Growth pattern of renal cell carcinoma (RCC) in patients with delayed surgical intervention

Hibernoma in the renal sinus: A case mimicking malignancy

Introduction

Hibernomas are benign tumors of brown adipose tissue. Hibernoma in the renal sinus is extremely rare. Herein, we present the third known case of renal hibernoma.

Case presentation

A 71-year-old man reported to our department with a left kidney tumor with an average growth rate of 5 mm/year and a progressive contrast effect on computed tomography. It was diagnosed as a hibernoma following a laparoscopic radical nephrectomy.

Conclusion

We encountered a rare case of a hibernoma in the renal sinus. Development of new and accurate diagnostic methods for hibernoma, without resorting to nephrectomy, is essential.

Impact of pre- and peri-operative risk factors on length of stay and hospital readmission following minimally-invasive partial nephrectomy

Objective

We conducted an analysis of the American College of Surgeons National Surgical Quality Improvement Program database for minimally-invasive partial nephrectomy cases reported with the goal to identify pre- and peri-operative variables associated with length of stay (LOS) greater than 3 days and readmission within 30 days.

Methods

Records from 2008 to 2018 for "laparoscopy, surgical; partial nephrectomy" for prolonged LOS and readmission cohorts were compiled. Univariate analysis with Chi-square, t-tests, and multivariable logistic regression analysis with odds ratios (ORs), p-values, and 95% confidence intervals assessed statistical associations.

Results

Totally, 20 306 records for LOS greater than 3 days and 15 854 for readmission within 30 days were available. Univariate and multivariable analysis exhibited similar results. For LOS greater than 3 days, undergoing non-elective surgery (OR=5.247), transfusion of greater than four units within 72 h prior to surgery (OR=5.072), pre-operative renal failure or dialysis (OR=2.941), and poor pre-operative functional status (OR=2.540) exhibited the strongest statistically significant associations. For hospital readmission within 30 days, loss in body weight greater than 10% in 6 months prior to surgery (OR=2.227) and bleeding disorders (OR=2.081) exhibited strongest statistically significant associations.

Conclusion

Multiple pre- and peri-operative risk factors are independently associated with prolonged LOS and hospital readmission within 30 days of surgery using the American College of Surgeons National Surgical Quality Improvement Program data. Recognizing the risks factors that can potentially be improved prior to minimally-invasive partial nephrectomy is crucial to informing patient selection, optimization strategies, and patient education.

Indolent mucinous tubular and spindle cell carcinoma of the kidney: A case report and review of the literature

Mucinous tubular and spindle cell carcinoma of the kidney (MTSCC) is a rare subtype of renal cancer. It consists of tubules separated by mucus stroma and a spindle cell. Few cases have been reported; thus, the imaging features of MTSCC are not well characterized. An MTSCC in the left kidney of a 65-year-old woman was incidentally discovered during a medical checkup. A review of the patient's medical history revealed that this kidney lump had an indolent growth process. The current study presented this case and reviewed the pathological features, imaging findings and treatment options of MTSCC to strengthen the recognition of this rare renal neoplasm by radiologists.

Controversies in the diagnosis of renal cell carcinoma with tumor thrombus

Diagnosis and treatment of renal cell carcinoma with venous tumor thrombosis remains a challenge today, requiring multidisciplinary teams, mainly in tumor thrombus levels III-IV. Our objective is to present the various diagnostic techniques used and its controversies. A review of the most relevant related articles between January 2000 and August 2020 has been carried out in PubMed, EMBASE and Scielo. Continuous technological development has allowed progress in its detection, in the approximation of the histological subtype, and in the determination of tumor thrombus level. Regardless of the imaging technique used for its diagnosis (CT, MRI, TEE, ultrasound with contrast), the time elapsed until treatment is vitally important to reduce the risk of complications, some of them fatal, such as pulmonary thromboembolism.

Agent-Based Learning Model for the Obesity Paradox in RCC

A recent study on the immunotherapy treatment of renal cell carcinoma reveals better outcomes in obese patients compared to lean subjects. This enigmatic contradiction has been explained, in the context of the debated obesity paradox, as the effect produced by the cell-cell interaction network on the tumor microenvironment during the immune response. To better understand this hypothesis, we provide a computational framework for the in silico study of the tumor behavior. The starting model of the tumor, based on the cell-cell interaction network, has been described as a multiagent system, whose simulation generates the hypothesized effects on the tumor microenvironment. The medical needs in the immunotherapy design meet the capabilities of a multiagent simulator to reproduce the dynamics of the cell-cell interaction network, meaning a reaction to environmental changes introduced through the experimental data.

