Comprehensive assessment of renal tumour complexity in a large percutaneous cryoablation cohort

Ablation of Kidney Tumors in Patients with Substantial Kidney Impairment: Current Status

PURPOSE OF REVIEW

To review the current status of kidney tumor ablation in patients with substantial kidney impairment.

RECENT FINDINGS

Few reports of kidney tumor ablation in such patients have recently been published. The reported prevalence of patients with stage 4 or 5 chronic kidney disease (CKD) among patients undergoing ablation is 2.0%-10%. In patients with stage 4 or 5 CKD, local tumor control rates were 88%-100%. The effect of ablation on CKD stage is unclear, and the observed deteriorations in kidney function are consistent with both the effect of cryoablation and the natural course of advanced CKD. According to guidelines, active surveillance may be selected. The goals of treatment are complete tumor removal and maintenance of kidney function, both of which can be met by ablation. Given the limited treatment options, ablation may play a pivotal role in the management of patients with advanced CKD.

Predicting Peri-Operative Outcomes in Patients Treated with Percutaneous Thermal Ablation for Small Renal Masses: The SuNS Nephrometry Score

Our objective was to develop a new, simple, and ablation-specific nephrometry score to predict peri-operative outcomes and to compare its predictive accuracy to PADUA and RENAL scores. Overall, 418 patients were treated with percutaneous thermal ablation (microwave and radiofrequency) between 2008 and 2021. The outcome of interest was trifecta status (achieved vs. not achieved): incomplete ablation or Clavien-Dindo ≥ 3 complications or postoperative estimated glomerular filtration rate decrease ≥ 30%. First, we validated the discrimination ability of the PADUA and RENAL scoring systems. Second, we created and internally validated a novel scoring (SuNS) system, according to multivariable logistic regression models. The predictive accuracy of the model was tested in terms of discrimination and calibration. Overall, 89 (21%) patients did not achieve trifecta. PADUA and RENAL scores showed poor ability to predict trifecta status (c-indexes 0.60 [0.53-0.67] and 0.62 [0.55-0.69], respectively). We, therefore, developed the SuNS model (c-index: 0.74 [0.67-0.79]) based on: (1) contact surface area; (2) nearness to renal sinus or urinary collecting system; (3) tumour diameter. Three complexity classes were created: low (3-4 points; 11% of no trifecta) vs. moderate (5-6 points; 30% of no trifecta) vs. high (7-8 points; 65% of no trifecta) complexity. Limitations include the retrospective and single-institution nature of the study. In conclusion, we developed an immediate, simple, and reproducible ablation-specific nephrometry score (SuNS) that outperformed PADUA and RENAL nephrometry scores in predicting peri-operative outcomes. External validation is required before daily practice implementation.

Selective Arterial Embolization with N-Butyl Cyanoacrylate Prior to CT-Guided Percutaneous Cryoablation of Kidney Malignancies: A Single-Center Experience

The study’s purpose was to assess the safety, feasibility and efficiency of selective arterial embolization (SAE) using N-butyl cyanoacrylate (NBCA) glue before percutaneous cryoablation (PCA) of renal malignancies in patients whose tumor characteristics and/or comorbidities resulted in an unacceptable risk of bleeding. In this single-center retrospective study of 19 consecutive high-risk patients (median age, 74 years) with renal malignancies managed in 2017–2020 by SAE with NBCA followed by PCA, data about patients, tumor and procedures characteristics, complications, renal function and hemoglobin concentration before and after treatment, as well as recurrence were collected. Charlson comorbidity index was ≥4 in 89.5% of patients. Ten patients were treated by antiplatelet and/or anticoagulant therapy. Median tumor largest diameter was 3.75 cm (range, 1–6.5 cm) and R.E.N.A.L. nephrometry score was ≥7 in 80%, indicating substantial tumor complexity. No major complications were recorded and minor complications occurred in 7 patients. No residual tumor was found at 6-week imaging follow-up in 18/19 patients. Tumor recurrence was visible in 1/16 patients at 6-month imaging follow-up. No significant difference was found for renal function after treatment (p = 0.07), whereas significant decrease in hemoglobin concentration was noted (p = 0.00004), although it was relevant for only one patient who required only blood transfusion and no further intervention. SAE prior to PCA is safe and effective for managing renal malignancies in high-risk patients.

