Renal Cryoablation Versus Robot-Assisted Partial Nephrectomy: Washington University Long-Term Experience

Comparative efficacy of cryoablation versus robot-assisted partial nephrectomy in the treatment of cT1 renal tumors: a systematic review and meta-analysis

PURPOSE

This study utilizes a meta-analytic approach to investigate the effects of cryoablation and robot-assisted partial nephrectomy on perioperative outcomes, postoperative renal function, and oncological results in patients.

METHODS

This study followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. Four electronic databases (PubMed, Embase, Web of Science, and the Cochrane Library database) were systematically searched to identify relevant studies published in English up to November 2023. The primary outcomes were perioperative results, complications, postoperative renal function and oncologic outcomes. Review Manager 5.4 was used for this analysis.

RESULTS

This study included a total of 10 studies comprising 2,011 patients. Compared to RAPN (Robot-Assisted Partial Nephrectomy), the CA (Cryoablation) group had a shorter hospital stay [MD -1.76 days; 95% CI -3.12 to -0.41; p = 0.01], less blood loss [MD -104.60 ml; 95% CI -152.58 to -56.62; p < 0.0001], and fewer overall complications [OR 0.62; 95% CI 0.45 to 0.86; p = 0.004], but a higher recurrence rate [OR 7.83; 95% CI 4.32 to 14.19; p < 0.00001]. There were no significant differences between the two groups in terms of operative time, minor complications (Clavien-Dindo Grade 1-2), major complications (Clavien-Dindo Grade 3-5), changes in renal function at 12 months post-operation, RFS (Recurrence-Free Survival), and OS (Overall Survival).

CONCLUSION

The evidence provided by this meta-analysis indicates that the therapeutic effects of Cryoablation (CA) are similar to those of Robot-Assisted Partial Nephrectomy (RAPN) in terms of perioperative outcomes and renal function. However, the recurrence rate of tumors treated with CA is significantly higher.

SYSTEMATIC REVIEW REGISTRATION

The study has been registered on the International Prospective Register of Systematic Reviews (PROSPERO: CRD42023465846).

Minimally invasive nephron-sparing treatments for T1 renal cell cancer in patients over 75 years: a comparison of outcomes after robot-assisted partial nephrectomy and percutaneous ablation

PURPOSE

To compare the oncological and perioperative outcomes of robot-assisted partial nephrectomy (RPN) and percutaneous thermal ablation (PTA) for treatment of T1 renal cell cancer (RCC) in patients older than 75 years.

MATERIALS AND METHODS

Retrospective national multicenter study included all patients older than 75 years treated for a T1 RCC by RPN or PTA between January 2010 and January 2021. Patients' characteristics, tumor data, and perioperative and oncological outcomes were compared.

RESULTS

A total of 205 patients for 209 procedures (143 RPN and 66 PTA) were included. In the PTA group, patients were older (80.4 ± 3.7 vs. 79 ± 3.7 years (p = 0.01)); frailer (ASA score (2.43 ± 0.6 vs. 2.17 ± 0.6 (p < 0.01)); and more frequently had a history of kidney surgery (16.7% [11/66] vs. 5.6% [8/143] (p = 0.01)) than in the RPN group. Tumors were larger in the RPN group (2.7 ± 0.7 vs. 3.2 ± 0.9 cm (p < 0.01)). Operation time, length of hospital stay, and increase of creatinine serum level were higher in RPN (respectively 92.1 ± 42.7 vs. 150.7 ± 61.3 min (p < 0.01); 1.7 ± 1.4 vs. 4.2 ± 3.4 days (p < 0.01); 1.9 ± 19.3% vs. 10.1 ± 23.7 (p = 0.03)). Disease-free survival and time to progression were similar (respectively, HR 2.2; 95% CI 0.88-5.5; p = 0.09; HR 2.1; 95% CI 0.86-5.2; p = 0.1). Overall survival was shorter for PTA that disappeared after Cox adjusting model (HR 3.3; 95% CI 0.87-12.72; p = 0.08).

CONCLUSION

Similar oncological outcomes are observed after PTA and RPN for T1 RCC in elderly patients.

CLINICAL RELEVANCE STATEMENT

Robot-assisted partial nephrectomy and percutaneous thermal ablation have similar oncological outcomes for T1a kidney cancer in patients over 75 years; however, operative time, decrease in renal function, and length of hospital stay were lower with ablation.

KEY POINTS

• After adjusting model for age and ASA score, similar oncological outcomes are observed after percutaneous thermal ablation and robot-assisted partial nephrectomy for T1 renal cell cancer in elderly patients. • Operation time, length of hospital stay, and increase of creatinine serum level were higher in the robot-assisted partial nephrectomy group.

Percutaneous Renal Tumor Cryoablation Effect on Renal Function

Background: Percutaneous cryoablation (PCA) of renal tumors is a well-established alternative to partial nephrectomy, but the effects on renal function after the procedure are not well-documented. The purpose of this study was to evaluate renal function after computed tomography-guided PCA. Materials and Methods: A retrospective cohort study including 259 patients treated with PCA at Odense University Hospital, Denmark from January 1, 2015 to December 31, 2019. Both patients with malignant (96%) and benign tumors (4%) were included. Mean age of patients was 66.5 years (standard deviation [SD] = 10.9, range: 27-91) and 174 (67%) patients were men. Baseline estimated glomerular filtration rate (eGFR) was recorded at baseline and 12 months after cryoablation. Results: Mean tumor size was 27.5 mm (SD = 10.0) distributed in seven different histopathological types, mainly clear cell renal-cell carcinoma (RCC) (64%) and papillary RCC (22%). Mean eGFR at baseline was 73.7 mL/min/1.73 m2 (SD = 23.2) with a follow-up mean eGFR of 69.7 (SD = 23.7) (p < 0.0001). At baseline before intervention 190 patients (73%) had eGFR matching chronic kidney disease (CKD) groups 1 and 2 (normal to mild CKD), 64 patients (24%) matching CKD group 3 (average CKD), and 1% in groups 4 and 5. At 12-month follow-up, 171 patients (66%) had eGFR matching CKD groups 1 and 2, 77 patients (30%) matching CKD group 3 and 11 patients (4%) matching CKD groups 4 and 5. In patients with skewed renography who had PCA in the kidney with better excretion, eGFR at baseline was 64.7 and 61.2 at follow-up (p = 0.703). Conclusions: This study showed minimal decline in renal function 12 months after PCA, even for patients with reduced renal function. PCA is therefore considered a safe and relevant intervention.

Cost-effectiveness of minimally invasive partial nephrectomy and percutaneous cryoablation for cT1a renal cell carcinoma

BACKGROUND

There is growing evidence that partial nephrectomy (PN) and percutaneous cryoablation (PCA) yield comparable outcomes for patients with cT1a renal cell carcinoma (RCC), although the cost-effectiveness of both treatments still needs to be assessed.

PURPOSE

To perform a cost-effectiveness analysis of PN and PCA for patients with cT1a RCC.

MATERIALS AND METHODS

A decision analysis was created over a 5-year span from a healthcare payer's perspective computing expected costs and outcomes of PN and PCA in terms of quality-adjusted life-years (QALYs) and incremental cost-effectiveness (ICER). After each treatment, the following states were modelled using data from the recent literature: procedural complications, no evidence of disease (NED), local recurrence, metastases, and death from RCC- or non-RCC-related causes. Probabilistic and deterministic sensitivity analyses were performed.

RESULTS

PCA and PN yielded health benefits of 3.68 QALY and 3.67 QALY. Overall expected costs were $20,491 and $26,478 for PCA and PN. On probabilistic sensitivity analysis, PCA was more cost-effective than PN in 84.78% of Monte Carlo simulations. PCA was more cost-effective until its complication risk was at least 38% higher than PN. PCA was more cost-effective than PN when (i) PCAs annual local recurrence risk was < 3.5% higher than that of PN in absolute values; (ii) PCAs annual metastatic risk was < 1.0% higher than that of PN; or (iii) PCAs annual cancer-specific mortality risk < 0.65% higher than that of PN. PCA remained cost-effective until its procedural cost is above $13,875.

CONCLUSION

PCA appears to be more cost-effective than PN for the treatment of cT1a RCC, although the currently available evidence is of limited quality. PCA may be the better treatment strategy in the majority of scenarios varying procedural complications, recurrence, metastatic risk, and RCC-mortality in clinically plausible ranges.

KEY POINTS

• For patients with cT1a RCCs, PCA yields a comparable health benefit at lower costs compared to PN, making PCA the dominant and therefore more cost-effective treatment strategy over PN. • PCA was more cost-effective than PN when (i) PCAs annual local recurrence risk was < 3.5% higher than PN in absolute values; (ii) PCAs annual metastatic risk was < 1.0% higher than PN; or (iii) PCAs annual cancer-specific mortality risk < 0.65% higher than PN. • PCA is more cost-effective than PN for the treatment of cT1a RCC, and it remained so in the majority of scenarios varying procedural complications, recurrence, metastatic risk, and RCC mortality.

