genomic biomarkers that could potentially refine the management of ccRCC in SRMs, especially in patients being evaluated for active surveillance.

METHODS

We identified patients who had SRMs (4cm or less) at time of surgery, had sequencing performed on their primary tumor and had a diagnosis of ccRCC. Patients were selected from 3 publicly available cohorts, The Cancer Genome Atlas (n = 110), University of Tokyo (n = 37), The International Cancer Genome Consortium (n = 31), and from our own institutional prospective database (n = 25). Among this cohort we analyzed mutations present in at least 5% of tumors, assessing for the enrichment of mutations and progression-free survival using the composite endpoint of recurrence or death of disease. Analysis was adjusted for multiple testing. A Cox regression model was used to assess clinical variables with significant mutations.

RESULTS

In total, 203 patients were available for analysis. Median follow-up was 43.1 months among survivors. Mutations in VHL, PBRM1, SETD2, BAP1, KDM5C, and MTOR were present in more than 5% of tumors. Twenty-three patients (11.3%) had recurrence or died of their disease. Mutations in KDM5C were associated with inferior survival from either recurrence or death from disease, adjusted P 0.033.

CONCLUSIONS

We identified mutations in SRMs in ccRCC that are associated with recurrence and lethality. The strongest association was seen in those with KDM5C mutations. Use of these genomic biomarkers may improve stratification of patients with SRMs and for those who may be appropriate for active surveillance. Prospective evaluation of these markers is needed.

Diagnostic Performance of DWI for Differentiating High- From Low-Grade Clear Cell Renal Cell Carcinoma: A Systematic Review and Meta-Analysis

OBJECTIVE

The purpose of our study was to review the diagnostic performance of DWI for differentiating high- from low-grade clear cell renal cell carcinoma (RCC).

MATERIALS AND METHODS

MEDLINE, EMBASE, and Cochrane library databases were searched up to March 15, 2017. We included diagnostic accuracy studies that used DWI for differentiating high- from low-grade clear cell RCC compared with histopathologic results of Fuhrman grade based on nephrectomy or biopsy specimens in original research articles. Two independent reviewers assessed methodologic quality using the Quality Assessment of Diagnostic Accuracy Studies 2 tool. Sensitivity and specificity of the included studies were pooled and graphically presented using a hierarchic summary ROC plot. For heterogeneity exploration, we assessed the presence of a threshold effect and performed meta-regression analyses.

RESULTS

Eight retrospective studies (394 patients with 397 clear cell RCCs) were included. Pooled sensitivity was 0.78 (95% CI, 0.68-0.85) with a specificity of 0.86 (95% CI, 0.70-0.94). A considerable threshold effect was observed with a correlation coefficient of 0.811 (95% CI, 0.248-0.964) between the sensitivity and false-positive rate. At meta-regression analysis, apparent diffusion coefficient (× 10 mm²/s) cutoff value (< 1.57 vs ≥ 1.57; p = 0.03) and location of ROI (solid portion vs whole tumor; p = 0.04) were significant factors affecting heterogeneity. Other factors with regard to patients and tumors, study, and MRI characteristics were not significant (p = 0.17-0.91).

CONCLUSION

DWI shows moderate diagnostic performance for differentiating high-from low-grade clear cell RCC. Substantial heterogeneity was observed because of a threshold effect. Further prospective studies may be needed; all included studies were retrospective.

Inherent characteristics of metachronous metastatic renal cell carcinoma in the era of targeted agents

Background

To assess the prognostic and predictive factors of time to treatment failure (TTF) and overall survival (OS), respectively, in patients with metachronous metastatic renal cell carcinoma (mRCC) who were treated with targeted agents.

Materials and Methods

We retrospectively reviewed metachronous mRCC patients, defined as individuals diagnosed with metastatic disease >3 months after initial nephrectomy, treated at an institute since 2005. Cox proportional hazard regression analysis was performed to discover the most determinant variables associated with TTF and OS.

