The radiographic evolution of radio frequency ablated renal tumors

PURPOSE: Radio frequency ablation (RFA) of renal tumors is a relatively new technology. Few groups are familiar with the posttreatment appearance of these lesions and how they differ from cryoablated renal masses. We describe the evolution of the appearance of these lesions on followup contrast enhanced (CE) computerized tomography (CT). METHODS AND MATERIALS: A total of 64 consecutive renal tumors treated with RFA from April 2000 to September 2003 for which posttreatment CE-CT was done were included in this study. CE-CT was reviewed at 6 weeks, 3 months, 6 months and every 6 months thereafter to determine the characteristic features and evolution of these lesions. RESULTS: Renal tumors were treated with CT guided percutaneous (34), laparoscopic (28) or open (2) RFA. At a median followup of 13.7 months (range 6 weeks to 29 months) 62 RFA lesions demonstrated an absence of contrast enhancement on CE-CT. Treated endophytic tumors developed a low density, nonenhancing, wedge-shaped defect with fat infiltration seen between the ablated tissue and normal parenchyma. Treated exophytic tumors retained a configuration similar to that of the original with a lack of contrast enhancement and minimal shrinkage. Percutaneous treated lesions developed a peritumor scar or halo that demarcated ablated and nonablated tissue (perirenal fat). Persistent tumor was marked by contrast enhancement within the ablation borders of the original mass in 1 case, whereas tumor recurred after initial successful ablation with an enhancing nodule in 1. CONCLUSIONS: The radiographic features and evolution of radio frequency ablated renal tumors are unique. Successfully treated tumors demonstrated no contrast enhancement, minimal shrinkage and occasional retraction from normal parenchyma by fat infiltration.     

Radio-frequency ablation of T1a renal cell carcinoma

We report the efficacy of radio-frequency ablation (RFA) for T1a renal cell carcinoma (RCC). RFA was performed under epidural or local anesthesia by ultrasound or computed tomography (CT) guidance in seven patients with Tla RCC, who were at significant operative or anesthetic risk for invasive surgery. At a median follow-up of 17.5 months, 6 (86%) of the seven patients showed no tumor enhancement in follow-up CT scans or magnetic resonance images. Temporary macroscopic hematuria was observed in one case. RFA is an effective and safe minimally invasive therapeutic option for selected patients with RCC who have reason to avoid invasive surgery under general anesthesia.     

Conservative therapy by percutaneous radiofrequency ablation of renal cell carcinomas--therapeutic experiments of four patients with seven renal tumors--

We report 7 renal cell carcinomas in 4 patients treated by percutaneous image-guided radiofrequency ablation (RFA). The mean age of the patients was 59 years (male: 2, female: 2). All 4 were imperative cases. Two patients (5 tumor) had hereditary multiple renal cell carcinomas with von Hippel-Lindau (VHL) disease. The other two patients had sporadic renal cell carcinomas. RFA was performed guided by computed tomography under conscious sedation with local anesthetics. The mean size of the treated tumors was 4.5 (1.8-8.1) cm. Impedance-regulated RF energy from a generator at 94 (45-130) watts was applied at 11 (8-14) min intervals. The average procedure time was 91 (45-165) minutes. The maximum tissue temperature reached 82 (56-91) degrees C immediately after ablation. Three of the 7 lesions (42.9 %) were locally well controlled during the mean follow-up period of 6.3 (4-9) months. The two patients with VHL disease developed visceral metastasis after There were no major complications. Minor complications encountered included flank pain, nausea, perinephritic hematoma and fever. Although percutaneous image-guided RFA showed limited success in large or central renal tumors, the therapy against small exophytic renal tumors would be well tolerable and successful.     

The role of radiologic imaging and biopsy in renal tumor ablation

Purpose  

The rate of unintentionally discovered renal masses has been increasing along with a parallel increased incidence of renal cell carcinoma both in men and women. Ablation therapy has emerged as an alternative for the treatment of these small renal tumors. Several techniques have been developed for renal tumor ablation with cryoablation (CA) and radiofrequency ablation (RFA) being among the most widely used and studied. The purpose of this article is to review the role of imaging and renal mass biopsy in renal tumor ablation with focus on CA and RFA.     