Safety, efficacy, and mid-term oncological outcomes of computed tomography-guided cryoablation of T1 renal cancer

BACKGROUND

Cryoablation is a promising minimally invasive, nephron-sparing treatment of small renal carcinoma (RCC) in co-morbid patients.

PURPOSE

To assess the safety, efficacy, and cancer-specific outcomes of computed tomography (CT)-guided cryoablation of stage T1 (RCC).

MATERIAL AND METHODS

A retrospective evaluation of 122 consecutive patients with 128 tumors treated with cryoablation during 2016-2017. All patients had biopsy-verified T1 RCC.

RESULTS

Median age was 69 years (IQR=59-76); 69% were male. Median tumor size was 26 mm (± 20-33); 9% were stage T1b. Mean follow-up time was 36.3±12.0 months. In total, 14 (11%) procedures led to complications, of which 4 (3%) were intraoperative, 5 (4%) appeared ≤30 days and 5 (4%) >30 days after treatment. Major complications arose after 4 (3%) procedures. Statistically significant associations were found between major complications and stage T1b (P = 0.039), RENAL score (P = 0.010), and number of needles used in cryoablation (P = 0.004). Residual tumor was detected after 4 (3%) procedures and 5 (4%) tumors had local tumor progression. Of 122 patients, 3 (2%) advanced to metastatic disease. Significant statistical associations were found between local tumor progression and T1b stage tumors and number of needles used in cryoablation (P = 0.05 and P = 0.004, respectively). For patients with T1a tumors, the one- and three-year disease-free survival was 98% and 95%, respectively, and for T1b 100% after one year and 75% after three years.

CONCLUSIONS

This study showed that cryoablation is a safe and effective treatment of stage T1 RCC and suggests that in selecting candidates for cryoablation of RCC, the tumor characteristics are more critical than patients' baseline health status.

Percutaneous thermal ablation for cT1 renal mass in solitary kidney: A multicenter trifecta comparative analysis versus robot-assisted partial nephrectomy

INTRODUCTION

Renal cell carcinoma (RCC) in solitary kidney (SK) represents a challenging scenario. We sought to compare outcomes of robot-assisted partial nephrectomy (RAPN) versus percutaneous thermal ablation (PTA) in SK patients with renal tumors cT1.

MATERIALS AND METHODS

We performed a multicenter retrospective analysis of SK patients treated for RCC. The PTA group included cryoablation or radiofrequency ablation. We collected baseline characteristics, intraoperative, pathological, and post-operative data. We applied an arbitrary composite "trifecta" to assess surgical, functional, and oncological outcomes, only for malignant histology. RFS analysis was performed using the Kaplan-Meier method. Multivariable regression analysis was performed to determine independent predictors of "trifecta" achievement.

RESULTS

We included 198 SK patients (RAPN, n = 50; PTA n = 119). Mean clinical tumor size was not significantly different while R.E.N.A.L. score was higher for RAPN (p < 0.001). No differences in intra and major post-procedural complications. Recurrence rate was higher in PTA group but not statistically significant (p < 0.328). No difference in metastasis rate was found (p = 0.435). RFS was 96.1% in RAPN and 86.8% in PTA cohort (p = 0.003) while no difference in PFS was detected (p = 0.1). Trifecta was achieved in 72.5% of RAPN vs 77.3% of PTA (p = 0.481). Multivariable analysis has not detected predictors for Trifecta achievement.

CONCLUSION

PTA offers good outcomes in the management of SK patients with RCC. Compared with RAPN, it might carry a higher risk of recurrence; on the other hand, re-treatment is possible. Overall, PTA can be safely offered to treat SK patients presenting RCC. In general, it should be preferred in more frail patients to minimize the risk of complications.

Partial Nephrectomy versus Percutaneous Cryoablation of Small Renal Cell Carcinomas: A Comparison of Adverse Events in a Prospective Multicenter Cohort Study

PURPOSE

To assess and compare complications and readmissions after partial nephrectomy and percutaneous cryoablation of cT1 renal cell carcinoma (RCC).

MATERIALS AND METHODS

Patients treated for cT1 RCC between 2019 and 2021 were prospectively and consecutively enrolled. Complications recorded within 30 and 90 days were graded according to the Clavien-Dindo classification, and percutaneous cryoablation was graded according to the Society of Interventional Radiology classification of adverse events. Major complications were defined as complications with a grade of ≥3 based on the Clavien-Dindo classification. Readmission within 30 days was recorded.

RESULTS

The cohort included 86 partial nephrectomies and 104 cryoablations. The complication rate within 90 days was 23% after partial nephrectomy and cryoablation (P = .98), with major complication rates of 3% after partial nephrectomy and 10% after cryoablation (P = .15). The readmission rates were 14% and 11% after partial nephrectomy and cryoablation, respectively (P = .48). Double-J stents were associated with overall complications (odds ratio [OR], 9.88; 95% confidence interval [CI], 2.18-44.68; P = .003) and readmissions (OR, 5.39; 95% CI, 1.37-21.06; P = .015) after cryoablation. A high versus low radius-endophytic-nearness-anterior-location score (OR, 5.86; 95% CI, 1.08-31.81; P = .040) and endophytic location (OR, 7.70; 95% CI, 1.72-34.50; P = .008) were associated with a higher complication rate after cryoablation. The Charlson Comorbidity Index (CCI) was associated with major complications after partial nephrectomy (OR, 2.12; 95% CI, 1.05-4.30; P = .036).

CONCLUSIONS

Partial nephrectomy and cryoablation are comparable regarding complications within 90 days after treatment. Tumor complexity and double-J stents were associated with complications after cryoablation, and a high CCI was associated with complications after partial nephrectomy.

A Systematic Review and Meta-Analysis of Minimally Invasive Partial Nephrectomy Versus Focal Therapy for Small Renal Masses

Background

Minimally invasive partial nephrectomy (MIPN) and focal therapy (FT) are popular trends for small renal masses (SRMs). However, there is currently no systematic comparison between MIPN and FT of SRMs. Therefore, we systematically study the perioperative, renal functional, and oncologic outcomes of MIPN and FT in SRMs.

Methods

We have searched the Embase, Cochrane Library, and PubMed for articles between MIPN (robot-assisted partial nephrectomy and laparoscopic partial nephrectomy) and FT {radiofrequency ablation (RFA), microwave ablation (MWA), cryoablation (CA), irreversible electroporation, non-thermal [irreversible electroporation (IRE)] ablation, and stereotactic body radiation therapy (SBRT)}. We calculated pooled mean difference (MD), odds ratios (ORs), and 95% confidence intervals (CIs) (CRD42021260787).

Results

A total of 26 articles (n = 4,420) were included in the study. Compared with MIPN, the operating time (OP) of FT had significantly lower (SMD, −1.20; CI, −1.77 to −0.63; I2 = 97.6%, P &lt; 0.0001), estimated blood loss (EBL) of FT had significantly less (SMD, −1.20; CI, −1.77 to −0.63; I2 = 97.6%, P &lt; 0.0001), length of stay (LOS) had shorter (SMD, −0.90; CI, −1.26 to −0.53; I2 = 92.2%, P &lt; 0.0001), and estimated glomerular filtration rate (eGFR) of FT was significantly lower decrease (SMD, −0.90; CI, −1.26 to −0.53; I2 = 92.2%, P &lt; 0.0001). However, FT possessed lower risk in minor complications (Clavien 1–2) (OR, 0.69; CI, 0.45 to 1.07; I2 = 47%, P = 0.023) and overall complications (OR, 0.71; CI, 0.51 to 0.99; I2 = 49.2%, P = 0.008). Finally, there are no obvious difference between FT and MIPN in local recurrence, distant metastasis, and major complications (P &gt; 0.05).

Conclusion

FT has more advantages in protecting kidney function, reducing bleeding, shortening operating time, and shortening the length of stay. There is no difference in local recurrence, distant metastasis, and major complications. For the minimally invasive era, we need to weigh the advantages and disadvantages of all aspects to make comprehensive choices.

Systematic Review Registration

https://www.crd.york.ac.uk/PROSPERO/#recordDetails, identifier PROSPERO (CRD42021260787).

Therapeutic and Clinical Outcomes of Robot-assisted Partial Nephrectomy Versus Cryoablation for T1 Renal Cell Carcinoma

BACKGROUND

In cT1 renal cell carcinoma (RCC), very few studies have compared oncological outcomes and renal function preservation rates in nephron-sparing robot-assisted partial nephrectomy (RAPN) and percutaneous cryoablation (PCA).