Results

Sarcomatoid features, absence of metastasectomy, multiple site metastasis, time to metastasis <1.5 year, and increased corrected calcium were independent prognostic factors of OS. The low risk group (0-1 risk factors) did not reach the median OS, whereas the OS for the intermediate (2 risk factors) and high risk groups (3-5 risk factors) were 58.6 and 23.6 months, respectively (p<0.001). When a death event was considered the dependent factor, the area under the receiver operating characteristic curve was significantly higher than in the existing International mRCC Database Consortium (IMDC; p=0.010) and Memorial Sloan Kettering Cancer Center (MSKCC; p=0.010) risk criteria models.

Conclusion

Initial tumor size or T stage did not affect TTF or OS. Patients who could not undergo metastasectomy and rapidly developed multiple metastases with higher corrected calcium and initial tumors with sarcomatoid features were less likely to benefit from targeted therapy; thus, the new agents under development or clinical trials could be more helpful than the use of standard targeted agents.

High CXC chemokine receptor 1 level represents an independent negative prognosticator in non-metastatic clear-cell renal cell carcinoma patients

CXC chemokine receptor 1 (CXCR1) signaling has been shown as an essential molecular nexus regarding cancer cell proliferation, tumor inflammation, and angiogenesis in clear cell renal cell carcinoma (ccRCC). The aim of this study was to investigate the prognostic significance of CXCR1 in patients with non-metastatic ccRCC. Data from 446 consecutive non-metastatic ccRCC patients, operated between 2003 and 2008 at a single institution, were evaluated retrospectively. The cohort was split into a training set (n = 223) and a validation set (n = 223). CXCR1 expression was assessed by immunohistochemistry staining and its association with clinicopathologic features and prognosis were evaluated. High CXCR1 epithelial expression presented prognostic value, and indicated poor overall survival (OS) (P = 0.010 and P = 0.015, respectively) and recurrence-free survival (P = 0.011 and P = 0.019, respectively) in the training and validation sets. The incorporation of CXCR1 into the T stage and SSIGN score would help to refine individual risk stratification. Multivariate analysis identified increased epithelial CXCR1 was statistically significantly associated with a poor outcome for OS (HR [95% CI] 1.808 [1.184-2.761]; P = 0.006) and RFS (HR [95% CI] 1.570 [1.076-2.290]; P = 0.019) in all non-metastatic ccRCC patients. Predictive nomograms were generated with identified independent prognosticators to assess patient overall survival and recurrence-free survival at 3, 5 and 10 y. Furthermore, high CXCR1 expression were correlated with elevated infiltrated neutrophils and enriched MMP family gene expression. To conclude, high CXCR1 level within epithelial area represented a potential independent negative prognostic factor regarding OS and RFS in non-metastatic ccRCC patients after nephrectomy.

Severe blood loss anaemia and recurrent intussusceptions as first presentation of bowel metastatic renal cell carcinoma: A case report and review of the literature

Renal cell carcinoma (RCC) may metastasize to almost any organ, but bowel metastases are highly unusual. A 75-year-old man presented with symptoms and signs of severe anaemia due to bowel bleeding and abdominal pain due to recurrent bowel intussusception. The patient underwent surgery and was identified to have intraluminal metastases from metastatic RCC. To the best of our knowledge, few cases of metastases from RCC manifesting as synchronous intraluminal polypoid tumours have been described in the literature. The present report focused on the importance of two aspects that must be considered: The role of accurate diagnosis and of surgery treating intestinal metastases that may lead to symptom control and prolonged survival.

Thermal ablation of a confluent lesion in the porcine kidney with a clinically available MR-HIFU system