Natural history and growth kinetics of clear cell renal cell carcinoma in sporadic and von Hippel-Lindau disease

Background

To evaluate and compare the natural history and growth kinetics of sporadic clear cell renal cell carcinoma (ccRCC) with those of ccRCC in von Hippel-Lindau disease (VHL).

Methods

Sixty patients in the sporadic group with 61 tumors and 15 patients in the VHL group with 30 tumors whom all underwent delayed surgery after at least 12 months of active surveillance (AS) were enrolled to conduct a retrospective cohort study. The growth rate was calculated, and the growth kinetics between the sporadic and VHL groups were compared. The patient and tumor characteristics were reviewed, and their correlation with growth rate was analyzed.

Results

The mean growth rate of sporadic ccRCC was 0.91 cm/year (ranging from 0–4.74 cm/year) and that of VHL ccRCC was 0.47 cm/year (ranging from 0.04–1.89 cm/year). The growth rate of sporadic ccRCC showed a tendency of being faster than that of VHL ccRCC but did not reach statistical significance (P=0.07). The factors affecting the growth rate were different between the two groups. For VHL ccRCC, the only factor that correlated with growth rate was initial tumor diameter (P<0.001), but for sporadic ccRCC, the only factor was pathological nuclear grade (P<0.001).

Conclusions

The growth rate of VHL-associated ccRCC might be slower than that of sporadic ccRCC. Furthermore, we identified a disparity in growth kinetics between sporadic and VHL-associated ccRCC.

Computed Tomography-Based Radiomics Model for Predicting the WHO/ISUP Grade of Clear Cell Renal Cell Carcinoma Preoperatively: A Multicenter Study

Purpose

To examine the ability of computed tomography radiomic features in multivariate analysis and construct radiomic model for identification of the the WHO/ISUP pathological grade of clear cell renal cell carcinoma (ccRCC).

Methods

This was a retrospective study using data of four hospitals from January 2018 to August 2019. There were 197 patients with a definitive diagnosis of ccRCC by post-surgery pathology or biopsy. These subjects were divided into the training set (n = 122) and the independent external validation set (n = 75). Two phases of Enhanced CT images (corticomedullary phase, nephrographic phase) of ccRCC were used for whole tumor Volume of interest (VOI) plots. The IBEX radiomic software package in Matlab was used to extract the radiomic features of whole tumor VOI images. Next, the Mann-Whitney U test and minimum redundancy-maximum relevance algorithm(mRMR) was used for feature dimensionality reduction. Next, logistic regression combined with Akaike information criterion was used to select the best prediction model. The performance of the prediction model was assessed in the independent external validation cohorts. Receiver Operating Characteristic curve (ROC) was used to evaluate the discrimination of ccRCC in the training and independent external validation sets.

Results

The logistic regression prediction model constructed with seven radiomic features showed the best performance in identification for WHO/ISUP pathological grades. The Area Under Curve (AUC) of the training set was 0.89, the sensitivity comes to 0.85 and specificity was 0.84. In the independent external validation set, the AUC of the prediction model was 0.81, the sensitivity comes to 0.58, and specificity was 0.95.

Conclusion

A radiological model constructed from CT radiomic features can effectively predict the WHO/ISUP pathological grade of CCRCC tumors and has a certain clinical generalization ability, which provides an effective value for patient prognosis and treatment.

Available active surveillance follow-up protocols for small renal mass: a systematic review

PURPOSE

To evaluate follow-up strategies for active surveillance of renal masses and to assess contemporary data.

METHODS

We performed a comprehensive search of electronic databases (Embase, Medline, and Cochrane). A systematic review of the follow-up protocols was carried out. A total of 20 studies were included.

RESULT

Our analysis highlights that most of the series used different protocols of follow-up without consistent differences in the outcomes. Most common protocol consisted in imaging and clinical evaluation at 3, 6, and 12 months and yearly thereafter. Median length of follow-up was 42 months (range 1-137). Mean age was 74 years (range 67-83). Of 2243 patients 223 (10%) died during the follow-up and 19 patients died of kidney cancer (0.8%). The growth rate was the most used parameter to evaluate disease progression eventually triggering delayed intervention. Maximal axial diameter was the most common method to evaluate growth rate. CT scan is the most used, probably because it is usually more precise than kidney ultrasound and more accessible than MRI. Performing chest X-ray at every check does not seem to alter the clinical outcome during AS.

