Small Renal Masses Research Articles

113 Final Results from a Prospective Randomized Pilot Trial of Stereotactic Body Radiation Therapy Versus Radiofrequency Ablation for the Management of Small Renal Masses (RADSTER)

113 Final Results from a Prospective Randomized Pilot Trial of Stereotactic Body Radiation Therapy Versus Radiofrequency Ablation for the Management of Small Renal Masses (RADSTER)

Oral 21 - Long term oncologic and procedural outcomes following percutaneous microwave ablation of small renal masses

Oral 21 - Long term oncologic and procedural outcomes following percutaneous microwave ablation of small renal masses

Percutaneous tumor ablation versus image guided robotic-assisted partial nephrectomy for cT1b renal cell carcinoma: a comparative matched-pair analysis (UroCCR 80).

Partial nephrectomy (PN) is the gold standard treatment for cT1b renal tumors. Percutaneous guided thermal ablation (TA) has proven oncologic efficacy with low morbidity for the treatment of small renal masses (<3 cm). Recently, 3D image-guided robot-assisted PN (3D-IGRAPN) has been described, and decreased perioperative morbidity compared to standard RAPN has been reported. Our objective was to compare two minimally invasive image-guided nephron-sparing procedures (TA vs. 3D-IGRAPN) for the treatment of cT1b renal cell carcinomas (4.1-7 cm). Patients treated with TA and 3D-IGRAPN for cT1b renal cell carcinoma, prospectively included in the UroCCR database (NCT03293563), were pair-matched for tumor size, pathology, and RENAL score. The primary endpoint was the local recurrence rate between the two groups. Secondary endpoints included metastatic evolution, perioperative complications, decrease in renal function, and length of hospitalization. A total of 198 patients were included and matched into two groups of 72 patients. The local recurrence rate was significantly higher in the TA group than that in the 3D-IGRAPN group (4.2% vs. 15.2%, P=0.04). Metastatic evolution and perioperative outcomes such as major complications, eGFR decrease, and length of hospitalization did not differ significantly between the two groups. 3D-IGRAPN resulted in a significantly lower local recurrence rate and comparable rates of complications and metastatic evolution compared with thermal ablation.

PE060 - Minimal surgical impact robotic-assisted partial nephrectomy for the treatment of small renal masses: The role of 3D models in the preoperative planning

PE060 - Minimal surgical impact robotic-assisted partial nephrectomy for the treatment of small renal masses: The role of 3D models in the preoperative planning

VE59 - Robotic-assisted partial nephrectomy with minimal surgical impact after 3D virtual planning for the treatment of small renal masses

VE59 - Robotic-assisted partial nephrectomy with minimal surgical impact after 3D virtual planning for the treatment of small renal masses

The Use of Radiomic Tools in Renal Mass Characterization.

The incidence of renal mass detection has increased during recent decades, with an increased diagnosis of small renal masses, and a final benign diagnosis in some cases. To avoid unnecessary surgeries, there is an increasing interest in using radiomics tools to predict histological results, using radiological features. We performed a narrative review to evaluate the use of radiomics in renal mass characterization. Conventional images, such as computed tomography (CT) and magnetic resonance (MR), are the most common diagnostic tools in renal mass characterization. Distinguishing between benign and malignant tumors in small renal masses can be challenging using conventional methods. To improve subjective evaluation, the interest in using radiomics to obtain quantitative parameters from medical images has increased. Several studies have assessed this novel tool for renal mass characterization, comparing its ability to distinguish benign to malign tumors, the results in differentiating renal cell carcinoma subtypes, or the correlation with prognostic features, with other methods. In several studies, radiomic tools have shown a good accuracy in characterizing renal mass lesions. However, due to the heterogeneity in the radiomic model building, prospective and external validated studies are needed.