Probe ablation as salvage therapy for renal tumors in von Hippel-Lindau patients: The Cleveland Clinic experience with 3 years follow-up

BackgroundTo evaluate the efficacy and safety of probe ablative therapy as salvage treatment for renal tumor in von Hippel-Lindau (VHL) patients after previous partial nephrectomy (PN).MethodsMedical records of VHL patients undergoing probe ablative treatment for renal tumors from March 2003 to January 2010 at our institution were retrospectively analyzed.ResultsFourteen VHL patients who were submitted to salvage probe ablative therapy were included in the analysis. Twelve patients (85%) had a solitary kidney. Overall, 33 tumors were ablated by either percutaneous cryoablation (P-Cryo) (n of procedures = 13), radiofrequency ablation (RFA) (n = 14), and laparoscopic cryoablation (L-Cryo) (n = 3). Average maximal renal tumor diameter was 2.6 ± 1 cm. Average ablation time was 18.3 ± 2.1 minutes for P-Cryo, 36.7 ± 17 minutes for RFA, and 17.3 ± 4 minutes for L-Cryo. All procedures were successfully completed without transfusions and intraoperative complications. No early postoperative complications were recorded. Postoperative decline in renal function was minimal and not clinically significant. With a mean follow-up of 37.6 months (range 12–82), 4 patients had a suspicious recurrence on computed tomogaphy/magnetic resonance imaging (CT/MRI) scan and in 3 of them a re-ablation was performed. Actuarial overall and cancer-specific survivals were 92% and 100%, respectively.ConclusionsProbe ablative therapy seems to represent a suitable treatment option for VHL patients with a previous history of PN as it offers a repeatable operation, with a high technical success rate and causing minor changes in renal function.     

Radiofrequency ablation for eradication of renal tumor in a rabbit model by using a cooled-tip electrode technique

Background:Radiofrequency ablation (RFA) has emerged as a potential alternative for surgery in clinical oncology. This animal experiment was conducted to evaluate the feasibility of RFA in the treatment of renal tumor.Methods:Eighteen rabbits with renal implantation of VX2 tumors were divided into two groups. Group A (n = 12) was treated with RFA by using a cooled-tip RF system at 30 W for 80 to 180 seconds. Group B (n = 6) received a sham operation. The therapeutic efficacy was evaluated by survival rate, magnetic resonance imaging (MRI), and histology.Results:All animals in group B died within 3 months after tumor implantation. Total tumor eradication was achieved in 10 of 12 rabbits (83.3%) in group A, of which 5 rabbits survived longer than 6 months (absolute eradication) and another 5 rabbits were found free of viable tumor when killed (relative eradication). Two rabbits experienced local tumor relapse, lung metastasis, or both. Six-month survival rate of RFA-treated rabbits was significantly higher (P < .01) than that of control rabbits. The typical MRI appearances of the acute RFA lesion consisted of five characteristic concentric zones, which corresponded to central needle track (zone A), tumor coagulation (zone B), renal tissue coagulation (zone C), peripheral hemorrhage (zone D), and inflammatory layer (zone E) on histology.Conclusions:RFA may become a promising therapy for the treatment of renal tumor. MRI is a useful modality for assessment of renal tumor ablation.     

Radiofrequency ablation for the treatment of small renal masses: safety and oncologic efficacy

The successful introduction of radio frequency ablation (RFA) into various surgical fields has fueled the interest of the urological community to study its application in small renal masses (SRM). However, some controversies remain regarding its oncologic efficacy. In this paper, we review the complication rates and highlight local ablative success and long-term oncologic outcomes of recent, larger RFA series. Review of the recent literature (Medline from January 2003 through May 2011 with the terms ("radiofrequency ablation" OR "catheter ablation") AND ("renal cell carcinoma" OR "renal tumor" OR "renal mass" OR "renal cancer" OR "kidney cancer"). Twelve RFA studies including a minimum of 35 treated tumors, and representing 717 patients were identified and analyzed for local ablative success rates and complications. Reported complications were classified according to Dindo-Clavien. Another five studies representing 172 patients were identified to assess long-term oncologic outcomes. Final pathology revealed 82.3% biopsy-proven renal cell carcinomas (RCCs) in 8 of the 12 evaluable RFA studies. Local ablative success rates after a first RFA session ranged from 67% to 100%. However, accepting a 8.8% repeat ablation rate, final success rates were 89.7-100%, with 7 of 12 studies showing final ablative success in >95%. These results demonstrate RFA to achieve adequate local tumor control regardless of histology. Risk of complications was 13.2%. Of complications, 10% were minor (grade I or II), while only 3.2% were major complications (grade ≥III). Five papers were identified describing oncological outcome at a minimum follow-up of 53 months (range 53-61.2). Progression-free survival, cancer-specific survival and overall survival ranged from 79.9 to 93.8%, 98 to 100% and 58.3 to 85%, respectively. This literature review confirms that RFA can deliver durable local tumor control and excellent long-term oncological outcomes. However, in order to achieve this, a repeat ablation rate of 8.8% has to be accepted. Complication rates are low, with 10% grade I-II and only 3.2% grade >III. These observations render RFA an attractive alternative to surgery in an elderly or comorbid population.     

Radio frequency ablation of small renal tumors:: intermediate results

Purpose

With evolving radio frequency technology, the clinical application of radio frequency ablation (RFA) has been actively investigated in the treatment for small renal tumors. We present our intermediate patient outcomes after RFA.