CONCLUSION

The minimal cancer-specific mortality does not seem to correlate with the follow-up scheme. Outside of growth rate and initial size, imaging features to predict outcome of RCC during AS are limited. Active surveillance of SRM is a well-established treatment option. However, standardized follow-up protocols are lacking. Prospective, randomized, trials to evaluate the best follow-up strategies are pending.

Enhanced computed tomography radiomics-based machine-learning methods for predicting the Fuhrman grades of renal clear cell carcinoma

OBJECTIVE

To develop and test an optimal machine learning model based on the enhanced computed tomography (CT) to preoperatively predict pathological grade of clear cell renal cell carcinoma (ccRCC).

METHODS

A retrospective analysis of 53 pathologically confirmed cases of ccRCC was performed and 25 consecutive ccRCC cases were selected as a prospective testing set. All patients underwent routine preoperative abdominal CT plain and enhanced scans. Renal tumor lesions were segmented on arterial phase images and 396 radiomics features were extracted. In the training set, seven discrimination classifiers for high- and low-grade ccRCCs were constructed based on seven different machine learning models, respectively, and their performance and stability for predicting ccRCC grades were evaluated through receiver operating characteristic (ROC) analysis and cross-validation. Prediction accuracy and area under ROC curve were used as evaluation indices. Finally, the diagnostic efficacy of the optimal model was verified in the testing set.

RESULTS

The accuracies and AUC values achieved by support vector machine with radial basis function kernel (svmRadial), random forest and naïve Bayesian models were 0.860±0.158 and 0.919±0.118, 0.840±0.160 and 0.915±0.138, 0.839±0.147 and 0.921±0.133, respectively, which showed high predictive performance, whereas K-nearest neighborhood model yielded lower accuracy of 0.720±0.188 and lower AUC value of 0.810±0.150. Additionally, svmRadial had smallest relative standard deviation (RSD, 0.13 for AUC, 0.17 for accuracy), which indicates higher stability.

CONCLUSION

svmRadial performs best in predicting pathological grades of ccRCC using radiomics features computed from the preoperative CT images, and thus may have high clinical potential in guiding preoperative decision.

Routes to diagnosis and missed opportunities in the detection of renal cancer

AIM

To determine the proportion of renal cancers for which incidental detection was the route to diagnosis, the characteristics of tumours identified in this way, and the frequency with which opportunities to make this diagnosis were missed.

MATERIALS AND METHODS

Consecutive patients with renal cancers treated at Royal Cornwall Hospitals NHS Trust (April 2011 and July 2018 inclusive) were identified from the Trust's cancer registry database, and a retrospective review of the imaging and electronic case notes was undertaken. Mann-Whitney U-tests for comparison of patient age and tumour size at diagnosis, and chi-squared tests for comparing cell type distribution and grade were performed. Logistic regression was then used to identify the characteristics of patients in whom a renal tumour was missed initially.

RESULTS

Of 327 patients, 194 (63%) presented incidentally, and 133 (37%) symptomatically. Incidentally detected cancers were found in younger patients, (median of 65 years versus 69 p=0.01) and were smaller at presentation (median of 5.5 versus 7.2 cm, p<0.00001). Thirty-six different reporters missed opportunities to diagnose renal cancer in 50 (16%) patients on 78 occasions, 28 lesions (35%) being missed more than once. Thirty were imaged incompletely; four were visible only on a single image and three on a scout view at magnetic resonance imaging.

CONCLUSION

The commonest route to diagnosis of renal cancer is by incidental detection of a mass. In 16% of patients in whom renal cancer is diagnosed, there is at least one prior examination on which the lesion is visible at an earlier date. The clinical impact of these missed diagnostic opportunities remains uncertain.

Renal tumor growth rate in patients with previously normal CT scan: Analysis of the initial stage of growth

OBJECTIVE

Most of the studies regarding natural history of renal masses are based on active surveillance series and suggest that the renal masses have a slow growth rate. Nevertheless, only a few studies report the time between a normal computed tomography (CT) scan to the first detection of a tumor. We aimed to analyze the growth rate in newly diagnosed kidney tumors.

MATERIAL AND METHODS

We analyzed patients with enhancing renal masses that developed after a normal CT scan, which was performed at most 12 months earlier. Variables examined included patient age, gender, tumor size, volume, tumor linear growth rate (LGR). All cases were surgically treated. Mann-Whitney U test was used to compare variables. A p<0.05 was considered as statistically significant.