PATIENTS AND METHODS

We retrospectively analysed 126 patients with cT1 RCC treated with RAPN (n=78) and computed tomography-guided PCA (n=48) between March 2016 and November 2019. Clinical data and outcomes were compared for the two groups.

RESULTS

There were no significant differences in the 3-year overall survival and relapse-free survival rates in the two groups (p=0.17 and p=0.093, respectively). The median percentage of estimated glomerular filtration rate preservation at 6 months after surgery was 91.8% and 91.4% in the RAPN and PCA groups, respectively (p=0.9).

CONCLUSION

In patients with cT1a RCC, oncological outcomes and renal function appear similar following RAPN and PCA.

Stereotactic Body Radiotherapy for Palliation of Hematuria Arising From Urothelial Carcinoma of the Kidney in Unfavorable Surgical Candidates

INTRODUCTION

Hematuria can be a distressing and debilitating complication of urothelial carcinoma (UC) of the kidney for patients who are not candidates for surgery or ureteroscopic ablation. We retrospectively assessed the efficacy, tolerability, and safety of stereotactic body radiotherapy (SBRT) for controlling gross hematuria in this patient population.

MATERIALS AND METHODS

Institutional Review Board (IRB)-approved review of the records, laboratory values, pathology, and imaging of 8 consecutive patients treated with SBRT over a 5-year period for uncontrolled gross hematuria caused by UC of the renal pelvis or calyces.

RESULTS

Therapy was delivered in 3 to 5 treatments over 1 to weeks. Individual treatments lasted an average of 17.2 minutes. No patient experienced treatment-related pain, vomiting, or diarrhea. All enjoyed cessation of bleeding within a week of completing therapy. Hematuria recurred in 2 patients in 4 and 22 months. Of the patients who have not re-bled, 3 expired of metastatic disease or co-morbidities, and 3 remain alive up to 6 years posttreatment. Of patients who have survived longer than a year, creatinine has changed by -0.05 to +0.35, and estimated glomerular filtration rate has fallen by an average of 22%. No patient has required dialysis.

CONCLUSIONS

SBRT appears to be an effective and well-tolerated means of palliating gross hematuria secondary to UC of the renal pelvis or calyces in patients who are unfavorable candidates for nephrectomy or ureteroscopic ablation. Treatment was associated with a moderate decline in renal function.

Percutaneous thermoablation of small renal masses (T1a) in surgical candidate patients: oncologic outcomes

OBJECTIVE

To evaluate the local tumour progression-free survival (LTPFS), metastasis-free survival (MFS), cancer-specific survival (CSS) and overall survival (OS) of healthy surgical candidates who underwent percutaneous thermoablation (TA) as a first-line therapy for small renal masses (T1a).

METHODS

The institutional review board approved this bi-institutional retrospective study of 85 consecutive surgical candidates with 97 biopsy-proven malignant renal masses (T1a) treated with percutaneous TA from 2008 to 2016. The LTPFS, MFS, CSS and OS rates were calculated using the Kaplan-Meier method. Descriptive analysis was also performed.

RESULTS

The median tumour size was 2.3 cm (range, 0.7-3.9 cm). The minimal and mean follow-up periods were 24 and 56 months, respectively. Local recurrence was detected in four patients (4.7%) at 8.5, 13.8, 58.0 and 64.0 months of follow-up and retreated successfully with percutaneous TA. No patient developed metastatic renal cell carcinoma, and none died due to renal oncologic complications. One patient died of heart attack. The 5-year LTPFS, OS, MFS and CSS rates were 93.0%, 98.4%, 100% and 100%, respectively. Only two patients (2.3%) had major complications (Clavien-Dindo grade > II), including ureteropelvic junction stenosis and urinary obstruction due to ureteral blood clots.

CONCLUSIONS

Our study demonstrates that percutaneous TA is a feasible and effective first-line therapy for healthy surgical candidates with small renal masses (T1a). The 5-year LTPFS, OS, CSS and MFS rates were 93.0%, 98.4%, 100% and 100%, respectively, with a major complication rate of only 2.3%.

KEY POINTS

• Image-guided percutaneous thermoablation of small renal malignancies was effective in 95.3% of the healthy surgical candidates. • Major complications were detected in 2.3% of the patients. • The local tumour progression-free survival rate was 97.6% and 93.0% at 3 and 5 years, respectively.

Functional and oncological outcome of percutaneous cryoablation versus laparoscopic partial nephrectomy for clinical T1 renal tumors: A propensity score-matched analysis

PURPOSE

To evaluate the clinical trifecta of percutaneous cryoablation (PCA) vs. laparoscopic partial nephrectomy (LPN) for cT1 renal tumors.

PATIENTS AND METHODS

We retrospectively analyzed the records of patients who had undergone 2 types of nephron sparing surgeries (NSS) PCA or LPN for cT1 renal tumors between November 2011 and December 2019. The cohorts were matched by one-to-one propensity scores based on patient demographics, renal function, and tumor complexity. Perioperative and oncological outcomes and preservation of renal function following surgery were compared.

RESULTS

After matching, a total of 180 patients who had undergone NSS for de novo renal tumors were evaluable: 90 for PCA and 90 for LPN. No statistically significant differences were noted among the measured baseline characteristics in the propensity score-matched cohorts. Overall perioperative complication rates were 5.5% in the PCA and 11.1% in the LPN groups (P = 0.28). The rate of eGFR preservation 1 to 3 months after surgery was significantly higher for PCA than for LPN (92.8 ± 11.5% vs. 88.5 ± 14.6%, P = 0.03). Median follow-up was 33 months for PCA and 18 months for LPN (P < 0.001). Three residual and 4 recurrent tumors were later diagnosed in the PCA group and 1 recurrent tumor in the LPN group. The 5-year local recurrence-free survival was lower for PCA than LPN (90.2% vs. 98.5%, P = 0.36). The 5-year metastasis-free survival rate was similar in both groups (98.4% vs. 100%, P = 0.38). The 5-year overall and cancer-specific survival rates were comparable in both groups (91.7% vs. 98.9%, P = 0.53, and 95% vs. 100%, P = 0.55, respectively).

CONCLUSIONS

Clinical T1 RCC patients are better treated with LPN if technically possible. Though PCA had a higher local recurrence rate, medium-term local control was not inferior to LPN. Additionally, PCA patients tended to retain renal function without severe complications. PCA appears to be a reasonable option for patients with high comorbidity at presentation.

Early trends and predictors of renal function following computed tomography-guided percutaneous cryoablation of a renal mass in patients with and without prior renal impairment

OBJECTIVE

To assess trends and predictors of the glomerular filtration rate (GFR) after renal mass cryoablation in patients with and without history of renal impairment.

MATERIALS AND METHODS

This was a retrospective study of 39 patients who underwent computed tomography-guided percutaneous cryoablation of a renal mass, divided into two groups: those with prior renal impairment (PRI+); and those without prior renal impairment (PRI-). The GFR trend and the chronic kidney disease stage were evaluated at baseline, as well as at 1, 6, and 12 months after cryoablation. Predictors of GFR at 1 and 6 months were modeled with linear regression.

RESULTS

In both groups, the mean GFR at 1 month and 6 months was significantly lower than at baseline (p < 0.001 and p = 0.01, respectively). Although the GFR was lower across all time points in the PRI+ group (-26.1; p < 0.001), the overall trend was not statistically different from that observed in the PRI- group (p = 0.89). Univariate analysis showed that the decline in GFR at 1 and 6 months correlated with the baseline GFR (0.77 and 0.63; p < 0.001 and p = 0.03, respectively) and with the size of the ablation zone (-7.6 and -12.84, respectively; p = 0.03 for both). However, in the multivariate model, baseline GFR was predictive only of GFR at 1 month (p < 0.001).

CONCLUSION

The trend in GFR decline after cryoablation is similar for patients with and without a history of renal impairment. Baseline GFR predicts the mean GFR in the early post-cryoablation period.

Systematic Review of Contemporary Evidence for the Management of T1 Renal Cell Carcinoma: What IRs Need to Know for Kidney Cancer Tumor Boards

Renal cell carcinoma is a relatively common malignancy, with 60 to 70 thousand cases a year in the United States alone. Increased utilization of cross-sectional imaging has led to an increase in the number of early renal cell cancers seen by the medical establishment. In addition, certain patient populations have an increased risk of developing kidney cancers which may mandate aggressive screening protocols. This article discusses the epidemiology of renal cell cancers; discusses the current management guidelines from multiple specialty societies; discusses some of the surgical and interventional techniques used in the treatment of such lesions; and provides a review of the literature regarding treatments of early-stage renal cell cancers.