The incidence of small renal masses (SRMs) sized  <4 cm has increased over the decades (as co-findings/or due to introduction of cross sectional imaging). Currently, partial nephrectomy (PN) or watchful waiting is advised in these patients. Ultimately, 80-90% of these SRMs require surgical treatment and PN is associated with a 15% complication rate. In this aging population, with possible comorbidities and poor health condition, both PN and watchful waiting are non-ideal treatment options. This resulted in an increased need for early, non-invasive treatment strategies such as MR-guided high intensity focused ultrasound (MR-HIFU). (i) To investigate the feasibility of creating a confluent lesion in the kidney using respiratory-gated MR-HIFU under clinical conditions in a pre-clinical study and (ii) to evaluate the reproducibility of the MR-HIFU ablation strategy. Healthy pigs (n  =  10) under general anesthesia were positioned on a clinical MR-HIFU system with integrated cooling. A honeycomb pattern of seven overlapping ablation cells (4  ×  4  ×  10 mm³, 450 W, <30 s) was ablated successively in the cortex of the porcine kidney. Both MR thermometry and acoustic energy delivery were respiratory gated using a pencil beam navigator on the contralateral kidney. The non-perfused volume (NPV) was visualized after the last sonication by contrast-enhanced (CE) T ₁-weighted MR (T ₁ w) imaging. Cell viability staining was performed to visualize the extent of necrosis.

RESULTS

a median NPV of 0.62 ml was observed on CE-T ₁ w images (IQR 0.58-1.57 ml, range 0.33-2.75 ml). Cell viability staining showed a median damaged volume of 0.59 ml (IQR 0.24-1.35 ml, range 0-4.1 ml). Overlooking of the false rib, shivering of the pig, and too large depth combined with a large heat-sink effect resulted in insufficient heating in 4 cases. The NPV and necrosed volume were confluent in all cases in which an ablated volume could be observed. Our results demonstrated the feasibility of creating a confluent volume of ablated kidney cortical tissue in vivo with MR-HIFU on a clinically available system using respiratory gating and near-field cooling and showed its reproducibility.

Pattern formation in a nonlocal mathematical model for the multiple roles of the TGF-β pathway in tumour dynamics

The growth and invasion of cancer cells are very complex processes, which can be regulated by the cross-talk between various signalling pathways, or by single signalling pathways that can control multiple aspects of cell behaviour. TGF-β is one of the most investigated signalling pathways in oncology, since it can regulate multiple aspects of cell behaviour: cell proliferation and apoptosis, cell-cell adhesion and epithelial-to-mesenchimal transition via loss of cell adhesion. In this study, we use a mathematical modelling approach to investigate the complex roles of TGF-β signalling pathways on the inhibition and growth of tumours, as well as on the epithelial-to-mesenchimal transition involved in the metastasis of tumour cells. We show that the nonlocal mathematical model derived here to describe repulsive and adhesive cell-cell interactions can explain the formation of new tumour cell aggregations at positions in space that are further away from the main aggregation. Moreover, we show that the increase in cell-cell adhesion leads to fewer but larger aggregations, and the increase in TGF-β molecules - whose late-stage effect is to decrease cell adhesion - leads to many small cellular aggregations. Finally, we perform a sensitivity analysis on some parameters associated with TGF-β dynamics, and use it to investigate the relation between the tumour size and its metastatic spread.

Recurrence in Localized Renal Cell Carcinoma: a Systematic Review of Contemporary Data

PURPOSE OF REVIEW

Patients with localized renal cell carcinoma (RCC) are at risk of recurrence. The purpose of this review was to characterize the literature on recurrence rates and risk factors after diagnosis of localized RCC.

RECENT FINDINGS

Our search revealed that existing data examining the prevalence of recurrence rates predominantly originates from cohorts of patients diagnosed and treated in the 1980s to 1990s, and may therefore not be as useful for counseling for current patients today. Many nomograms including the Cindolo Recurrence Risk Formula, the University of California-Los Angeles (UCLA) Integrated Scoring System (UISS), the SSIGN score, the Kattan nomogram, and the Karakiewicz nomogram have shown value in identifying patients at higher risk for recurrence. Biomarkers and gene assays have shown promise in augmenting the predictive accuracy of some of the aforementioned predictive models, especially when multiple gene markers are used in combination. However, more work is needed in not only developing a model but also validating it in other settings prior to clinical use. Adjuvant therapy is a promising new treatment strategy for patients with high-risk disease. Importantly, too many surveillance strategies exist. This may stem from the lack of a consensus in the urological community in how to follow these patients, as well as the variable guideline recommendations. In conclusion, contemporary recurrence rates are needed. Recurrence risk prediction models should be developed based on a series of more contemporary patients, and externally validated prior to routine clinical practice. Surveillance strategies following treatment of localized RCC need to be identified and standardized. Finally, there is a trend toward personalizing surveillance regimens to more appropriately screen patients at higher risk of recurrence.