RESULTS

We found 31 patients with 33 lesions. Male to female ratio was 1.58 (19/12). The average age was 59.2 years (standard deviation [SD]±12.1), and the mean tumor size was 4.27 cm (SD±4.3). Tumor LGR was 0.87 cm/month (range: 0.28-1.66) and presumed to be 10.4 cm at 1 year (range: 3.36-19.9). Tumor LGR for time detection at <6 month or ≥6 months were 1.1 cm/month and 0.68 cm/month (range: 0.27-1.08 and 0.88-1.76, respectively; p=0.0004), respectively. Tumor LGRs for low- and high-grade tumors were 0.89 cm/month and 0.83 cm/month (p=0.65), respectively. Median volume was 36.1 cm³ (range: 2.61-143.7), and for low and high grade the median volumes were 27.9 cm³ and 47.6 cm³, respectively (p=0.54). Malignant pathology was present in 93.9 % (31 of 33) of masses (lesions).

CONCLUSION

We found differences in tumor LGR in tumors detected before and after 6 months. We did not find any correlation between tumor growth rate and Fuhrman grade system, gender, histology, or age. We found the highest LGR published up to date.

CT texture analysis: a potential tool for predicting the Fuhrman grade of clear-cell renal carcinoma

BACKGROUND

The purpose of this study was to analyze the image heterogeneity of clear-cell renal-cell carcinoma (ccRCC) by computer tomography texture analysis and to provide new objective quantitative imaging parameters for the pre-operative prediction of Fuhrman-grade ccRCC.

METHODS

A retrospective analysis of 131 cases of ccRCCs was performed by manually depicting tumor areas. Then, histogram-based texture parameters were calculated. The texture-feature values between Fuhrman low- (Grade I-II) and high-grade (Grade III-IV) ccRCCs were compared by two independent sample t-tests (False Discovery Rate correction), and receiver operating characteristic curve (ROC) was used to evaluate the efficacy of using texture features to predict Fuhrman high- and low-grade ccRCCs.

RESULTS

There were no statistical differences for any texture parameters without filtering (p > 0.05). There was a statistically significant difference between the entropy (fine) of the corticomedullary phase and the entropy (fine and coarse) of the nephrographic phase after Laplace of Gaussian filtering. The area under the ROC of the entropy was between 0.74 and 0.83.

CONCLUSIONS

Computer tomography texture features can predict the Fuhrman grading of ccRCC pre-operatively, with entropy being the most important imaging marker for clinical application.

Imaging Protocols for Active Surveillance in Renal Cell Carcinoma

PURPOSE OF REVIEW

To review the growth kinetics of small renal masses and available imaging modalities for mass characterization and surveillance, highlight current organizational recommendations for the active surveillance of small renal masses, and discuss the most recently reported oncological outcomes of patients as they relate to various surveillance imaging protocols and progression to delayed intervention.

RECENT FINDINGS

Overall, organizational guideline recommendations are broad and lack specifics regarding timing and modality for follow-up imaging of small renal masses. Additionally, despite general consensus in the literature about certain criteria to trigger delayed intervention, there exist no formal guidelines. Active surveillance of small renal masses is an acceptable management strategy for patients with prohibitive surgical risk; however, standardized imaging protocols for surveillance are lacking, as are randomized, prospective trials to evaluate the ideal follow-up protocol.

Role of Active Surveillance for Localized Small Renal Masses

CONTEXT

Stage migration of organ-confined renal masses is occurring as a result of incidental diagnosis, especially in the elderly. Active surveillance (AS) is gaining clinical traction as a treatment alternative to surgery and focal therapy.

OBJECTIVE

To assess contemporary data and evaluate AS risk trade-offs in the treatment of organ-confined kidney cancer.

EVIDENCE ACQUISITION

A comprehensive search of the Embase, Medline and Cochrane databases was carried out. A systematic review of the role of AS for organ-confined renal masses was performed. A total of 28 studies were included in the systematic review.

EVIDENCE SYNTHESIS

The median linear tumor growth rate for clinically localized renal masses (CLRMs) was 0.37cm/yr (interquartile range 0.15-0.7), with 0.22cm/yr in the cT1a subgroup and 0.45cm/yr in the cT1b--2 subgroup. The metastatic progression rate was 1-6% and was similar for cT1a (1-6%) and cT1b (0-5%); other-cause mortality for patients with CLRMs was 0-45% (1-25% for cT1a vs 11-13% for cT1b-2); cancer-specific mortality ranged between 0% and 18%. According to the 2011 Oxford scale, AS as a treatment option for CLRMs remains supported by level 3 evidence.

CONCLUSIONS

Although no randomized clinical data are available, current data support oncologic safety for AS in the management of CLRMs, particularly for small renal masses and among elderly and/or comorbid patients.