Utilization of Stereotactic Ablative Body Radiation Therapy for Intact Renal Cell Carcinoma: Trends in Treatment and Predictors of Outcome

Purpose

Surgery is the standard-of-care treatment in patients with localized renal cell carcinoma (RCC), offering excellent chance of cure. However, there is a subset of patients who are ineligible for surgery and instead manage with ablative therapies, such as stereotactic ablative body radiation therapy (SABR). We used the National Cancer Database to examine trends in the use of SABR for inoperable RCC and identify any predictors of outcome.

Methods and Materials

We queried the National Cancer Database for patients with unresected RCC between 2004 and 2016 who were treated with SABR. Kaplan-Meier analyses were used to determine overall survival. Multivariable Cox regression was used to identify predictors of survival.

Results

We identified 347 patients meeting eligibility criteria. Median age was 74, and the majority of patients were clinical stage T1-2 (80%) and N0 (97%). The median tumor size was 3.8 cm (interquartile range [IQR], 2.8-5.2 cm). Six percent of patients received systemic therapy. The median dose of SABR was 45 Gy (IQR, 35-54 Gy) in 3 fractions (IQR, 1-5 fractions). The median follow-up was 36 months (IQR, 1-156 months). Predictors of decreased survival were age >74, larger tumors, and N1 or M1 disease. Median survival across the entire cohort was 58 months. Median survival was 92 months, 88 months, 44 months, and 26 months for primary tumors ≤2.5 cm, 2.6-3.5 cm, 3.5-5.0 cm, and >5.0 cm, respectively (P < .0001).

Conclusions

SABR is being increasingly used for renal cell carcinoma across the United States with excellent outcomes in smaller tumors.

Treatment Trends and Long-Term Survival Associated with Cryotherapy and Partial Nephrectomy for Small Renal Masses in the National Cancer Database Using Propensity Score Matching

Objective: Trends in the utilization of ablative therapy are unknown for the treatment of small renal masses. Our goal is to utilize the National Cancer Database (NCDB) to both assess the utilization of ablative therapies and long-term survival. Materials and Methods: The NCDB captures 70% of all cancer cases in the United States and was queried between 1998 and 2012 for renal cell carcinomas that were treated with ablative therapy, partial nephrectomy (PN), or radical nephrectomy. The analysis was limited to clinical stage T_1a. Propensity score matching was used in 1:1 fashion. Kaplan-Meier survival analysis and a Cox proportional hazards model were used to compare overall survival (OS) for cryotherapy and PN. Results: A total of 119,240 cases of clinical stage T_1a renal masses were treated between 1998 and 2012. Cryotherapy peaked at 927 (9.1%) cases in 2010 and had 913 (8.4%) in 2012. PN accounted for 18% of the cases in 1998, but surpassed the utilization of nephrectomy in 2008. By 2012, PN accounted for 6766 (62%) of renal mass cases. After matching, Kaplan-Meier OS was lower for cryotherapy compared with PN at 24 (94.5% vs 96.5%), 48 (86.8% vs 90.9%), and 96 months (66.0% vs 74.9%). Cryotherapy also had a lower OS (hazard ratio 1.46; p < 0.001) on adjusted analysis. Conclusion: Cryotherapy for small renal masses plateaued at 9% utilization in 2009. Cryotherapy had a lower OS than PN for tumors >2 cm on adjusted analysis, but this result should be used with caution until confirmed in randomized studies.

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.

Metanephric adenoma with low apparent diffusion coefficient value mimicking renal cell carcinoma: A case report

RATIONALE

Metanephric adenoma (MA) is a rare and often benign tumor. Most MAs were misdiagnosed as renal cell carcinomas (RCCs) preoperatively. Diffusion weighted imaging (DWI) and apparent diffusion coefficient (ADC) mapping can help to differentiate benign and malignant tumors. However, there are still pitfalls in using DWI and ADC to discriminate benign and malignant lesions.

PATIENT CONCERNS

A 56-year-old woman had a right renal metanephric adenoma. The tumor showed very low ADC value preoperatively and was misdiagnosed as a renal cell carcinoma.

DIAGNOSIS

Intraoperative ultrasound-guided percutaneous biopsy of tumor was performed. Based on the histopathological findings and immunohistochemical stains, a diagnosis of metanephric adenoma was suggested.

INTERVENTIONS

The patient received percutaneous cryoablation of this tumor. Five years later, she underwent right partial nephrectomy because local recurrence was revealed on a follow-up computed tomography (CT).

OUTCOMES

MA was confirmed again by histological examination. The patient was uneventful after surgery.

LESSONS

ADC mapping can be used for differentiating RCCs from other benign tumors by their lower ADC values. However, some benign and malignant lesions have overlapped low ADC values. This case illustrated that a benign lesion such as MA could mimic RCC on ADC, by its highly cellular component. Cryoablation is an optional treatment, which has an increased risk of local recurrence. Follow-up CT or MRI is useful and necessary for detection of local recurrence by depicting enhancing solid parts in a tumor over time.

Focal therapy versus robot-assisted partial nephrectomy in the management of clinical T1 renal masses: A systematic review and meta-analysis

BACKGROUND

Robot-assisted partial nephrectomy (RPN) and focal therapy (FT) have both been successfully employed in the management of small renal masses. However, despite this being the era of minimally invasive surgery, few comparative studies exist on RPN and FT. The aim of our study is to review perioperative, renal functional and oncologic outcomes of FT and RPN in cT1 renal masses.

METHODS

Literature published in Medline, EMBASE, and Cochrane Library databases up to April 22, 2018, was systematically searched. We included literature comparing outcomes of FT (radiofrequency ablation, cryoablation, microwave ablation, and irreversible electroporation) and RPN. Studies that reported only on laparoscopic partial nephrectomy or open partial nephrectomy, and review articles, editorials, letters, or cost analyses were excluded. In total, data from 1166 patients were included.

RESULTS

From 858 total articles, 7 nonrandomized, observational studies were included. Compared with RPN, FT was associated with a significantly lower decrease of estimated glomerular filtration rate (weighted mean difference [WMD] -8.06 mL/min/1.73 m; confidence interval [CI] -15.85 to -0.26; P = .04), and lower estimated blood loss (WMD -49.61 mL; CI -60.78 to -38.45; P < .001). However, patients who underwent FT had a significantly increased risk of local recurrence (risk ratio [RR] 9.89; CI 4.24-23.04; P < .001) and distant metastasis (RR 6.42; CI 1.70-24.33; P = .006). However, operative times, lengths of stay, and complication rates were revealed to be similar between FT and RPN.

CONCLUSION

RPN has a substantial advantage in preventing cancer recurrence. However, in the era of minimally invasive surgery, FT has advantages in renal function preservation and less bleeding. Long-term follow-up for survival rates and comparative analysis of microwave ablation and irreversible electroporation are needed to extend FT for patients with significant morbidities and for those who need sufficient renal function preservation with minimal bleeding.

Peri-operative and local control outcomes of robot-assisted partial nephrectomy vs percutaneous cryoablation for renal masses: comparison after matching on radiological stage and renal score

OBJECTIVES

To compare the oncological outcomes of percutaneous cryoablation (PCA) vs robot-assisted partial nephrectomy (RAPN) for the treatment of T1 renal tumours.

PATIENTS AND METHODS

We conducted a retrospective study in all patients treated by RAPN or PCA for malignant renal tumours in one of four centres between 2009 and 2016. Tumours were paired one by one using radiological tumour stage and RENAL nephrometry score (package matchit, R software version 3.2.2). Malignancy was confirmed by biopsy for all patients in the PCA group. Patient characteristics before and after matching and oncological results were compared between the two groups. Cox regression, adjusted for age, treatment type, histological type and margins, was used to identify factors associated with time to local recurrence. Positive margins were defined histologically in the RAPN group and radiologically in the PCA group.

RESULTS

A total of 647 patients were identified; 470 underwent RAPN and 177 underwent PCA. After matching, there was no significant difference between the two groups (RAPN, n = 177; PCA, n = 177) with regard to tumour stage, RENAL nephrometry score, tumour size (27.6 vs 25.9 mm; P = 0.07) and gender ratio. Patients in the PCA group remained significantly older (69.9 vs 59.8 years; P < 0.001). The absolute recurrence rate was 2.8% in the RAPN group vs 8.4% in the PCA group (P = 0.03). The 5-year recurrence-free survival rate was 85% in the PCA group vs 95% in the RAPN group (log-rank P = 0.02). In multivariate analysis, the presence of positive margins and the type of treatment were the two factors significantly associated with local recurrence (P < 0.001 and P = 0.046, respectively).

CONCLUSION

The local recurrence rate after PCA was significantly higher than after RAPN for T1 renal tumours. Incomplete treatment was the main criterion associated with recurrence. The recurrence rate may have been overestimated in the PCA group because of closer radiological follow-up in these patients.

Partial nephrectomy versus ablative techniques for small renal masses: a systematic review and network meta-analysis

PURPOSE

To compare partial nephrectomy (PN), radiofrequency ablation (RFA), cryoablation (CRA) and microwave ablation (MWA) regarding oncologic, perioperative and functional outcomes.