Comparison of microwave ablation and partial nephrectomy for T1a small renal masses

ObjectiveTo compare the oncological and renal function outcomes of microwave ablation (MWA) compared to partial nephrectomy (PN) in two small renal mass (SRM) tumor size cohorts, <3 cm and 3–4 cm. Materials and methodsThis study included retrospective data from 2009 to 2015 and prospective data since 2015 from a single-institution database. Patient demographics, renal mass characteristics, and treatment outcomes were collected. Survival curves and hazard analysis were used to assess oncological outcomes. Changes in eGFR and CKD stage following surgery were used to assess renal function outcomes. ResultsA total of 80 PN and 126 MWA patients were analyzed. Median age and Charlson Comorbidity Index (CCI) of MWA patients were greater than PN for each tumor size cohort. Cumulative progression free survival at 36-months was 91% for MWA and 90% for PN. Preoperative renal function was significantly lower in patients undergoing MWA for both tumor sizes, however there was no significant difference in the postoperative change in renal function between MWA and PN for tumors up to 4 cm. ConclusionsOncological outcomes and renal preservation were comparable between MWA and PN cohorts for SRMs <3cm and 3–4cm despite the MWA cohort being older and having more comorbidities. Our findings suggest that MWA can be used as a safe and effective alternative to PN for T1a renal tumors up to 4 cm.

A Review of the Recommendations and Strength of Evidence for Clinical Practice Guidelines on the Management of Small Renal Masses.

Introduction With the rise in the detection of incidental small renal masses (SRM), the management paradigm for these patients has become an issue of increasing concern. We aim to identify areas of consensus, controversy, and opportunities for improvement among recently published guidelines and assess the strength of evidence for the management of SRMs. Methods We reviewed practice guidelines for SRMs promulgated by the American Urological Association, European Association of Urology, National Comprehensive Cancer Network, American Society of Clinical Oncology, European Society for Medical Oncology, and the Chinese Society of Clinical Oncology. Levels of evidence and strength of recommendations for evaluation, management and follow-up were analyzed with regard to consensus, conflict, and neglect. Results There is consensus among guidelines for the initial evaluation and treatment of SRMs, however, discrepancies exist with regard to indications for active surveillance, thermal ablation and timing/method of follow-up after treatment. Routine renal mass biopsy is not recommended by any guideline. Overwhelmingly, guideline statements are based on low to moderate levels of evidence; only 23% of the reviewed guidelines were based on high-level evidence; 38% based on moderate and 39% on low-level evidence or expert opinion. Conclusions Despite all six guidelines sharing a consensus on most management topics regarding SRMs, the ongoing lack of high-level evidence precludes gold standard recommendations in the areas of diagnosis, treatment, and follow-up. More high-quality studies are needed in order to develop stronger, data-supported universal guideline for the management of SRMs.

Robot-assisted partial nephrectomy for complex renal tumors: Analysis of a large multi-institutional database.

Highly complex renal masses pose a challenge to urologic surgeons' ability to perform robotic partial nephrectomy (RPN). Given the increased utilization of the robotic approach for small renal masses, we sought to characterize the outcomes and determine the safety and feasibility of RPN for complex renal masses from our large multi-institutional cohort. We performed a retrospective analysis of patients with R.E.N.A.L. Nephrometry Scores ≥10 who underwent RPN in our multi-institutional cohort (N = 372). Baseline demographic, clinical and tumor related characteristics were evaluated with the primary endpoint of trifecta achievement (defined as negative surgical margin, no major complications, and warm ischemia time ≤25 min). Relationships between variables were assessed using the chi-square test of independence, Fisher exact test, Mann-Whitney U test, and Kruskal Wallis test. Logistic regression was used to evaluate the relationship between baseline characteristics and trifecta achievement. Of 372 patients in the study, mean age was 58 years, and median BMI was 30.49 kg/m2. The median tumor size was 4.3 cm (3.0-5.9 cm). Most of the patients had R.E.N.A.L. scores of 10 (n = 253; 67.01%). Overall, trifecta was achieved in 72.04% of patients. Stratifying intraoperative and postoperative outcomes by R.E.N.A.L. scores, there was no significant difference in trifecta achievement, operative time, warm ischemia time (WIT), open conversion, major complication, or positive margin rates. Length of hospital stay was significantly longer for higher R.E.N.A.L. scores (median days 2 vs. 1, P = 0.012). Multivariate analyses for factors associated with trifecta achievement concluded that age and baseline eGFR were independently associated with trifecta achievement. RPN is a safe and reproducible procedure for complex tumors with R.E.N.A.L. Nephrometry scores ≥10. Our results suggest excellent rates of trifecta achievement and short-term functional outcomes when performed by experienced surgeons. Long-term oncological and functional evaluation are needed to further support this conclusion.