Correlation of CT imaging features and tumor size with Fuhrman grade of clear cell renal cell carcinoma

Background Identification of clinical features to determine the aggressive potential of tumors is highly warranted to stratify patients for adequate treatment. Computed tomography (CT) imaging features of clear cell renal cell carcinoma (ccRCC) may contribute to personalized risk assessment. Purpose To assess the correlation between CT imaging features and Fuhrman grade of ccRCC, and to identify the predictors of high Fuhrman grade in conjunction with tumor size. Material and Methods CT scans of 169 patients with 173 pathologically proven ccRCCs were retrospectively reviewed in consensus by two radiologists for the presence of intratumoral necrosis and intratumoral cyst and tumor size. Histologic grade was classified as either low (Fuhrman grade I or II) or high (Fuhrman grade III or IV). Statistical significance was evaluated by using univariate, multivariate regression, receiver operating characteristic (ROC) curve, and Spearman correlation analyses. Results On CT, 20 of the 173 tumors had intratumoral cysts, 60 had intratumoral necrosis, and 93 showed entirely solid tumors. The odds of high grade were higher with intratumoral necrosis and entirely solid tumor than with intratumoral cyst ( P < 0.03). Intratumoral necrosis showed a significantly high odds ratio of 25.73 for high Fuhrman grade. The ROC curve showed a threshold tumor size of 36 mm to predict high Fuhrman grade for overall tumors (area under the ROC curve, 0.70). In ccRCCs with intratumoral necrosis or cyst, tumor size did not significantly correlate with Fuhrman grade. Conclusion Intratumoral necrosis on CT was a strong and independent predictor of biologically aggressive ccRCCs, irrespective of tumor size.

Prognostic significance of modified Glasgow Prognostic Score in patients with non-metastatic clear cell renal cell carcinoma

Objective The aim of this study was to evaluate the usefulness of the modified Glasgow Prognostic Score (mGPS) as a prognostic factor in patients with non-metastatic clear cell renal cell carcinoma (RCC). Materials and methods Between June 1994 and July 2012, 469 patients with RCC underwent radical or partial nephrectomy at two hospitals. Among these patients, 65 with non-clear cell type histology and 16 with lymph-node or distant metastasis were excluded. The medical records of the remaining 388 patients were retrospectively reviewed. The mGPS was calculated using a selective combination of C-reactive protein (CRP) and albumin as previously described. The prognostic significance of various clinicopathological variables including mGPS was analyzed using univariate and multivariate analyses. Results Of the total 388 patients, 40 patients (10.3%) developed local recurrence or distant metastasis and 18 patients (4.6%) died of disease during the follow-up period. The univariate analysis identified CRP, mGPS, thrombocytosis, T stage, Fuhrman's nuclear grade and lymphovascular invasion as significant prognostic factors for recurrence-free survival (RFS) and cancer-specific survival (CSS). The multivariate analysis indicated that mGPS (p < 0.001), T stage (p = 0.024) and lymphovascular invasion (p = 0.046) were independent prognostic factors for RFS, whereas mGPS (p = 0.001) was the only independent prognostic factor for CSS. Conclusions The mGPS is an independent prognostic factor for RFS and CSS in patients with non-metastatic clear cell RCC treated with radical or partial nephrectomy. These findings suggest that mGPS should be used for predicting recurrence or survival in patients undergoing nephrectomy for non-metastatic clear cell RCC.

The role of GAGE cancer/testis antigen in metastasis: the jury is still out

Background

GAGE cancer/testis antigens are frequently expressed in various types of malignancies and represent attractive targets for immunotherapy, however their role in cancer initiation and progression has remained elusive. GAGE proteins are expressed in normal cells during early development with migratory and invasive properties and were found to be upregulated in cancer cells with metastasizing potential in a gastric cancer model.