PATIENT SUMMARY

In this review we looked at the outcomes for patients with small kidney masses managed with surveillance. We found that surveillance is a safe initial option for tumors of less than 2cm, especially in elderly and sick patients.

Multiple growth periods predict unfavourable pathology in patients with small renal masses

OBJECTIVE

To use the number of positive growth periods as a characterization of the growth of small renal masses in order to determine potential predictors of malignancy.

PATIENTS AND METHODS

Patients who underwent axial imaging at multiple time points prior to surgical resection for a small renal mass were queried. Patients were categorized based on their pathological tumour grade and stage: favourable (benign, chromophobe and low-grade pT1-2 renal cell carcinoma [RCC]) vs unfavourable (high-grade of any stage and low-grade pT3-4 RCC). A positive growth period was counted each time the difference in greatest tumour diameters between two images was positive. The Cochran-Armitage trend test and Somers' D association were used to determine if the number of positive growth periods was correlated with unfavourable pathology.

RESULTS

Of the 124 patients, 86 (69.4%) had favourable pathology and 38 (30.6%) had unfavourable pathology. Those who had favourable pathology were younger than those who had unfavourable pathology: median (interquartile range [IQR]) 61.0 (52.2-66.0) vs 68.5 (61.5-77.0); P < 0.001. The overall growth rate was higher in the unfavourable group, but was not statistically significant: mean (sd) 0.7 (1.7) vs 1.6 (2.8) cm/year; P = 0.07. There was a significant trend difference in the number of positive growth periods between favourability groups (P = 0.02). An association between increased number of positive growth periods and unfavourable pathology was observed: 0.15 (95% confidence interval 0.02, 0.29). The ratios of favourable to unfavourable pathology were 1.8, 1.0, 0.66, 0.59 and 0 as the number of positive growth periods increased from 0 to 4, respectively.

CONCLUSION

While overall growth rate was not predictive of pathology favourability, there was a positive association between the number of positive growth periods and unfavourable pathology. The number of positive growth periods may be a potential parameter for malignant potential in patients undergoing active surveillance for small renal masses.

Growth Kinetics of Small Renal Masses on Active Surveillance: Variability and Results from the DISSRM Registry

PURPOSE

Active surveillance is emerging as a safe and effective strategy for the management of small renal masses (4 cm or less). We characterized the growth rate and its pertinence to clinical outcomes in a prospective multi-institutional study of patients with small renal masses.

MATERIALS AND METHODS

Since 2009, the DISSRM (Delayed Intervention and Surveillance for Small Renal Masses) prospective, multi-institutional registry of patients with small renal masses has enrolled patients who elect primary intervention or active surveillance. Patients who elect active surveillance received regularly scheduled imaging and those with 3 or more followup images were included in the current study to evaluate growth rates.

RESULTS

We evaluated 318 patients who elected active surveillance, of whom 271 (85.2%) had 3 or more followup images available with a median imaging followup of 1.83 years. The overall mean ± SD small renal mass growth rate was 0.09 ± 1.51 cm per year (median 0.09) with no variables demonstrating statistically significant associations. The growth rate and variability decreased with longer followup (0.54 and 0.07 cm per year at less than 6 months and greater than 1 year, respectively). No patients had metastatic disease or died of kidney cancer. No statistically significant difference was noted in the growth rate in patients with biopsy demonstrated renal cell carcinoma or in those who died.

CONCLUSIONS

Small renal mass growth kinetics are highly variable early on active surveillance with growth rates and variability decreasing with time. Early in active surveillance, especially during the initial 6 to 12 months, the growth rate is variable and does not reliably predict death or adverse pathological features in the patient subset with available pathology findings. An elevated growth rate may indicate the need for further assessment with imaging or consideration of biopsy prior to progressing to treatment. Additional followup will inform the best clinical pathway for elevated growth rates.

Active Surveillance of Nonfatty Renal Masses in Patients With Lymphangioleiomyomatosis: Use of CT Features and Patterns of Growth to Differentiate Angiomyolipoma From Renal Cancer

OBJECTIVE

The objective of this study was to report our experience with active surveillance of nonfatty renal masses in a large cohort of patients with lymphangioleiomyomatosis (LAM), correlate their CT features and patterns of growth with histopathology results, and provide guidelines for management.

SUBJECTS AND METHODS

Yearly CT examinations were performed of 367 women (age range, 21-75 years; mean age, 47 years). For the 31 patients with 37 nonfatty renal masses that were biopsied, excised, or followed for ≥ 5 years, CT enhancement characteristics and patterns of growth were compared with the histopathology results.