External Validation of a Five-Tiered CT Algorithm for the Diagnosis of Clear Cell Renal Cell Carcinoma: A Retrospective Five-Reader Study.

BACKGROUND. In 2022, a five-tiered CT algorithm was proposed for predicting whether a small (cT1a) solid renal mass represents clear cell renal cell carcinoma (ccRCC). OBJECTIVE. The purpose of this external validation study was to evaluate the proposed CT algorithm for diagnosis of ccRCC among small solid renal masses. METHODS. This retrospective study included 93 patients (median age, 62 years; 42 women, 51 men) with 97 small solid renal masses that were seen on corticomedullary phase contrast-enhanced CT performed between January 2012 and July 2022 and subsequently underwent surgical resection. Five readers (three attending radiologists, two clinical fellows) independently evaluated masses for the mass-to-cortex corticomedullary attenuation ratio and heterogeneity score; these scores were used to derive the CT score by use of the previously proposed CT algorithm. The CT score's sensitivity, specificity, and PPV for ccRCC were calculated at threshold of 4 or greater, and the NPV for ccRCC was calculated at a threshold of 3 or greater (consistent with thresholds in studies of the MRI-based clear cell likelihood score and the CT algorithm's initial study). The CT score's sensitivity and specificity for papillary RCC were calculated at a threshold of 2 or less. Interreader agreement was assessed using the Gwet agreement coefficient (AC1). RESULTS. Overall, 61 of 97 masses (63%) were malignant and 43 of 97 (44%) were ccRCC. Across readers, CT score had sensitivity ranging from 47% to 95% (pooled sensitivity, 74% [95% CI, 68-80%]), specificity ranging from 19% to 83% (pooled specificity, 59% [95% CI, 52-67%]), PPV ranging from 48% to 76% (pooled PPV, 59% [95% CI, 49-71%]), and NPV ranging from 83% to 100% (pooled NPV, 90% [95% CI, 84-95%]), for ccRCC. A CT score of 2 or less had sensitivity ranging from 44% to 100% and specificity ranging from 77% to 98% for papillary RCC (representing nine of 97 masses). Interreader agreement was substantial for attenuation score (AC1 = 0.70), poor for heterogeneity score (AC1 = 0.17), fair for five-tiered CT score (AC1 = 0.32), and fair for dichotomous CT score at a threshold of 4 or greater (AC1 = 0.24 [95% CI, 0.14-0.33]). CONCLUSION. The five-tiered CT algorithm for evaluation of small solid renal masses was tested in an external sample and showed high NPV for ccRCC. CLINICAL IMPACT. The CT algorithm may be used for risk stratification and patient selection for active surveillance by identifying patients unlikely to have ccRCC.

"Is Neutrophil / Lymphocyte Ratio Really Significant in Small Renal Masses?"

"Is Neutrophil / Lymphocyte Ratio Really Significant in Small Renal Masses?"

Factors influencing the decision-making in laparoscopic partial nephrectomy for small renal masses.