MATERIAL AND METHODS

The MEDLINE, EMBASE and COCHRANE libraries were searched for studies comparing PN, RFA, CRA or MWA and reporting on any-cause or cancer-specific mortality, local recurrence, complications or renal function. Network meta-analyses were performed.

RESULTS

Forty-seven studies with 24,077 patients were included. Patients receiving RFA, CRA or MWA were older and had more comorbidities compared with PN. All-cause mortality was higher for CRA and RFA compared with PN (incidence rate ratio IRR = 2.58, IRR = 2.58, p < 0.001, respectively). No significant differences in cancer-specific mortality were evident. Local recurrence was higher for CRA, RFA and MWA compared with PN (IRR = 4.13, IRR = 1.79, IRR = 2.52, p < 0.05 respectively). A decline in renal function was less pronounced after RFA versus PN, CRA and MWA (mean difference in GFR MD = 6.49; MD = 5.82; MD = 10.89, p < 0.05 respectively).

CONCLUSION

Higher overall survival and local control of PN compared with ablative therapies did not translate into significantly better cancer-specific mortality. Most studies carried a high risk of bias by selecting younger and healthier patients for PN, which may drive superior survival and local control. Physicians should be aware of the lack of high-quality evidence and the potential benefits of ablative techniques for certain patients, including a superior complication profile and renal function preservation.

KEY POINTS

• Patients selected for ablation of small renal masses are older and have more comorbidities compared with those undergoing partial nephrectomy. • Partial nephrectomy yields lower all-cause mortality, which is probably biased by patient selection and does not translate into prolonged cancer-free survival. • The decline of renal function is smallest after radiofrequency ablation for small renal masses.

Is Cryotherapy a Genuine Rival to Robotic-assisted Partial Nephrectomy in the Management of Suspected Renal Malignancy? A Systematic Review and Meta-analysis

We systematically reviewed the world literature and compare oncological outcomes, morbidity, renal function, and perioperative outcome between cryotherapy and robotic-assisted partial nephrectomy (RAPN) for suspected renal malignancy. There was a statistically significant difference in "recurrence rates" between the 2 techniques, favoring the RAPN cohort. There was no statistically significant difference in overall and ≥Clavien 3a complication rates between the 2 techniques. The quality of evidence for recurrence rates, overall complication, and ≥Clavien 3a were "moderate", "low," and "very low," respectively, on GRADE (Grading of Recommendations Assessment, Development and Evaluation) approach. If a nephron sparing approach is indicated, RAPN should be the approach of choice.

Comparisons of percutaneous versus retroperitoneoscopic cryoablation for renal masses

PURPOSE

Preserving renal function and controlling oncological outcomes are pertinent while managing renal tumours. We compared outcomes of percutaneous cryoablation (PCA) and retroperitoneoscopic cryoablation (RCA) in patients with renal neoplasms.

METHODS

We identified 108 patients with renal tumours at two medical centres, where 63 patients received PCA and 45 patients underwent RCA from August 2009 to July 2015, and they were followed up until February 2017. We compared preoperative and postoperative parameters, namely gender, systemic diseases, age, American Society of Anesthesiologists score, body mass index (BMI), haemoglobin, the estimated glomerular filtration rate, tumour size, operative time, tumour type, Clavien-Dindo classification of surgical complications, and tumour recurrence, by using an independent sample t test, Pearson's Chi-square test, Fisher's exact test, a Mann-Whitney test, and a generalised linear model.

RESULTS

Based on baseline characteristics, we found that the patients in the PCA group were older and had higher BMI than those in the RCA group, whereas the patients in the RCA group had more comorbidities than those in the PCA group. Retroperitoneoscopic and percutaneous methods had similar operative times, blood transfusion rates, postoperative fever episodes, and complication rates for either minor or major complications. However, the percutaneous method was associated with a shorter length of stay. No patient experienced deterioration in renal function until 2 years after both procedures. Impaired renal function was found in both groups in the 3-year follow-up. In both groups, tumour recurrence was significant for tumours > 4 cm.

CONCLUSIONS

Our results confirm that both cryoablation methods (PCA and RCA) are safe and effective for renal cell carcinoma. Favourable oncological control was achieved in both groups if the renal tumour size was ≤ 4 cm.

Partial Nephrectomy versus Thermal Ablation for Clinical Stage T1 Renal Masses: Systematic Review and Meta-Analysis of More than 3,900 Patients

PURPOSE

A systematic review and meta-analysis of clinical trials was undertaken to compare percutaneous thermal ablation versus partial nephrectomy (PN) for stage T1 renal tumors.

MATERIALS AND METHODS

A comprehensive search of major databases was conducted from October 2000 to July 2016. Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines were followed. Incidences of all-cause mortality (ACM), cancer-specific mortality (CSM), local recurrence (LR), and metastases, as well as complication rates and changes in estimated glomerular filtration rate (eGFR), were evaluated.

RESULTS

Inclusion criteria were met by 15 of 961 papers. These studies represented 3,974 patients who had undergone an ablative procedure (cryoablation or radiofrequency ablation; n = 1,455; 37%) or PN (n = 2,519; 63%). ACM and CSM rates were higher for ablation than for PN (hazard ratio [HR], 2.11; 95% confidence interval [CI], 1.54-2.87 [P < .05]; HR, 3.84; 95% CI, 1.66-8.88 [P < .05], respectively). No statistically significant difference in LR rate or risk of metastasis was seen between ablation and PN (HR, 1.32; 95% CI, 0.79-2.22 [P = .22]; HR, 1.83; 95% CI, 0.67-5.01 [P = 0.23], respectively). Complication rates were lower for ablation than for PN (13% vs 17.6%; odds ratio, 0.49; 95% CI, 0.25-0.94; P < .05). A significantly greater decrease in eGFR was observed after PN (13.09 mL/min/1.73 m²) vs ablation therapy (4.47 mL/min/1.73 m²).

CONCLUSIONS

Thermal ablation showed no significant difference in LR or metastases compared with PN. Thermal ablation was associated with a lower morbidity rate and a lesser reduction in eGFR compared with PN, but with higher ACM and CSM rates.

SEER study of ablation versus partial nephrectomy in cT1A renal cell carcinoma

Aim: Compare ablation versus partial nephrectomy (PN) in T1A renal cell carcinoma (RCC) treatment, using the SEER database. Methods: Patients with diagnosed T1A RCC from 2004 to 2013 were identified. Propensity matching paired subjects with similar background variables. Kaplan–Meier and Cox proportional hazards regression were performed before and after matching. Results: Cohort included 4592 patients (809 ablation, 3783 PN). PN compared with ablation group had significantly increased overall survival (OS; 93.6% vs 81.9% 5-year survival; p < 0.0001) and cancer-specific survival (CSS; p < 0.0001). After matching (1222 pairs), PN group had significantly increased OS (91.0% vs 86.3% 5-year survival; p = 0.0457) but similar CSS (p = 0.4023). Conclusion: Ablation offers similar CSS but lower OS as PN for T1A RCC in this SEER database.

Renal Cell Carcinoma in von Hippel-Lindau Disease-From Tumor Genetics to Novel Therapeutic Strategies

von Hippel-Lindau (VHL) disease is an autosomal dominant syndrome caused by mutations in the VHL tumor-suppressor gene, leading to the dysregulation of many hypoxia-induced genes. Affected individuals are at increased risk of developing recurrent and bilateral kidney cysts and dysplastic lesions which may progress to clear cell renal cell carcinoma (ccRCC). Following the eponymous VHL gene inactivation, ccRCCs evolve through additional genetic alterations, resulting in both intratumor and intertumor heterogeneity. Genomic studies have identified frequent mutations in genes involved in epigenetic regulation and phosphoinositide 3-kinase-AKT-mechanistic target of rapamycin (mTOR) pathway activation. Currently, local therapeutic options include nephron-sparing surgery and alternative ablative procedures. For advanced metastatic disease, systemic treatment, including inhibition of vascular endothelial growth factor pathways and mTOR pathways, as well as immunotherapy are available. Multimodal therapy, targeting multiple signaling pathways and/or enhancing the immune response, is currently being investigated. A deeper understanding of the fundamental biology of ccRCC development and progression, as well as the development of novel and targeted therapies will be accelerated by new preclinical models, which will greatly inform the search for clinical biomarkers for diagnosis, prognosis, and response to treatment.

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.