RESULTS

Four of 37 nonfatty renal masses were biopsied without follow-up CT examinations: Two were heterogeneous renal cell carcinomas (RCCs), one was a heterogeneous nonfatty angiomyolipoma (AML), and one was homogeneous nonfatty AML. In the remaining 33 nonfatty renal masses with multiple follow-up CT examinations, two growth patterns were identified. Four showed a continuous increase in size of > 0.5 cm/y in some years, and all four in this first group were heterogeneous and were biopsy-proven RCC. The second group was composed of the remaining 29 masses. These 29 masses showed yearly no change, increase, or decrease in diameter. Eight were heterogeneous, and 21 were homogeneous. Of the masses showing a yearly increase, the increase was < 0.5 cm/y in all except one. In the one exception, the increase followed a decrease. Nine of the 29 masses were biopsied, and all nine were nonfatty renal masses (five homogeneous, four heterogeneous).

CONCLUSION

Our data provide further evidence in a large prospective study with longterm follow-up that active surveillance is an appropriate strategy in the management of nonfatty renal masses in patients with LAM. Our analysis of the growth patterns reveals duration of growth in addition to growth rate as criteria for biopsy or excision. Biopsy should be reserved for nonfatty renal masses that show sustained growth or growth > 0.5 cm/y during follow-up.

Active Surveillance for Small Renal Masses: When Less is More

CONTEXT

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

OBJECTIVE

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

EVIDENCE ACQUISITION

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

EVIDENCE SYNTHESIS

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

CONCLUSIONS

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

PATIENT SUMMARY

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

Active Surveillance for the Small Renal Mass: Growth Kinetics and Oncologic Outcomes

Active surveillance for small renal masses (SRMs) is an accepted management strategy for patients with prohibitive surgical risk. Emerging prospectively collected data support the concept that a period of initial active surveillance in an adherent patient population with well-defined criteria for delayed intervention is safe. This article summarizes the literature describing growth kinetics of SRMs managed initially with observation and oncologic outcomes for patients managed with active surveillance. Existing clinical tools to determine and contextualize competing risks to mortality are explored. Finally, current prospective clinical trials with defined eligibility criteria, surveillance schema, and triggers for delayed intervention are highlighted.

Natural history of small renal masses

Objective:

To review the natural history and growth kinetics of small renal masses (SRMs).

Data Sources:

The literature concerning natural history and growth kinetics of SRMs was collected from PubMed published from 1990 to 2014.

Study Selection:

We included all the relevant articles on the active surveillance (AS) or delayed treatment for SRMs in English, with no limitation of study design.

Results:

SRMs under AS have a slow growth potential in general. The mean linear growth rate is 0.33 cm/year, the mean volumetric growth rate is 9.48 cm³/year. The rate of metastasis during AS is below 2%. Some factors are associated with the growth rate of SRMs, including tumor grade, histological subtype, initial tumor size, age, radiographic characteristics, and molecular markers. No definite predictor of growth rate of SRMs is defined at present. SRMs with high tumor grade and the subtype of clear cell renal cell carcinoma may have aggressive growth potential.

Conclusions:

AS is a reasonable choice for elderly patients with SRMs, who are at high risk from surgery. Progression during observation is the biggest concern while performing AS. There is no definite predictor of progression for SRMs under AS. Percutaneous renal biopsy providing immunohistological and genic biomarkers may improve the understanding of natural history of SRMs.

The growth rate of "clinically significant" renal cancer

Surveillance studies of enhancing renal masses report on a mean tumor growth rate of about 0.3 cm/year. In most of these studies however, only small tumors in elderly patients were followed. In the current report, we attempt to evaluate the growth rate of “clinically significant” renal carcinomas defined as tumors that were treated immediately upon diagnosis. 46 patients (mean age 64 years SD 11 years) were treated for renal carcinoma. All had a cross-sectional imaging studies performed 6–60 months prior to diagnosis of kidney cancer demonstrating no tumor. Tumor growth rate was calculated by dividing tumor’s largest diameter by the time interval between the normal kidney imaging and diagnosis of renal cancer. Mean tumor diameter was 4.5 cm (SD 2.4 cm). Mean time period from the normal imaging to diagnosis of renal cancer was 33.6 months (SD 18 months). According to the proposed model, the average growth rate of “clinically significant” renal carcinomas was 2.13 cm/year (SD 1.45, range 0.2–6.5 cm/year). Tumor growth rate correlated inversely with patient’s age (p = 0.007). Patient gender or Fuhrman’s grade did not correlate however. The growth rate of “clinically significant” renal cancer appears to be higher than the rate reported in surveillance trials. Renal tumors tend to grow faster in young patients. As such, variable growth rate should be taken into account when considering active surveillance in young patients and when designing trials for evaluation of anti-cancer agents.