Methods

We have addressed the direct role of GAGE proteins in supporting metastasis using an isogenic metastasis model of human cancer, consisting of 4 isogenic cell lines, which are equally tumorigenic in immunodeficient mice, but differ with their ability to generate metastases in the lungs and lymph nodes.

Results

Although GAGE proteins were strongly upregulated in the highly metastatic clone (CL16) compared to non-metastatic (NM2C5), weakly metastatic (M4A4) and moderately metastatic clones (LM3), stable downregulation of GAGE expression did not affect the ability of CL16 cells to establish primary tumors and form metastasis in the lungs of immunodeficient mice.

Conclusions

These results suggest that GAGE proteins per se do not support metastasis and that further studies are needed to clarify the contribution of GAGE proteins to the metastatic potential of different types of cancer cells.

Characterization of clear cell renal cell carcinoma by gene expression profiling

OBJECTIVES

Use global gene expression to characterize differences between high-grade and low-grade clear cell renal cell carcinoma (ccRCC) compared with normal and benign renal tissue.

METHODS

Tissue samples were collected from patients undergoing surgical resection for ccRCC. Affymetrix gene expression arrays were used to examine global gene expression patterns in high- (n = 16) and low-grade ccRCC (n = 13) as well as in samples from normal kidney (n =14) and benign kidney disease (n = 6). Differential gene expression was determined by analysis of variance with a false discovery rate of 1% and a 2-fold cutoff.

RESULTS

Comparing high-grade ccRCC with each of normal and benign kidney resulted in 1,833 and 2,208 differentially expressed genes, respectively. Of these, 930 were differentially expressed in both comparisons. In order to identify genes most related to progression of ccRCC, these differentially expressed genes were filtered to identify genes that showed a pattern of expression with a magnitude of change greater in high-grade ccRCC in the comparison to low-grade ccRCC. This resulted in the identification of genes such as TMEM45A, ceruloplasmin, and E-cadherin that were involved in cell processes of cell differentiation and response to hypoxia. Additionally changes in HIF1α and TNF signaling are highly represented by changes between high- and low-grade ccRCC.

CONCLUSIONS

Gene expression differences between high-grade and low-grade ccRCC may prove to be valuable biomarkers for advanced ccRCC. In addition, altered signaling between grades of ccRCC may provide important insight into the biology driving the progression of ccRCC and potential targets for therapy.

Transplantation of kidneys with tumors

The shortage of donors in the face of the increasing number of patients wait-listed for renal transplantation has prompted several strategies including the use of kidneys with a tumor, whether found by chance on harvesting from a deceased donor or intentionally removed from a living donor and transplanted after excision of the lesion. Current evidence suggests that a solitary well-differentiated renal cell carcinoma, Fuhrman nuclear grade I-II, less than 1 cm in diameter and resected before grafting may be considered at minimal risk of recurrence in the recipient who, however, should be informed of the possible risk and consent to receive such a graft.

Risk of metastasis for T1a renal cell carcinoma

INTRODUCTION

While active surveillance for small renal mass is gaining acceptance, controversy still continues on true metastatic potential of small renal cell carcinoma (RCC). Thus, we investigated the risks of synchronous/metachronous metastases and their potential predictors among T1a RCC patients who underwent surgical treatment.

METHODS

We reviewed data from 2114 patients who received radical or partial nephrectomy for small renal tumor (≤ 4 cm) from 1990 to 2013. For our study, patients were stratified into four different groups according to tumor size (group 1: 0-1.0 cm, group 2: 1.1-2.0 cm, group 3: 2.1-3.0 cm, group 4: 3.1-4.0 cm). Univariate and multivariate analyses were performed to analyze metastatic potentials according to tumor size and identify useful predictors of metastases.