We analyzed the factors affecting the decision on surgical approach such as hilum dissection, vessel clamping, and the warm ischemia time (WIT) in laparoscopic partial nephrectomy (LPN) for small renal masses (SRMs). Patients who underwent LPN for SRMs between 2011 and 2021 in two centers were retrospectively screened. Standardized R.E.N.A.L. nephrometry score (RNS) and each of the components were scored on a Likert scale and the effect on the surgical approach was examined by using them separately. A total of 133 patients, 85 of whom were on-clamp and 48 were off-clamp, were included in the study. Greater tumor size, low BMI, higher RNS, upper pole tumor, low exophytic rate, and nearness to the collecting system were statistically significant for both on/off-clamp and hilar dissection decisions. In multivariate analysis, greater tumor size, upper pole tumor, lower rate of exophytic part (E2), nearness to the collecting system (N3) were independent risk factors for vessel clamping. Greater tumor size and lower exophytic tumor rate (E2) were independent risk factors for hilum dissection. We could not identify any factor affecting WIT. Individual components of RNS may serve as a better tool for decision-making on vessel clamping and hilum dissection during LPN for SRMs.

The Judicious Use of Stereotactic Ablative Radiotherapy in the Primary Management of Localized Renal Cell Carcinoma.

Localized renal cell carcinoma is primarily managed surgically, but this disease commonly presents in highly comorbid patients who are poor operative candidates. Less invasive techniques, such as cryoablation and radiofrequency ablation, are effective, but require percutaneous or laparoscopic access, while generally being limited to cT1a tumors without proximity to the renal pelvis or ureter. Active surveillance is another management option for small renal masses, but many patients desire treatment or are poor candidates for active surveillance. For poor surgical candidates, a growing body of evidence supports stereotactic ablative radiotherapy (SABR) as a safe and effective non-invasive treatment modality. For example, a recent multi-institution individual patient data meta-analysis of 190 patients managed with SABR estimated a 5.5% five-year cumulative incidence of local failure with one patient experiencing grade 4 toxicity, and no other grade ≥3 toxic events. Here, we discuss the recent developments in SABR for the management of localized renal cell carcinoma, highlighting key concepts of appropriate patient selection, treatment design, treatment delivery, and response assessment.

Techniques and outcomes of percutaneous tumour ablation for small renal masses.

Small renal masses suspected to be malignant have little potential for metastasis and disease-related mortality. Surgery remains the standard care but represents overtreatment in many cases. Percutaneous ablative technique, especially thermal ablation has emerged as a valid alternative. The increased availability of cross-sectional imaging has led to a large number of incidentally detected small renal masses (SRMs), many of which are of low grade and exhibit indolent behaviour. Since 1996, ablative techniques such as cryoablation, radiofrequency ablation, and microwave ablation have gained widespread acceptance for treatment of SRMs in patients who are not surgical candidates. In this review article, we provide an overview of each of the commonly used percutaneous ablative treatments for SRMs and summarize the current literature regarding the advantages and disadvantages of each technique. Although partial nephrectomy (PN) represents the standard treatment of SRMs, Thermal ablation techniques have been increasingly used showing acceptable efficacy, low complication rate, and equivalent survival. Cryoablation seems to be superior to radiofrequency ablation in terms of local tumour control and retreatment rates. However, selection criteria for thermal ablation are still under refinement.

Does Urologist-level Utilization of Active Surveillance for Low-risk Prostate Cancer Correspond with Utilization of Active Surveillance for Small Renal Masses?

Active surveillance (AS) for prostate cancer (CaP) or small renal masses (SRMs) helps in limiting the overtreatment of indolent malignancies. Implementation of AS for these conditions varies substantially across individual urologists. We examined the Michigan Urological Surgery Improvement Collaborative (MUSIC) registry to assess for correlation of AS between patients with low-risk CaP and patients with SRM managed by individual urologists. We identified 27 urologists who treated at least ten patients with National Comprehensive Cancer Network low-risk CaP and ten patients with SRMs between 2017 and 2021. For surgeons in the lowest quartile of AS use for low-risk CaP (<74%), 21% of their patients with SRMs were managed with AS, in comparison to 74% of patients of surgeons in the highest quartile (>90%). There was a modest positive correlation between the surgeon-level risk-adjusted proportions of patients managed with AS for low-risk CaP and for SRMs (Pearson correlation coefficient 0.48). A surgeon’s tendency to use AS to manage one low-risk malignancy corresponds to their use of AS for a second low-risk condition. By identifying and correcting structural issues associated with underutilization of AS, interventions aimed at increasing AS use may have effects that influence clinical tendencies across a variety of urologic conditions. Patient summaryThe use of active surveillance (AS) for patients with low-risk prostate cancer or small kidney masses varies greatly among individual urologists. Urologists who use AS for low-risk prostate cancer were more likely to use AS for patients with small kidney masses, but there is room to improve the use of AS for both of these conditions.