Percutaneous cryoablation for high-complexity renal masses: complications, functional and oncological outcomes

BACKGROUND

During the past two decades cryoablation (CA) has become a therapeutic option for the management of localized cT1 renal masses in comorbid patients. We analyzed the mid-term functional and oncological outcomes of CA in the treatment of cT1 renal masses which were classified as high-complexity masses according to the PADUA system.

METHODS

A total of 299 patients underwent percutaneous CA between November 2007 and December 2018 in 4 institutions for cT1N0M0 renal masses. All patients with high-complexity (PADUA≥10) renal tumors were included. Technical failure of CA was considered an exclusion criterion.

RESULTS

Inclusion criteria were met by 45 patients. Median Charlson Comorbidity Index (CCI) was 6.0 (IQR: 5.0-7.0), median age was 74 years (IQR: 64.5-79.5). Seven Clavien 1 and 1 Clavien 2 procedure-related complications were reported. Median eGFR at baseline was 64.3mL/min (IQR: 52.0-82.3) while at the 1-year follow-up was 61.4 mL/min (IQR: 44.0-74.5). The median follow-up was 32 months (IQR: 13.25-47.5). Local recurrences were detected in 6 patients; 3 of them underwent re-cryoablation while the others started active surveillance. Median time to recurrence was 17.5 months (IQR: 7.8-27.3). Cancer-specific survival and metastasis-free survival were 100%, while overall survival was 86.7%.

CONCLUSIONS

CA proved to be a valuable therapeutic option for the management of patients with cT1 high-complexity PADUA≥10 renal tumors as it provides a low rate of procedural morbidity and good preservation of renal function. However, these results are counterbalanced by a recurrence rate that appears to be higher than those reported on surgically treated patients.

Ten-Year Experience with Percutaneous Cryoablation of Renal Tumors: Tumor Size Predicts Disease Progression

Introduction: Percutaneous cryoablation (PCA) has emerged as an alternative to extirpative management of small renal masses (SRMs) in select patients, with a reduced risk of perioperative complications. Although disease recurrence is thought to occur in the early postoperative period, limited data on long-term oncologic outcomes have been published. We reviewed our 10-year experience with PCA for SRMs and assessed predictors of disease progression. Materials and Methods: We reviewed our prospectively maintained database of patients who underwent renal PCA from March 2005 to December 2015 (n = 308). Baseline patient and tumor variables were recorded, and postoperative cross-sectional imaging was examined for evidence of disease recurrence. Disease progression was defined as the presence of local recurrence or new lymphadenopathy/metastasis. Results: Mean patient age was 67.2 ± 11 years, mean tumor size was 2.7 ± 1.3 cm, and mean nephrometry score was 6.8 ± 1.7. At mean follow-up of 38 months, local recurrence and new lymphadenopathy/metastasis occurred in 10.1% (31/308) and 6.2% (19/308) of patients, respectively. Excluding patients with a solitary kidney and/or von Hippel-Lindau, local recurrence and new lymphadenopathy/metastasis occurred in 8.6% (23/268) and 1.9% (5/268) of cases, respectively. Kaplan-Meier estimated disease-free survival was 92.5% at 1 year, 89.3% at 2 years, and 86.7% at 3 years post-PCA. Increasing tumor size was a significant predictor of disease progression (hazard ratio 1.32 per 1-cm increase in size, p = 0.001). Conclusions: PCA is a viable treatment option for patients with SRMs. Increasing tumor size is a significant predictor of disease progression following PCA.

Association among the R.E.N.A.L. nephrometry score and clinical outcomes in patients with small renal masses treated with percutaneous contrast enhanced ultrasound radiofrequency ablation

Introduction

An association between the R.E.N.A.L. nephrometry score (RNS) and clinical outcomes in patients with a small renal mass (SRM) has been proposed. We analyzed clinical outcomes according to the RNS in patients with a SRM treated with percutaneous contrast enhanced ultrasound (CEUS) radiofrequency ablation (RFA).