RESULTS

Among 1913 T1a RCC patients, there were low but nonnegligible rates of metastases (group 2: 1.1 %, group 3: 3.3 %, group 4: 6.0 %, respectively). Kaplan-Meier analysis showed significant differences in metastasis-free survivals between groups (p < 0.001). A linear positive association was observed between tumor size and metastatic rate (p < 0.001). Diabetic T1a RCC patients showed significantly inferior metastasis-free survival than nondiabetic counterparts (p = 0.003). Multivariate analysis revealed that tumor size and history of diabetes mellitus were independently associated with metastasis in T1a RCC.

CONCLUSIONS

As T1a RCCs present low but nonnegligible risk of metastasis, patients with small renal mass should be counseled on such risk when offered active surveillance. Larger tumor size and history of diabetes mellitus may be associated with higher risk of metastasis in T1a RCC.

Accuracy capabilities comparisons between Karakiewicz, Kattan and Cindolo nomograms in predicting outcomes for renal cancer carcinoma: A systematic review and meta-analysis

INTRODUCTION

Several prognostic models have been proposed to predict outcomes of patients affected by renal cell carcinoma. We analyze the discriminative capabilities of Karakiewicz, Kattan and Cindolo nomograms and perform a meta-analysis to yield pooled area under the receiver operator curves (AUCs) for model comparison. The end points of interest were disease-recurrence free survival (DFS) and cancer-specific survival (CSS).

METHODS

An electronic search of the Medline and Embase was undertaken until July 2014. The AUC value, total number of patients, number of disease recurrence, and cancer-related deaths were extracted from the included references. AUCs of the models were converted to odds ratios (ORs). For the meta-analysis, ln(OR) was used for data pooling. For each nomogram, the combined OR was transformed back to a converted AUC (cAUC).

RESULTS

A total of 16 studies were identified including 26 710 patients. The derived comparison of cAUC values revealed better predictive capability of DFS for the postoperative Karakiewicz nomogram versus Kattan nomogram (p < 0.01), but not versus Cindolo (p = 0.432) and between Cindolo versus Kattan (p = 0.03). The Mantel-Haenszel derived comparison of cAUC values revealed better predictive capability for the preoperative Karakiewicz nomogram versus the Kattan nomogram (p < 0.01) and versus the Cindolo model (p < 0.01), but also between the postoperative Karakiewicz model versus the Kattan model (p < 0.01) and the Cindolo model (p < 0.01). The Kattan model showed better discriminative capability versus the Cindolo model (p < 0.01).

CONCLUSIONS

The predictive abilities of the pre- and postoperative Karakiewicz models are higher than Kattan or Cindolo in predicting DFS and CSS.

Correcting the Shrinkage Effects of Formalin Fixation and Tissue Processing for Renal Tumors: toward Standardization of Pathological Reporting of Tumor Size

Given the importance of correctly staging renal cell carcinomas, specific guidelines should be in place for tumor size measurement. While a standard means of renal tumor measurement has not been established, intuitively, tumor size should be based on fresh measurements. We sought to assess the accuracy of postfixation and microscopic measurements of renal tumor size, as compared to fresh measurements and radiographic size. Thirty-four nephrectomy cases performed by a single surgeon were prospectively measured at different time points. The study cases included 23 clear cell renal cell carcinomas, 6 papillary renal cell carcinomas, and 5 other renal tumors. Radiologic tumors were 12.1% larger in diameter than fresh tumors (P<0.01). Furthermore, fresh specimens were 4.6% larger than formalin-fixed specimens (P<0.01), and postfixation measurements were 7.1% greater than microscopic measurements (P<0.01). The overall mean percentage of shrinkage between fresh and histological specimens was 11.4% (P<0.01). Histological processing would cause a tumor stage shift from pT1b to pT1a for two tumors in this study. The shrinkage effects of formalin fixation and histological processing may result in understaging of renal cell carcinomas. The shrinkage factor should be considered when reporting tumor size.