Renal Mass Imaging with MRI Clear Cell Likelihood Score: A User's Guide.

Small solid renal masses (SRMs) are frequently detected at imaging. Nearly 20% are benign, making careful evaluation with MRI an important consideration before deciding on management. Clear cell renal cell carcinoma (ccRCC) is the most common renal cell carcinoma subtype with potentially aggressive behavior. Thus, confident identification of ccRCC imaging features is a critical task for the radiologist. Imaging features distinguishing ccRCC from other benign and malignant renal masses are based on major features (T2 signal intensity, corticomedullary phase enhancement, and the presence of microscopic fat) and ancillary features (segmental enhancement inversion, arterial-to-delayed enhancement ratio, and diffusion restriction). The clear cell likelihood score (ccLS) system was recently devised to provide a standardized framework for categorizing SRMs, offering a Likert score of the likelihood of ccRCC ranging from 1 (very unlikely) to 5 (very likely). Alternative diagnoses based on imaging appearance are also suggested by the algorithm. Furthermore, the ccLS system aims to stratify which patients may or may not benefit from biopsy. The authors use case examples to guide the reader through the evaluation of major and ancillary MRI features of the ccLS algorithm for assigning a likelihood score to an SRM. The authors also discuss patient selection, imaging parameters, pitfalls, and areas for future development. The goal is for radiologists to be better equipped to guide management and improve shared decision making between the patient and treating physician. © RSNA, 2023 Quiz questions for this article are available in the supplemental material. See the invited commentary by Pedrosa in this issue.

The Journal of Urology® Home Study Course 2023 Volume 209/210.

The Journal of Urology® Home Study Course 2023 Volume 209/210.

Dual Kidney Transplantation: Single-Center Experience

Dual anden blockidney transplantation are strategies used to mitigate the disparity between a reduced organ pool and an ever-increasing need for organ procurement.En blocrefers to the implantation of 2 kidneys from a pediatric donor, compensating for small renal mass, whereas dual expanded criteria donor (DECD) transplantation refers to older donors with grafts otherwise rejected for single transplant, including expanded. This study describes one center's experience with dual anden bloctransplantation. A retrospective cohort study of dual kidney transplants (en bloc and DECD) from 1990 through 2021. The analysis included demographic, clinical, and survival analysis. Of 46 patients who underwent dual kidney transplantation, 17 (37 %) received en-bloc transplantation. The overall mean recipient age was 49.4 ± 13.9 years old, younger in theen-blocsubgroup (39.2 vs 59.8 years old, P < .01). The mean time on dialysis was 37 ± 25 months. Delayed graft function was present in 17.4 % and primary nonfunction in 6.4 %, all from the DECD group. The estimated glomerular filtration rates at 1 and 5 years were 76.7 ± 28.7 and 80.4 ± 24.8 mL/min/1.73 m2, lower in the DECD group (65.9 vs 88.7 mL/min/1.73 m2, P=0.02). Eleven recipients lost their graft during the study period: 63.6% from death with a functioning graft, 27.3% due to chronic graft dysfunction (a mean of 76.3 months after transplantation), and 9.1% due to vascular complications. Subgroup comparison found no differences regarding cold ischemia time or length of hospitalization. Kaplan-Meier estimates, censored for death with a functioning graft, resulted in a mean graft survival of 21.3 ± 1.3 years, with survival rates of 93.5, 90.5, and 84.1% at 1, 5, and 10 years, respectively, without significant differences between subgroups. Both DECD and en bloc strategies provide safe and effective options to further expand the use of otherwise rejected kidneys. Neither of the 2 techniques was superior to the other.

Stimulated Raman histology as a method to determine the adequacy of renal mass biopsy and identify malignant subtypes of renal cell carcinoma.