Growth Pattern of Clear Cell Renal Cell Carcinoma in Patients with Delayed Surgical Intervention: Fast Growth Rate Correlates with High Grade and May Result in Poor Prognosis

Objectives. Previous studies revealed an unclear correlation between the growth rate of renal cell carcinoma (RCC) and tumor grade and did not focus on certain histological subtype. This report investigated the correlation between the growth rate and tumor grade in clear cell RCC (ccRCC). Methods. We reviewed 60 patients with 61 ccRCC confirmed by delayed surgeries after at least 12 months of active surveillance. The linear growth rate (LGR), volumetric growth rate (VGR), and volume doubling time (VDT) were calculated, and their correlations with clinicopathologic characteristics were analyzed. Results. The mean LGR, VGR, and VDT were 0.86 (range 0–4.74) cm/year, 20.96 (range 0.31–211.93) cm³/year, and 667 (range 33–3321) days, respectively. ccRCCs with high grade had greater LGR (P < 0.001) and VGR (P = 0.001) and lower VDT (P = 0.017) than ccRCCs with low grade. Grade (OR = 5.185, P = 0.004) was the only independent risk factor of LGR >0.5 cm/year, and grade (OR = 3.006, P = 0.046) and initial size (OR = 0.392, P = 0.004) were independent risk factors of VDT <1 year. Five patients developed metastasis after surgery with LGR >0.5 cm/yr altogether; of them, four had cancer-related death by the last follow-up. Conclusions. Fast growth rate of ccRCC is significantly correlated with high tumor grade and may result in poor prognosis, especially for those with LGR >0.5 cm/yr.

Clinical effectiveness of (18)f-fluorodeoxyglucose positron emission tomography/computed tomography in management of renal cell carcinoma: a single institution experience

Positron emission tomography (PET) is currently the most advanced technique of metabolic imaging available for tumor diagnosis and follow-up. The aim of this study was to examine the versatility and accuracy of fluorodeoxyglucose (FDG) PET/computed tomography (CT) in the metastasis detection of renal cell carcinoma (RCC). We also compared our findings to other similar studies from the literature. This is the biggest study so far to examine the sensitivity and specificity of FDG PET/CT in the management of RCC. A retrospective review was carried out on all the FDG PET/CT studies done from January 1999 to January 2014 at our institution. Biopsy results were considered the gold standard. For our patients (n = 315) with biopsy results, FDG PET/CT studies exhibited 100% sensitivity, 100% specificity. Our results were better than results achieved by other studies. The use of FDG PET/CT in restaging and metastasis detection of RCC has many advantages, in addition to high accuracy. This imaging technique has great potential in influencing treatment decisions. We recommend the incorporation of FDG PET/CT in routine standard protocols for RCC.

Optimal follow-up intervals in active surveillance of renal masses in patients with von Hippel-Lindau disease

OBJECTIVES

To estimate an optimal follow-up (FU) interval for von Hippel-Lindau (VHL) patients with renal masses (RMs) by determining tumour growth rates from growth curves.

METHODS

Thirty lesions (47.6%) were classified as solid tumours (STs) and 33 (52.4%) as complex cysts (CCs). Variations in lesion volume over time were analyzed. For 53 lesions, we calculated the growth rate during the period when the volume of the lesion changed most rapidly, and called this the fast growth rate (FGR).

RESULTS

The STs initially grew fast, followed by a period of slower growth. The CCs varied in volume over time, associated with variable amounts of their fluid component. The FGR correlated better with the latest volume for STs (r = 0.905) than for CCs (r = 0.780). An optimal FU interval between 3 and 12 months was derived by combining the FGR calculated from the curve with the latest volume measured.

CONCLUSIONS

Analyzing growth curves and related kinetic parameters for RMs in VHL patients could be useful with a view to optimizing the subsequent FU interval and improving the active surveillance program.

KEY POINTS

• Measuring volume changes over time enables tumour growth curves to be charted. • Renal solid tumours increase in volume with a typical sigmoidal curve. • Complex cysts may increase and decrease in volume spontaneously over time. • The fast growth rate of solid tumours correlates with their latest volume. • The fast growth rate can orient the scheduling of subsequent follow-ups.

Prediction of nuclear grade of clear cell renal cell carcinoma with MRI: intratumoral susceptibility signal intensity versus necrosis

BACKGROUND

End-stage renal disease and dialysis patients have a higher incidence of renal cell carcinoma (RCC) than the general population. Preoperatively evaluating the biological behavior of RCC plays an important role in treatment decision-making. Susceptibility-weighted imaging (SWI) can visualize the distribution of microvenous structures and hemorrhage without contrast materials.