Focal ablation therapy for renal cancer in the era of active surveillance and minimally invasive partial nephrectomy

Partial nephrectomy is the optimal surgical approach in the management of small renal masses (SRMs). Focal ablation therapy has an established role in the modern management of SRMs, especially in elderly patients and those with comorbidities. Percutaneous ablation avoids general anaesthesia and laparoscopic ablation can avoid excessive dissection; hence, these techniques can be suitable for patients who are not ideal surgical candidates. Several ablation modalities exist, of which radiofrequency ablation and cryoablation are most widely applied and for which safety and oncological efficacy approach equivalency to partial nephrectomy. Data supporting efficacy and safety of ablation techniques continue to mature, but they originate in institutional case series that are confounded by cohort heterogeneity, selection bias, and lack of long-term follow-up periods. Image guidance and surveillance protocols after ablation vary and no consensus has been established. The importance of SRM biopsy, its optimal timing, the type of biopsy used, and its role in treatment selection continue to be debated. As safety data for active surveillance and experience with minimally invasive partial nephrectomy are expanding, the role of focal ablation therapy in the treatment of patients with SRMs requires continued evaluation.

[Ablative therapy in kidney cancer: Oncological, functional, perioperative outcomes and cost]

INTRODUCTION

The incidence of kidney cancer has increased significantly over the past few decades presumably due to the increased use of imaging. The aim of this article is to describe contemporary outcomes of ablative therapy and to compare them to other therapeutic options in terms of oncological, functional, perioperative outcomes and cost.

MATERIAL AND METHODS

We searched MEDLINE^®, Embase^®, using (MeSH) words; from January 2005 through May 2017, and we looked for all the studies. Investigators graded the strength of evidence in terms of methodology, language and relevance.

RESULTS

Ninety-one articles were analyzed. We described the outcomes of ablative therapy in relation to the energy used and the approach, and compared these outcomes to the other therapeutic options in terms of oncological, functional and perioperative outcomes. We analyzed these studies in order to search for predictive factors influencing the results of ablative therapy. We also analyzed the economic burden of small renal tumor management.

CONCLUSION

The strength of evidence is based almost entirely on retrospective studies and is susceptible to the inherent limitations of this study design. Although, the evidence was low among studies, our revue showed that, in elderly patients treated with ablative therapy for cT1a tumors, the cancer-specific survival was comparable to partial nephrectomy with differences in overall survival that are explained by competing risks of death in the old population. Considering the functional results, the renal function preservation seems to be comparable between the 2 groups while the perioperative morbidity is higher in the partial nephrectomy group. The evidence base medicine at this time cannot support the extension of the indications of ablative therapy beyond the actual implementations.

Renal Cell Carcinoma: Alternative Nephron-Sparing Treatment Options for Small Renal Masses, a Systematic Review

BACKGROUND

The standard treatment of T1 renal cell carcinoma (RCC) is (partial) nephrectomy. For patients where surgery is not the treatment of choice, for example in the elderly, in case of severe comorbidity, inoperability, or refusal of surgery, alternative treatment options are available. These treatment options include active surveillance (AS), radiofrequency ablation (RFA), cryoablation (CA), microwave ablation (MWA), or stereotactic body radiotherapy (SBRT). In the present overview, the efficacy, safety, and outcome of these different options are summarized, particularly focusing on recent developments.

MATERIALS AND METHODS

Databases of MEDLINE (through PubMed), EMBASE, and the Cochrane Library were systematically searched according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) criteria. The search was performed in December 2016, and included a search period from 2010 to 2016. The terms and synonyms used were renal cell carcinoma, active surveillance, radiofrequency ablation, microwave ablation, cryoablation and stereotactic body radiotherapy.

RESULTS

The database search identified 2806 records, in total 73 articles were included to assess the rationale and clinical evidence of alternative treatment modalities for small renal masses. The methodological quality of the included articles varied between level 2b and level 4.

CONCLUSION

Alternative treatment modalities, such as AS, RFA, CA, MWA, and SBRT, are treatment options especially for those patients who are unfit to undergo an invasive treatment. There are no randomized controlled trials available comparing surgery and less invasive modalities, leading to a low quality on the reported articles. A case-controlled registry might be an alternative to compare outcomes of noninvasive treatment modalities in the future.

Renal Functional Outcomes after Surgery, Ablation, and Active Surveillance of Localized Renal Tumors: A Systematic Review and Meta-Analysis

BACKGROUND AND OBJECTIVES

Management strategies for localized renal masses suspicious for renal cell carcinoma include radical nephrectomy, partial nephrectomy, thermal ablation, and active surveillance. Given favorable survival outcomes across strategies, renal preservation is often of paramount concern. To inform clinical decision making, we performed a systematic review and meta-analysis of studies comparing renal functional outcomes for radical nephrectomy, partial nephrectomy, thermal ablation, and active surveillance.

DESIGN, SETTINGS, PARTICIPANTS, & MEASUREMENTS

We searched MEDLINE, Embase, and the Cochrane Central Register of Controlled Trials from January 1, 1997 to May 1, 2015 to identify comparative studies reporting renal functional outcomes. Meta-analyses were performed for change in eGFR, incidence of CKD, and AKI.

RESULTS

We found 58 articles reporting on relevant renal functional outcomes. Meta-analyses showed that final eGFR fell 10.5 ml/min per 1.73 m2 lower for radical nephrectomy compared with partial nephrectomy and indicated higher risk of CKD stage 3 or worse (relative risk, 2.56; 95% confidence interval, 1.97 to 3.32) and ESRD for radical nephrectomy compared with partial nephrectomy. Overall risk of AKI was similar for radical nephrectomy and partial nephrectomy, but studies suggested higher risk for radical nephrectomy among T1a tumors (relative risk, 1.37; 95% confidence interval, 1.13 to 1.66). In general, similar findings of worse renal function for radical nephrectomy compared with thermal ablation and active surveillance were observed. No differences in renal functional outcomes were observed for partial nephrectomy versus thermal ablation. The overall rate of ESRD was low among all management strategies (0.4%-2.8%).

CONCLUSIONS

Renal functional implications varied across management strategies for localized renal masses, with worse postoperative renal function for patients undergoing radical nephrectomy compared with other strategies and similar outcomes for partial nephrectomy and thermal ablation. Further attention is needed to quantify the changes in renal function associated with active surveillance and nephron-sparing approaches for patients with preexisting CKD.

Safety and feasibility of radiofrequency ablation for treatment of Bosniak IV renal cysts

Purpose

To describe our initial experience with radiofrequency ablation (RFA) of Bosniak IV renal cysts.

Materials and Methods

From 2010 to 2014, 154 renal tumor cases were treated with percutaneous thermal ablation, of which 10 cases (6.4%) from nine patients were complex renal cysts and were treated with radiofrequency ablation.

Results

All complex cysts were classified as Bosniak IV (four women and five men; mean age: 63.6 yrs, range: 33–83 years). One patient had a single kidney. Lesion size ranged from 1.5 to 4.1cm (mean: 2.5cm) and biopsy was performed on four cysts immediately before the procedure, all of which were malignant (two clear cell and two papillary carcinoma). Mean volume reduction of complex cysts was 25% (range: 10–40%). No patients required retreatment with RFA and no immediate or late complications were observed. The follow-up of Bosniak IV cysts had a median of 27 months (interquartile range [IQR], 23 to 38) and no recurrence or significant loss of renal function were observed.

Conclusions

Mid-term follow-up of the cases in our database suggests that image-guided percutaneous RFA can treat Bosniak IV cysts with very low complication rates and satisfactorily maintain renal function.

Image-guided ablation of renal cell carcinoma

This review article aims to provide an overview of image-guided ablation of renal cell carcinoma (RCC) since it was first introduced in 1998. This will cover the background and rationale behind its development; an overview of the evidence for current thermal technology, such as heat-based, e.g., radiofrequency ablation (RFA), microwave ablation (MWA), and cold-based energies, e.g., cryoablation used; and summarise the published evidence regarding its treatment efficacy and oncological outcome. In addition, it aims to provide an insight into the potential role of the new non-thermal ablative technology, e.g., irreversible electroporation (IRE)/Nanoknife in image-guided ablation of RCC, as well as areas of challenge that will require further research and clinical evaluation to ensure delivery of a quality patient-centred interventional oncology (IO) service in image-guided ablation of RCC.

Management of Small Renal Masses: American Society of Clinical Oncology Clinical Practice Guideline

Purpose To provide recommendations for the management options for patients with small renal masses (SRMs). Methods By using a literature search and prospectively defined study selection, we sought systematic reviews, meta-analyses, randomized clinical trials, prospective comparative observational studies, and retrospective studies published from 2000 through 2015. Outcomes included recurrence-free survival, disease-specific survival, and overall survival. Results Eighty-three studies, including 20 systematic reviews and 63 primary studies, met the eligibility criteria and form the evidentiary basis for the guideline recommendations. Recommendations On the basis of tumor-specific findings and competing risks of mortality, all patients with an SRM should be considered for a biopsy when the results may alter management. Active surveillance should be an initial management option for patients who have significant comorbidities and limited life expectancy. Partial nephrectomy (PN) for SRMs is the standard treatment that should be offered to all patients for whom an intervention is indicated and who possess a tumor that is amenable to this approach. Percutaneous thermal ablation should be considered an option if complete ablation can reliably be achieved. Radical nephrectomy for SRMs should only be reserved for patients who possess a tumor of significant complexity that is not amenable to PN or for whom PN may result in unacceptable morbidity even when performed at centers with expertise. Referral to a nephrologist should be considered if chronic kidney disease (estimated glomerular filtration rate < 45 mL/min/1.73 m²) or progressive chronic kidney disease occurs after treatment, especially if associated with proteinuria.