Renal tumor biopsy requires adequate tissue sampling to aid in the investigation of small renal masses. In some centers the contemporary nondiagnostic renal mass biopsy rate may be as high as 22% and may be as high as 42% in challenging cases. Stimulated Raman Histology (SRH) is a novel microscopic technique which has created the possibility for rapid, label-free, high-resolution images of unprocessed tissue which may beviewed onstandard radiology viewing platforms. The application of SRH to renal biopsy may provide the benefits of routine pathologic evaluation during the procedure, thereby reducing nondiagnostic results. We conducted a pilot feasibility study, to assess if renal cell carcinoma (RCC) subtypes may be imaged and to see if high-quality hematoxylin and eosin (H&E) could subsequently be generated. An 18-gauge core needle biopsy was taken from a series of 25 ex vivo radical or partial nephrectomy specimens. Histologic images of the fresh, unstained biopsy samples were obtained using a SRH microscope using 2 Raman shifts: 2,845 cm-1and 2,930 cm-1. The cores were then processed as per routine pathologic protocols. The SRH images and hematoxylin and eosin (H&E) slides were then viewed by a genitourinary pathologist. The SRH microscope took 8 to 11 minutes to produce high-quality images of the renal biopsies. Total of 25 renal tumors including 1 oncocytoma, 3 chromophobe RCC, 16 clear cells RCC, 4 papillary RCC, and 1 medullary RCC were included. All renal tumor subtypes were captured, and the SRH images were easily differentiated from adjacent normal renal parenchyma. High quality H&E slides were produced from each of the renal biopsies after SRH was completed. Immunostains were performed on selected cases and the staining was not affected by the SRH image process. SRH produces high quality images of all renal cell subtypes that can be rapidly produced and easily interpreted to determine renal mass biopsy adequacy, and on occasion, may allow renal tumor subtype identification. Renal biopsies remained available to produce high quality H&E slides and immunostains for confirmation of diagnosis. Procedural application has promise to decrease the known rate of renal mass nondiagnostic biopsies, and application of convolutional neural network methodology may further improve diagnostic capability and increase utilization of renal mass biopsy among urologists.

Ultrasound Elastography for the Differentiation of Benign and Malignant Solid Renal Masses: A Systematic Review and Meta-Analysis

The incidental finding of small renal masses in CT and MRI examinations can present a diagnostic challenge. Renal cell carcinoma (RCC) and angiomyolipoma (AML) are the most common incidental malignant and benign renal lesions but may present with similar US features. US elastography is a non-invasive technique that can assess tissue elasticity, has shown promising results in many clinical settings, and could be able to differentiate between benign and malignant renal lesions based on tissue stiffness. The purpose of this article is to systematically review the applications of US elastography in the characterization of solid renal masses and to derive and compare the summary estimates of different stiffness values across different lesion subtypes. In December 2022, a systematic search was carried out on the MEDLINE (PubMed) and EMBASE databases to retrieve studies on the application of US elastography in the characterization of solid renal masses. After article selection by three researchers, 14 studies entered qualitative synthesis. A total of 1190 patients were included, and the elastography data of 959 lesions were examined: 317/959 (33%) benign and 642/959 (67%) malignant. Among the malignancies, 590 (91%) were RCC, whereas, among the 317 benign lesions, 244 (77%) were AML. All lesions were classified using a histopathological (biopsy or operative specimen) or imaging (US follow-up/CT/MRI) reference standard. After data extraction and methodological quality evaluation, quantitative synthesis was performed on 12 studies, 4 using strain elastography (SE) and 8 using shear wave elastography (SWE), with single- and double-arm random-effects meta-analyses. Lesion stiffness measured with SE was available in four studies, with an RCC strain ratio higher than the AML strain ratio both in an indirect comparison (Cochran’s Q test p = 0.014) and in a direct comparison (p = 0.021). Conversely, the SWE measurements of RCC and AML stiffness did not significantly differ either at an indirect comparison (p = 0.055) or direct comparison (p = 0.114).