Metastatic renal cell carcinoma mimicking diverticulitis in a patient with chronic lymphocytic leukaemia

We present an unusual case of metastatic renal cell carcinoma (RCC) mimicking diverticulitis in a 76-year-old man with a 16-year history of chronic lymphocytic leukaemia (CLL) and a 2 cm left renal mass. The patient presented with severe abdominal pain and lower gastrointestinal bleeding with anticoagulation from recent pulmonary embolism. His clinical course was troubled by recurrent hospitalisations and complications that delayed investigations and potential treatments. Radiographic findings revealed stable CLL, mild sigmoid diverticulitis and a small renal mass. Small renal masses (less than 4 cm) are considered low risk for metastasising and are, thus, often observed or ablated, rather than resected. Furthermore, gastrointestinal metastases from RCC are rare. This case adds new perspective to the unpredictable nature of RCC and how synchronous malignancies may be masked in patients with long-standing CLL.

Tumor necrosis is a strong predictor for recurrence in patients with pathological T1a renal cell carcinoma

Patients with pT1aN0M0 renal cell carcinoma (RCC) generally have good prognosis, and recurrence is rare. However, metastasis develops postoperatively in a small number of patients with pT1aN0M0 RCC. The present study was undertaken to identify predictors for recurrence in patients with pT1aN0M0 RCC. We reviewed the clinicopathological factors of 133 patients with pT1aN0M0 RCC who underwent radical or partial nephrectomy at the Department of Urology, National Defense Medical College (Saitama, Japan). Clinicopathological factors, including age, gender, tumor size, histological subtype, tumor grade, microvascular invasion, histological tumor necrosis, C-reactive protein levels and performance status were reviewed. These factors were compared between patients with and without postoperative recurrence. Recurrence-free survival (RFS) and cause-specific survival (CSS) rates were calculated using the Kaplan-Meier method. Univariate and multivariate analyses were performed to determine independent factors predicting recurrence in patients with pT1aN0M0 RCC. The 5-year RFS and CSS rates were 97.2 and 99.1%, respectively. When clinicopathological factors were compared between patients with and without recurrence, tumor size (P=0.0390) and percentage of tumor necrosis (P<0.0001) were significantly different between groups. All patients with recurrence had primary lesions ≥3 cm. By univariate analysis, tumor size (P=0.0379) and the presence of tumor necrosis (P=0.0319) were significant predictors for recurrence; tumor necrosis was also an independent predictor for recurrence (P=0.0143). In patients with pT1b tumors ≤5 cm (recurrence rate, 16.8%; n=48), the percentage of tumor necrosis was significantly higher in patients with recurrence compared with those without (P=0.0261). This suggests that tumor necrosis may be an important predictor for recurrence in small RCCs. Although recurrence is rare in pT1a RCC, the presence of tumor necrosis may be an important predictor for recurrence. Particularly, patients presenting with pT1a RCC with histological tumor necrosis should undergo careful follow-up.

Impact of Microvascular Invasion and Tumor Necrosis on the Prognosis of Korean Patients with pT1b Renal Cell Carcinoma

OBJECTIVES

To evaluate prognostic factors in pT1b renal cell carcinoma (RCC) patients for which no specific studies have been conducted on.

METHODS

The data of 270 patients diagnosed with pT1bN0M0 RCC at 2 institutions between January 1998 and June 2010 were retrospectively analyzed. Univariate and multivariate analyses using Cox proportional hazard models were used to identify pathologic and clinical factors that influenced prognosis. Five-year recurrence-free survival and cancer-specific survival were analyzed using the Kaplan-Meier method.

RESULTS

The median follow-up period was 55.5 months, and the mean patient age was 55.2 years (range: 26-80). There were 12 cancer-related deaths, and tumor recurrence was noted in 22 patients between 8 and 120 months after surgery. Sites of metastases included the lung in 13 patients, bone in 5 patients, and other sites in 4 patients. Five-year recurrence-free survival and cancer-specific survival rates were 91.2 and 93.5%, respectively. Multivariate analyses revealed that the presence of microvascular invasion and tumor necrosis independently predicted prognosis.

CONCLUSIONS

Microvascular invasion and tumor necrosis were found to be independent prognostic factors in pT1b RCC. This result will help urologists to provide patients with more accurate prognoses, and patients with confirmed microvascular invasion and tumor necrosis will require closer follow-up.