Management of Renal Masses and Localized Renal Cancer: Systematic Review and Meta-Analysis

PURPOSE

Several options exist for management of clinically localized renal masses suspicious for cancer, including active surveillance, thermal ablation and radical or partial nephrectomy. We summarize evidence on effectiveness and comparative effectiveness of these treatment approaches for patients with a renal mass suspicious for localized renal cell carcinoma.

MATERIALS AND METHODS

We searched MEDLINE®, Embase® and the Cochrane Central Register of Controlled Trials from January 1, 1997 through May 1, 2015. Paired investigators independently screened articles to identify controlled studies of management options or cohort studies of active surveillance, abstracted data sequentially and assessed risk of bias independently. Strength of evidence was graded by comparisons.

RESULTS

The search identified 107 studies (majority T1, no active surveillance or thermal ablation stratified outcomes of T2 tumors). Cancer specific survival was excellent among all management strategies (median 5-year survival 95%). Local recurrence-free survival was inferior for thermal ablation with 1 treatment but reached equivalence to other modalities after multiple treatments. Overall survival rates were similar among management strategies and varied with age and comorbidity. End-stage renal disease rates were low for all strategies (0.4% to 2.8%). Radical nephrectomy was associated with the largest decrease in estimated glomerular filtration rate and highest incidence of chronic kidney disease. Thermal ablation offered the most favorable perioperative outcomes. Partial nephrectomy showed the highest rates of urological complications but overall rates of minor/major complications were similar among interventions. Strength of evidence was moderate, low and insufficient for 11, 22 and 30 domains, respectively.

CONCLUSIONS

Comparative studies demonstrated similar cancer specific survival across management strategies, with some differences in renal functional outcomes, perioperative outcomes and postoperative harms that should be considered when choosing a management strategy.

Cryoablation of small kidney tumors

INTRODUCTION

Cryoablation (CA) has been broadly used mostly in the treatment of small renal masses (SRMs). The present review aims to define the current role of CA in the treatment of SRMs by assessing clinical indications and outcomes.

METHOD

A comprehensive review on patient selection, procedural details, perioperative complications, and short/long-term oncological and functional outcomes was conducted. For each section, a take-home message was formulated with level of evidence (LoE) according to Cochrane collaboration.

RESULTS

Age and comorbidity drive the choice of ablation in SRMs, although hospital setting also influences the decision. Technically in adequate CA or first post-CA control occurs in 3-5% of laparoscopic cryoablation (LCA) or percutaneous cryoablation (PCA) series. Meta-analysis does not evidence differences in the rate of residual tumor per person-year between the approaches (0.033 LCA vs. 0.046 PCA, p = 0.25). Perioperative complications (8-25%) are erratically reported. LCA has significantly lower likelihood of complications than minimally invasive partial nephrectomy (MIPN). Systematic reviews indicate 30-month local tumor progression rate of 8.5% for LCA in renal cell carcinoma but low metastatic progression (1-4.4%). Few LCA long-term follow-up series (mean/media 48-98 months) report recurrence-free survival (RFS) and cancer-specific survival (CSS) ranges of 80-100%. For PCA, Kaplan-Meier local disease-free survival (DFS) of 95.6% at 3-5 years [32] and 5-year overall survival and local RFS of 86.3% were reported. The decrease in renal function after CA is minimal, and the only risk factor associated is the basal estimated glomerular filtration rate (eGFR).

CONCLUSION

LoE 3a/b confirms lower CA perioperative complication rate and higher local progression rate than those for MIPN. CA preserves postoperative renal functional, without any evidence of differences in mid-/long-term follow-up compared to nephron sparing surgery.

Evolutionary magnetic resonance appearance of renal cell carcinoma after percutaneous cryoablation

Objective:

To determine the evolutionary MRI appearance of renal cell carcinoma (RCC) following cryoablation.

Methods:

For this institution review board-approved study, we recruited patients with biopsy-proven RCC and treated them with percutaneous cryoablation between November 2009 and October 2014. Two radiologists retrospectively reviewed the pre-procedural and follow-up MRI. The findings included tumour sizes, signal intensities on T₁ weighted imaging (T1WI), T₂ weighted imaging (T2WI), diffusion-weighted imaging, apparent diffusion coefficient (ADC) map and contrast enhancement patterns. The ADC values of the tumours before and after treatment were measured.

Results:

A total of 26 patients were enrolled. The ablated tumours exhibited predominantly high signals on T1WI at 1–9-month follow-up (47.1% strong hyperintense at 3 months) and subsequently returned to being isointense. In T2WI, the signals of the ablated tumours were highly variable during the first 3 months and became strikingly hypointense after 6 months (58.3% strong hypointense at 6 months). Diffusion restriction was prominent during the first 3 months (lowest ADC: 0.62 ± 0.29 × 10⁻³ mm² s⁻¹ at 1 month). Contrast enhancement persisted up to 6 months after the procedure. The residual enhancement gradually increased in the dynamic scan and was most prominent in the delay phase.

Conclusion:

The MRI of the cryoablated renal tumour follows a typical evolutionary pattern.

Advances in knowledge:

Familiarity of practitioners with the normal post-cryoablation change of RCC on MRI can enable the early detection and prevention of tumour recurrence.

Modeling Cryotherapy Ice Ball Dimensions and Isotherms in a Novel Gel-based Model to Determine Optimal Cryo-needle Configurations and Settings for Potential Use in Clinical Practice

Objective

To gain a better understanding of ice ball dimensions and temperature isotherms relevant for cell kill when using combinations of cryo-needles we set out to answer 4 questions: (1) what type of cryo-needle? (2) how many needles? (3) best spatial configuration? and (4) correct duty cycle percentage?

Methods

We conducted laboratory experiments to monitor ice ball dimensions and create multi-needle planar isotherm maps for 17G and 10G cryo-needles using a novel multi-needle thermocouple fixture within gel at body temperature. We tested configurations of 1-4 cryo-needles at duty cycles of 20%-100% with 1-2.5 cm spacing.

Results

Analysis of various combinations shows that a central core of ≤−40°C develops at a distance of ~1 cm around the cryo-needles. Temperature increases linearly from this point to the ice ball leading edge (0°C), which is a further ≈1 cm away. Thus, the −40°C isotherm is approximately 1 cm inside the leading edge of the ice ball.

The optimum distance between cryo-needles was 1.5-2 cm, at duty cycle settings of 70%-100%. At distances further apart or with lower duty cycle settings, ice balls either had a central core >−40°C or had an hourglass shape.

Conclusion

In answer to questions 1-3, tumor length, diameter, and shape will ultimately determine the number of needles and their configuration. However, we propose a conservative distance for cryo-needle placement between 1 and 1.5 cm should be adopted for clinical practice. In answer to question 4, using low duty cycle settings runs the risk of incomplete −40°C isotherm coverage of the tumor, and thus in routine practice we suggest that settings of 70%-100% are most appropriate.

Emerging surgical treatments for renal cell carcinoma

Treatment of renal cell carcinoma has evolved considerably over the last few years. While total nephrectomy is necessary at times, nephron-sparing surgery, with a goal of renal function preservation, should always be considered. Although open partial nephrectomy is considered the gold standard approach for nephron-sparing surgery, laparoscopic- or robotic-assisted techniques allow urologists to perform renal surgery less invasively, with excellent long-term oncological outcomes. Cryotherapy and radiofrequency ablation are less invasive management approaches for carefully selected patients with small renal masses. Active surveillance should be considered in elderly or patients who are unfit for surgery. Ultimately, the method chosen for management of a renal mass is an informed decision made by the physician and patient.

Urinary fistula after robot-assisted partial nephrectomy: a multicentre analysis of 1 791 patients

OBJECTIVE

To evaluate the incidence of and risk factors for a urine leak in a large multicentre, prospective database of robot-assisted partial nephrectomy (RPN).

PATIENTS AND METHODS

A database of 1 791 RPN from five USA centres was reviewed for urine leak as a complication of RPN. Patient and tumour characteristics were compared between patients with and those without postoperative urine leaks. Fisher's exact test was used for qualitative variables and Wilcoxon sum-rank tests were used for quantitative variables. A review of the literature on PN and urine leak was conducted.