Material and methods

Patients with a SRM, who underwent RFA between January 2005 and March 2015, were retrospectively identified. The association between RNS and clinical outcomes was evaluated using parametric and non-parametric analysis.

Results

We analyzed 163 SRMs in 149 consecutive patients. The mean age was 71.7 years. Mean follow-up time was 33.3 months ±20.6 (2-102). The mean RNS was 5.6 ±1.52 (4-11). A total of 121 (74.2%) cases were of low complexity and 42 (25.8%) were medium complexity. We identified 11 cases of tumor persistence (6.7%). The mean RNS was 5.58 in the cases with no persistence and 5.73 in the cases with persistence (p = 0.788). We identified 15 (9.2%) cases of recurrence. The mean RNS was 5.57 ±0.1 (4-11) in the cases without recurrence and 5.73 ±0.4 (4-9) in recurrence cases (p = 0.804). Of the 76 biopsy proven RCC cases, 8 (10.5%) cases of recurrence were observed, 5 in the low complexity group and 3 in the medium complexity group (p = 0.690). A total of 9 (5.5%) cases of complications were observed, with 5 (4.3%) in the low complexity group and 4 cases in the medium complexity group (p = 0.23). The mean length of stay was 1.5 days with a significant difference between low and medium complexity groups (1.3 vs. 2.1 days, p = 0.02). The mean difference between preoperative eGFR and estimated eGFRat 12 months was -3.08 mL / min ±13.3 (-49.4-34.1) and was significant (p = 0.008).However, this variation did not show significant differences between the low and medium complexity groups (p = 0.936). All-cause mortality was 11.7%, 14 cases (11.6%) in the low complexity group and 5 (11.9%) in the medium complexity group (p = 1.0). No cases of renal cell carcinoma (RCC) specific mortality were identified.

Conclusions

The RNS was not associated with tumor persistence, recurrence, cancer specific mortality, complications or renal function 12 months after the first treatment, showing significant difference only in length of hospital stay between low and medium complexity groups.

[Ablative therapy of small renal masses]

Renal cell cancer is nowadays predominantly diagnosed in early stages due to the widespread use of sectional imaging for unrelated symptoms. Small renal masses (<4 cm) feature a largely indolent biology with a very low risk for metastasis or even a benign biology in up to 30% of the cases. Consequently, there is a need for less invasive therapeutic alternatives to nephron-sparing surgery. Meanwhile, there is a broad portfolio of local ablation techniques to treat small renal tumors. These include the extensively studied radiofrequency ablation and cryoablation techniques as well as newer modalities like microwave ablation and irreversible electroporation as more experimental techniques. Tumor ablation can be performed percutaneously under image guidance or laparoscopically. In particular, the percutaneous approach is a less invasive alternative to nephron-sparing surgery with lower risk for complications. Comparative studies and meta-analyses report a higher risk for local recurrence after renal tumor ablation compared to surgery. However, long-term oncological results after treatment of small renal masses are promising and do not seem to differ from partial nephrectomy. The possibility for salvage therapy in case of recurrence also accounts for this finding. Especially old patients with an increased risk of surgical and anesthesiological complications as well as patients with recurrent and multiple hereditary renal cell carcinomas may benefit from tumor ablation. Tumor biopsy prior to intervention is associated with very low morbidity rates and is oncologically safe. It can help to assess the biology of the renal mass and prevent therapy of benign lesions.

Cryoablation versus Partial Nephrectomy for Clinical Stage T1 Renal Masses: A Systematic Review and Meta-Analysis

Introduction: Cryoablation has been considered as the most efficacious ablative alternative to partial nephrectomy (PN) for selected patients. Our objective is to assess the existing evidence relating to the safety and efficacy of cryoablation compared with PN for clinical T1 renal masses.

Materials and Methods: A comprehensive search of PMC, EMBASE, and the Cochrane Library was conducted to identify studies containing comparison of cryoablation and PN. By utilizing those included studies, a systematic review and cumulative meta-analyses were performed to assess the safety and efficacy between cryoablation and PN for T1 renal masses.