The impact of tumour size on the probability of synchronous metastasis and survival in renal cell carcinoma patients: a population-based study

BACKGROUND

The observed low metastatic potential and favorable survival of small incidentally detected renal cell carcinomas (RCCs) have been a part of the rationale for recommending partial nephrectomy as a first treatment option and active surveillance in selected patients. We examined the relationship between tumor size and the odds of synchronous metastases (SMs) (primary outcome) and disease specific survival (secondary outcome) in a nationwide RCC registry.

METHODS

Retrospective study of the 794 RCC patients diagnosed in Iceland between 1971 and 2005. Histological material and TNM staging were reviewed centrally. The presence of SM and survival were recorded. Cubic spline analysis was used to assess relationship between tumor size and probability of SM. Univariate and multivariate statistics were used to estimate prognostic factors for SM and survival.

RESULTS

The probability of SM increased in a non-linear fashion with increasing tumor size (11, 25, 35, and 50%) for patients with tumors of ≤4, 4.1-7.0, 7.1-10.0, and >10 cm, respectively. On multivariate analysis, tumor size was an independent prognostic factor for disease-specific survival (HR = 1.05, 95% CI 1.02-1.09, p < 0.001), but not for SM.

CONCLUSION

Tumor size affected the probability of disease-specific mortality but not SM, after correcting for TNM staging in multivariate analysis. This confirms the prognostic ability of the 2010 TNM staging system for renal cell cancer in the Icelandic population.

Solid renal masses: what the numbers tell us

OBJECTIVE

Solid renal masses are most often incidentally detected at imaging as small (≤ 4 cm) localized lesions. These lesions comprise a wide spectrum of benign and malignant histologic subtypes, but are largely treated with surgical resection given the limited ability of imaging to differentiate among them with consistency and high accuracy. Numerous studies have thus examined the ability of CT and MRI techniques to separate benign lesions from malignancies and to predict renal cancer histologic grade and subtype. This article synthesizes the evidence regarding renal mass characterization at CT and MRI, provides diagnostic algorithms for evidence-based practice, and highlights areas of further research needed to drive imaging-based management of renal masses.

CONCLUSION

Despite extensive study of morphologic and quantitative criteria at conventional imaging, no CT or MRI techniques can reliably distinguish solid benign tumors, such as oncocytoma and lipid-poor angiomyolipoma, from malignant renal tumors. Larger studies are required to validate recently developed techniques, such as diffusion-weighted imaging. Evidence-based practice includes MRI to assess renal lesions in situations where CT is limited and to help guide management in patients who are considered borderline surgical candidates.

Significance of chromosome 9p status in renal cell carcinoma: a systematic review and quality of the reported studies

Defining the prognosis of renal cell carcinoma (RCC) using genetic tests is an evolving area. The prognostic significance of 9p status in RCC, although described in the literature, remains underutilised in clinical practice. The study explored the causes of this translational gap. A systematic review on the significance of 9p status in RCC was performed to assess its clinical applicability and impact on clinical decision-making. Medline, Embase, and other electronic searches were made for studies reporting on 9p status in RCC. We collected data on: genetic techniques, pathological parameters, clinical outcomes, and completeness of follow-up assessment. Eleven studies reporting on 1,431 patients using different genetic techniques were included. The most commonly used genetic technique for the assessment of 9p status in RCC was fluorescence in situ hybridization. Combined genomic hybridisation (CGH), microsatellite analysis, karyotyping, and sequencing were other reported techniques. Various thresholds and cut-off values were used for the diagnosis of 9p deletion in different studies. Standardization, interobserver agreement, and consensus on the interpretation of test remained poor. The studies lacked validation and had high risk of bias and poor clinical applicability as assessed by two independent reviewers using a modified quality assessment tool. Further protocol driven studies with standardised methodology including use of appropriate positive and negative controls, assessment of interobserver variations, and evidenced based follow-up protocols are needed to clarify the role of 9p status in predicting oncological outcomes in renal cell cancer.