RESULTS

Urine leak was noted in 14/1 791 (0.78%) patients who underwent RPN. The mean (sd) nephrometry score of the entire cohort was 7.2 (1.9), and 8.0 (1.9) in patients who developed urine leak. The median (range) postoperative day of presentation was 13 (3-32) days. Patients with urine leak presented in delayed fashion with fever (two of the 14 patients, 14%), gastrointestinal complaints (four patients, 29%), and pain (five patients, 36%). Eight of the 14 patients (57%) required admission, while eight (57%) and nine (64%) had a drain or stent placed, respectively. Drains and stents were removed after a median (range) of 8 (4-13) days and 21 (8-83) days, respectively. Variables associated with urine leak included tumour size (P = 0.021), hilar location (P = 0.025), operative time (P = 0.006), warm ischaemia time (P = 0.005), and pelvicalyceal repair (P = 0.018). Upon literature review, the historical incidence of urine leak ranged from 1.0% to 17.4% for open PN and 1.6-16.5% for laparoscopic PN.

CONCLUSION

The incidence of urine leak after RPN is very low and may be predicted by some preoperative factors, affording better patient counselling of risks. The low urinary leak rate may be attributed to the enhanced visualisation and suturing technique that accompanies the robotic approach.

National Trends of Local Ablative Therapy Among Young Patients With Small Renal Masses in the United States

OBJECTIVE

To assess national trends in the usage of local ablative therapy for small renal masses (SRMs) in a cohort of young patients. Ablation of SRMs has been shown to offer cancer control with limited follow-up. Although ablation is considered effective for patients with limited life expectancy, its use among younger patients may be considered controversial.

METHODS

We used the National Cancer Data Base to identify patients between the ages of 40 and 65 years who were diagnosed with SRMs from 2004 to 2011. The primary outcome was the use of local ablative therapy. Multivariable logistic regression analysis was used to identify patient and hospital factors associated with ablation therapies in this cohort.

RESULTS

During the study period, we identified 49,441 patients with SRMs, of which 2789 (5.6%) were treated with ablative therapies. The proportion of patients undergoing ablation gradually rose from 2.2% in 2004 to 6.2% in 2011 (P < .001). On multivariable analysis, patients were more likely to receive local ablation at academic hospitals (odds ratio [OR]: 1.5; P < .001) compared with community hospitals, or primarily insured by Medicaid (OR: 1.4; P < .001) or Medicare (OR: 1.3; P < .001) compared with private insurance.

CONCLUSION

The use of local ablative therapies is gradually rising but has so far been limited to a small fraction of young patients with SRMs. Patients treated at high-volume, academic hospitals or insured with Medicaid or Medicare were treated to a greater degree with ablation. These results have important implications for the adoption of ablation and the need for long-term surveillance.

Radiation Exposure During Percutaneous Ablation of Small Renal Masses: A Multi-Institutional Multimodality Analysis

OBJECTIVE

To understand the effective radiation dose during percutaneous cryoablation (CA) and radiofrequency ablation (RFA) and characterize variables that may affect the individual dose.

MATERIALS AND METHODS

The effective radiation dose was determined by conversion of the dose-length product from CT scans performed during percutaneous CA or RFA for patients with solitary renal masses (<4 cm) at four academic centers. Radiation dose per case was compared between patients and institutions using multivariate and univariate analysis. Lifetime attributable risk of cancer was calculated for each institution and utilized to determine the number needed to harm for a range of ages at the time of exposure.

RESULTS

One hundred twenty-three patients met the inclusion criteria with a mean age of 71 years. Sixty-nine percent of patients were male, mean body-mass index (BMI) was 29.4, and mean tumor size was 2.2 cm. The mean effective radiation dose per ablation was 40 mSv (range 3.7-147). On multivariate analysis, only BMI and institution were associated with the radiation dose. No significant difference in radiation exposure was seen for RFA or CA procedures.

CONCLUSIONS

Radiation exposure during percutaneous ablation is similar to a multiphase CT scan. However, there is wide variability in individual treatment exposure, varying from 3.7 to 147 mSv, depending primarily on institution and BMI. Standardization of protocols is required to achieve as low as reasonably achievable levels of radiation.

Thermal ablation in renal cell carcinoma management: a comprehensive review

PURPOSE OF REVIEW

This article provides an overview of recent developments in the field of thermal ablation for renal cell carcinoma and focuses on current standard techniques, new technologies, imaging for ablation guidance and evaluation, and future perspectives.

RECENT FINDINGS

Emerging long-term data on cryoablation and radiofrequency ablation (RFA) show marginally lower oncologic outcomes compared to surgical treatment, balanced by better functional and perioperative outcomes. Reports on residual disease vary widely, influenced by different definitions and strategies in determining ablation failure. Stratifying disease-free survival after RFA according to tumor size suggests 3 cm to be a reasonable cut off for RFA tumor selection. Microwave ablation and high-intensity focal ultrasound are modalities with the potential of creating localized high temperatures. However, difficulties in renal implementation are impairing sufficient ablation results. Irreversible electroporation, although not strictly thermal, is a new technology showing promising results in animal and early human research.

SUMMARY

Although high-level randomized controlled trials comparing thermal ablation techniques are lacking, evidence shows that thermal ablation for small renal masses is a safe procedure for both long-term oncologic and functional outcomes. Thermal ablation continues to be associated with a low risk of residual disease, for which candidates should be properly informed. RFA and cryoablation remain the standard techniques whereas alternative techniques require further studies.

Comparison of partial nephrectomy and percutaneous ablation for cT1 renal masses

BACKGROUND

Partial nephrectomy (PN) is a preferred treatment for cT1 renal masses, whereas thermal ablation represents an alternative nephron-sparing option, albeit with higher reported rates of recurrence.

OBJECTIVE

To review our experience with PN, percutaneous radiofrequency ablation (RFA), and percutaneous cryoablation for cT1 renal masses.

DESIGN, SETTING, AND PARTICIPANTS

A total of 1803 patients with primary cT1N0M0 renal masses treated between 2000 and 2011 were identified from the prospectively maintained Mayo Clinic Renal Tumor Registry.

INTERVENTION

PN compared with percutaneous ablation.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Local recurrence-free, metastases-free, and overall survival rates were estimated using the Kaplan-Meier method and compared with log-rank tests.

RESULTS AND LIMITATIONS

Of the 1424 cT1a patients, 1057 underwent PN, 180 underwent RFA, and 187 underwent cryoablation. In this cohort, local recurrence-free survival was similar among the three treatments (p=0.49), whereas metastases-free survival was significantly better after PN (p=0.005) and cryoablation (p=0.021) when compared with RFA. Of the 379 cT1b patients, 326 patients underwent PN, and 53 patients were managed with cryoablation (8 RFA patients were excluded). In this cohort, local recurrence-free survival (p=0.81) and metastases-free survival (p=0.45) were similar between PN and cryoablation. In both the cT1a and cT1b groups, PN patients were significantly younger, with lower Charlson scores and had superior overall survival (p<0.001 for all). Limitations include retrospective review and selection bias.

CONCLUSIONS

In a large cohort of sporadic cT1 renal masses, we observed that recurrence-free survival was similar for PN and percutaneous ablation patients. Metastases-free survival was superior for PN and cryoablation patients when compared with RFA for cT1a patients. Overall survival was superior after PN, likely because of selection bias. If these results were validated, an update to clinical guidelines would be warranted.

PATIENT SUMMARY

Partial nephrectomy and percutaneous ablation for small (<7-cm) and localized renal masses are associated with similar rates of local recurrence.

Incidence of hypercoagulable events after image-guided percutaneous cryoablation of renal tumors: a single-center experience

PURPOSE

To identify retrospectively hypercoagulable events that occurred over time in patients who underwent image-guided percutaneous renal cryoablation and compare the incidence with a cohort of patients who underwent surgical partial nephrectomy (PN) during the same time period.

MATERIALS AND METHODS

An electronic medical record database was queried for patients who underwent percutaneous image-guided renal mass cryoablation or PN between September 2006 and June 2012. Records were examined for thrombotic events during the year following the procedure in each group. Incidence rates, Kaplan-Meier estimates, and patient demographic variables were compared using the stratified log-rank test and t test for independent samples.

RESULTS

The study comprised 114 cryoablation cases. The cumulative incidence of thrombotic events after 1 year was 4.39%. The incidence per 100 person-years was 4.84. There were 105 PN cases. The cumulative incidence of thrombotic events after 1 year was 1.0%. The incidence per 100 person-years was 1.14. The person-time incidence rate difference for these two groups did not reach statistical significance (P = .0894).

CONCLUSIONS

The incidence of thrombotic events in patients who underwent percutaneous renal cryoablation in this study was not significantly different than a comparable cohort who underwent surgical PN during the same time period.