Results: 17 retrospective studies providing available data were included in our study. Significant differences were found about all oncological variables including all-cause death, cancer-specific death, metastasis and local-recurrence (p < 0.001, p = 0.03, p < 0.001, and p < 0.001, respectively) between the PN group and the cryoablation group. The mean difference between two groups for percent estimated glomerular filtration rate decrease and creatinine increase was -4.84 and 0.15 respectively (p < 0.001 and p = 0.006, respectively). The incidences of overall and postoperative complications in the PN group were significantly higher than that in the cryoablation group (p = 0.001 and p < 0.001, respectively), but the result about intraoperative complications didn't show a significant difference between the two groups (p = 0.53).

Conclusions: Comparing with PN, cryoablation for clinical T1 renal tumors is associated with poorer oncological outcomes, but the existing disadvantages are accompanied by lower rate of overall and postoperative complications and superior renal functional preservation. For patients with imperative indications for nephron-sparing surgery who can't risk more invasive PN, cryoablation could be an attractive option. Owing to the inherent limitations of eligible studies, conclusions drawn from our meta-analyses should be interpreted cautiously and be confirmed further with well-designed randomized controlled trials with extensive follow-up length.

Predicting Renal Function Outcomes After Partial and Radical Nephrectomy

BACKGROUND

Partial nephrectomy (PN) is generally favored for cT1 tumors over radical nephrectomy (RN) when technically feasible. However, it can be unclear whether the additional risks of PN are worth the magnitude of renal function benefit.

OBJECTIVE

To develop preoperative tools to predict long-term estimated glomerular filtration rate (eGFR) beyond 30d following PN and RN, separately.

DESIGN, SETTING, AND PARTICIPANTS

In this retrospective cohort study, patients who underwent RN or PN for a single nonmetastatic renal tumor between 1997 and 2014 at our institution were identified. Exclusion criteria were venous tumor thrombus and preoperative eGFR <15ml/min/1.73m².

INTERVENTION

RN and PN.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Hierarchical generalized linear mixed-effect models with backward selection of candidate preoperative features were used to predict long-term eGFR following RN and PN, separately. Predictive ability was summarized using marginal R_GLMM², which ranges from 0 to 1, with higher values indicating increased predictive ability.

RESULTS AND LIMITATIONS

The analysis included 1152 patients (13 206 eGFR observations) who underwent RN and 1920 patients (18 652 eGFR observations) who underwent PN, with mean preoperative eGFRs of 66ml/min/1.73m² (standard deviation [SD]=18) and 72ml/min/1.73m² (SD=20), respectively. The model to predict eGFR after RN included age, diabetes, preoperative eGFR, preoperative proteinuria, tumor size, time from surgery, and an interaction between time from surgery and age (marginal R_GLMM²=0.41). The model to predict eGFR after PN included age, presence of a solitary kidney, diabetes, hypertension, preoperative eGFR, preoperative proteinuria, surgical approach, time from surgery, and interaction terms between time from surgery and age, diabetes, preoperative eGFR, and preoperative proteinuria (marginal R_GLMM²). Limitations include the lack of data on renal tumor complexity and the single-center design; generalizability needs to be confirmed in external cohorts.

CONCLUSIONS

We developed preoperative tools to predict renal function outcomes following RN and PN. Pending validation, these tools should be helpful for patient counseling and clinical decision-making.

PATIENT SUMMARY

We developed models to predict kidney function outcomes after partial and radical nephrectomy based on preoperative features. This should help clinicians during patient counseling and decision-making in the management of kidney tumors.

Outcomes After Cryoablation Versus Partial Nephrectomy for Sporadic Renal Tumors in a Solitary Kidney: A Propensity Score Analysis

BACKGROUND

While partial nephrectomy (PN) is considered the standard approach for a tumor in a solitary kidney, percutaneous cryoablation (PCA) is emerging as an alternative nephron-sparing option.

OBJECTIVE

To compare outcomes between PCA and PN for tumors in a solitary kidney.