PURPOSE

To evaluate the feasibility of SWI in grading clear cell RCCs (CRCC) and compare the ability of SWI and necrosis for grading CRCCs.

MATERIAL AND METHODS

Retrospective reviews of 35 patients with pathologically-proven CRCCs were performed. All patients underwent both conventional magnetic resonance imaging (MRI) and SWI examinations. The morphology of the intratumoral susceptibility signal intensities (ITSS) was classified into hemorrhage and microvessels. The differences of ITSSs on SWI and necrosis between low- and high-grade CRCCs were assessed. The diagnostic values of ITSSs and necrosis in differentiating low- from high-grade CRCCs were compared by receiver-operating characteristics.

RESULTS

ITSSs were seen in 31 of 35 patients. No ITSSs were seen in four patients with low-grade CRCCs. Mean scores of ITSSs on SWI were significantly lower for low-grade CRCCs (1.24 ± 0.72) than that for the high-grade CRCCs (2.70 ± 0.48). No significant necrosis was seen in 10 patients with low-grade CRCCs. There was a significant difference of the presence of intratumoral necrosis between low- and high-grade CRCCs. Sensitivity, specificity, positive (PPV) and negative predictive values (NPV) were for ITSSs: 70%, 100%, 100%, and 89.3%, respectively; for necrosis: 100%, 40%, 40%, and 100%.

CONCLUSION

SWI can evaluate ITSSs without contrast materials and can be an alternative to grading CRCCs preoperatively for some special patients.

Assessment of intratumoral micromorphology for patients with clear cell renal cell carcinoma using susceptibility-weighted imaging

Background

Multiple treatment options exist for the management of renal cell carcinomas. Preoperative evaluation of clear cell renal cell carcinoma (CRCC) grades is important for deciding upon the appropriate method of therapy. We hypothesize that susceptibility weighted imaging (SWI) is sensitive enough to detect intratumoral microvessles and microbleeding in renal cell carcinoma, which can be used to grade CRCC.

Material and Methods

Retrospective reviews of 37 patients with pathologically proven CRCCs were evaluated. All patients underwent SWI examinations. The characteristics of intratumoral susceptibility signal intensity (ITSS) includes the likelihood of the presence of ITSS, morphology of ITSS, dominant structure of ITSS and ratio of ITSS area to tumor area, which were all assessed on SWI. The results were compared using the nonparametric Mann-Whitney test.

Results

ITSS was seen in all patients except 4 patients with low-grade CRCCs. There was no significant difference between low and high-grade CRCCs when looking at the likelihood of the presence of ITSS. There was a significant difference in the mean score of dominant structures between low and high-grade CRCCs. Specifically, more dominant vascular structures and less hemorrhage were seen in low-grade tumors (2.15±1.05) compared to high-grade tumors (1.27±0.47) (P<0.005). The ratio of ITSS area to tumor area was also significantly higher for the high-grade group (1.55±0.52) than that for the low-grade group (0.88±0.43) on SWI (P<0.005).

Conclusion

SWI is useful for grading CRCCs.

Preoperatively evaluating the correlation between pathological grades and blood oxygenation level-dependent MRI in clear cell renal cell carcinomas

RATIONALE AND OBJECTIVES

To assess whether r(2)* values can be used to determine the nuclear grade of clear cell renal cell carcinomas (CRCC).

MATERIALS AND METHODS

A total of 26 patients with pathologically proven CRCCs underwent blood oxygen level-dependent magnetic resonance imaging. r(2)* values were determined for the solid components of CRCC lesions. Histological nuclear grade was determined for each lesion. All patients were divided into low- and high-grade groups. r(2)* values were compared between different grades and between low- and high- grade groups. Receiver operating characteristic curve was drawn to establish the cutoff point for r(2)* values. The correlation between r(2)* values and pathological groups was assessed.

RESULTS

Low-grade group (grades I + II) contained 17 cases and high-grade group (grades III + IV) contained nine cases. The intraclass correlation coefficient for r(2)* values was 0.89. Significant difference was seen between different grades (P < .005). r(2)* values of the high-grade group were higher than the low-grade group (P < .005). A sensitivity of 78% and a specificity of 100% were achieved with a cutoff of 31.87 seconds(-1). r(2)* values directly correlated with pathological groups (P < .005).

CONCLUSION

r(2)* values of CRCCs could be employed as a noninvasive biomarker to help classify the nuclear grade of CRCC.