DESIGN, SETTING, AND PARTICIPANTS

Patients who underwent PCA or PN between 2005 and 2015 for a single primary renal tumor in a solitary kidney were identified using Mayo Clinic Registries. Exclusion criteria were inherited tumor syndromes and salvage procedures.

INTERVENTION

PCA and PN.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

To achieve balance in baseline characteristics, we used inverse probability of treatment weighting (IPTW) based on propensity to receive treatment. The risk of having a post-treatment complication and percent drop in estimated glomerular filtration rate (eGFR), as well as the risks of local/ipsilateral recurrence, distant metastasis, and cancer-specific mortality, were compared between groups using logistic, linear, and Fine-and-Gray competing risk regression models.

RESULTS AND LIMITATIONS

The cohort included 118 patients (PCA: 54; PN: 64) with a median follow-up of 47 mo (interquartile range 18, 74). In unadjusted analyses, PCA was associated with a lower risk of complications (15% vs 31%; odds ratio [OR]=0.38; 95% confidence interval [CI] 0.15, 0.96; p=0.04). However, upon accounting for baseline differences with IPTW adjustment, there was no longer a significant difference in the risk of complications (28% vs 29%; OR=0.95; 95% CI 0.53, 1.69; p=0.9). There were no significant differences between PCA and PN in percentage drop in eGFR at discharge (mean: 11% vs 16%; β=-5%; 95% CI -13, 3; p=0.2) or at 3 mo (12% vs 9%; β=3%; 95% CI -3, 10; p=0.3). Likewise, no significant differences were noted in local recurrence (HR=0.87; 95% CI 0.38, 1.98; p=0.7), distant metastases (HR=0.60; 95% CI 0.30, 1.20; p=0.2), or cancer-specific mortality (HR=1.13; 95% CI 0.32, 3.98; p=0.8). Limitations include the sample size, given the relative rarity of renal masses in solitary kidneys.

CONCLUSIONS

Our study found no significant difference in complications, renal function outcomes, and oncologic outcomes between PN and PCA for patients with a tumor in a solitary kidney. Validation in a larger multi-institutional analysis may be warranted.

PATIENT SUMMARY

Partial nephrectomy (surgery) and percutaneous cryoablation are both options for treating a kidney tumor while preserving the normal portion of the kidney. In patients with a tumor in their only kidney, we found no difference in the risk of complications, kidney function outcomes, or cancer control outcomes between these two approaches.

Renal functional outcomes in patients undergoing percutaneous cryoablation or partial nephrectomy for a solitary renal mass

OBJECTIVES

To compare renal functional changes after percutaneous cryoablation (PCA) or partial nephrectomy (PN).

PATIENTS AND METHODS

Patients who underwent PCA or PN for a solitary renal mass at a single institution were identified (2003-2013). Estimated glomerular filtration rates (eGFRs) were calculated at baseline, discharge, and at the 3-month follow-up using the Chronic Kidney Disease Epidemiology Collaboration equation. Changes in renal function were compared between groups using 1:1 propensity score (PS) matching, adjustment for PS quintile, and inverse probability weighting (IPW).

RESULTS

There were 2 040 procedures available for the PS analyses, including 448 PCA and 1 592 PN. After PS adjustments, there were no significant differences in baseline clinical features between PCA and PN patients. In the PS-matched analysis, the change in eGFR from baseline to discharge for PCA and PN patients was -3.1 and -1.1 mL/min/1.73 m² , respectively (P = 0.038), with percentage changes of -4.5% and 0% respectively (P = 0.006). From baseline to the 3-month follow-up, the absolute change in eGFR for PCA and PN patients was -4.3 and -2.1 mL/min/1.73 m² , respectively (P = 0.008), and the percentage change was -6.1% and -2.4% respectively (P = 0.005). Similar results were obtained after adjusting for PS quintiles and in the IPW analysis. Importantly, the rate of chronic kidney disease stage progression at the 3-month follow-up was similar between the groups (21% vs 18%).

CONCLUSIONS

Our results confirm that both PCA and PN have a minor impact on renal function. While we observed a statistically greater decline in eGFR after PCA compared with PN, both approaches result in excellent preservation of renal function.

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.