Materials and Methods

Since January 2001, 17 patients with a total of 24 hereditary renal tumors ranging from 1.2 to 2.85 cm were treated with RFA using the 200 W Cool-tip RF System (Radionics, Burlington, Massachusetts) under laparoscopic (9) or percutaneous (8) guidance and had a minimum 1-year followup. A percutaneous approach was considered unsuitable if kidney tumors were contiguous to bowel, ureter or large vessels. Treatment eligibility criteria included an average tumor diameter of less than 3.0 cm, tumor growth during 1 year and solid appearance with contrast enhancement (HU change greater than 20) on computerized tomography (CT). Postoperative followup consisted of CT with and without intravenous contrast, and renal function assessment at regular intervals.

Results

Median patient age was 38 years (range 20 to 51). At a median followup of 385 days (range 342 to 691), median tumor or thermal lesion diameter decreased from 2.26 to 1.62 cm (p = 0.0013), and only 1 lesion (4%), which was located centrally near the hilum, exhibited contrast enhancement (HU change greater than 10) on CT at 12 months. Of the 15 renal tumors ablated laparoscopically, 13 were in direct contact with the bowel and 2 were abutting the ureter, necessitating mobilization before RFA. Laparoscopic ultrasound was used to guide radio frequency electrode placement and monitor the ablation process in these cases. Operative time and intraoperative blood loss (mean ± standard mean of error) were 243 ± 29 minutes and 67 ± 9 cc, respectively. In 1 patient whose ureter was adherent to the tumor a ureteropelvic junction obstruction developed after laparoscopic RFA, requiring open repair.

Conclusions

At the minimum 1-year followup 23 of 24 ablated tumors lacked contrast uptake on CT, meeting our radiographic criteria of successful RFA treatment. RFA treatment of small renal tumors using the Radionics system appears to result in superior treatment outcomes compared to those of earlier series with lower radio frequency power generators. A high wattage generator might attain more consistent energy deposition with subsequent cell death in the targeted tissue due to less convective heat loss.     

Radiofrequency ablation of renal tumors

Radiofrequency ablation (RFA) of renal tumors is a relatively new treatment modality in the armamentarium of urologic surgeons. One of the challenges of this technique is attaining a zone of tissue destruction sufficient enough to kill the targeted tumor. Technologic innovations have aided in this effort. The clinical experience with RFA of renal tumors suggests that small, exophytic tumors may be more readily ablated. Although there is much optimism with regard to this technology, further study is required to better define the oncologic efficacy and refine proper patient selection.     

Treatment of renal tumors with radiofrequency ablation

BACKGROUND: Radiofrequency (RF) energy has been investigated as a minimally invasive modality for ablating small renal tumors. Recent advances in the application of this technology have improved its safety and effectiveness. MATERIALS AND METHODS: We describe the technology of RF application and review the current delivery systems as applied to renal tumor ablation. We also review relevant animal studies, which have revealed the natural history of ablated renal tissue. Finally, we examine recent human trials with an emphasis on longer-term follow-up, imaging, complications, and successful ablation according to tumor location within the kidney; i.e., central v peripheral. RESULTS: Radiofrequency ablation can be performed safely in a minimally invasive fashion either percutaneously or laparoscopically. Energy delivery varies, and available systems include dry, wet, cooled-tip, and bipolar electrodes. Heat rise and subsequent charring in the tissue adjacent to the electrode is limited by temperature or impedance-based feedback systems. In animal studies, ablation results in complete cell kill, as judged by nicotinamide adenine dinucleotide diaphorase staining. Clinical trials with intermediate follow-up show excellent success rates. Tumors >3 cm and central tumors have a higher recurrence rate after RFA than smaller, more peripheral tumors. CONCLUSIONS: The current literature suggests that RFA is a promising minimally invasive method of treating small renal tumors. Nevertheless, long-term follow-up is still required, and questions remain regarding the optimal delivery system, duration of ablation, and method of surveillance.     

Pathologic characteristics of exophytic renal masses

OBJECTIVE: Pathologic grade is an important prognostic factor for renal-cell carcinoma (RCC). The objective of this study was to determine if there is any association of radiologic characteristics with pathologic grade and type of small renal tumors. PATIENTS AND METHODS: We retrospectively reviewed the records of 500 patients who underwent extirpative renal surgery. Fifty-one patients met the inclusion criteria of solitary RCC <6 cm and adequate radiologic imaging available for review. The axial images with the largest area of tumor growing into the kidney were evaluated by a single radiologist to determine the percent of tumor that was exophytic. RESULTS: Nine patients had tumors that were >67% exophytic, and 42 patients had tumors <67% exophytic. There is a statistically significant difference in the mean Fuhrman grade for these 2 groups (1.78 v 2.25, P < 0.01). The distribution of histologic subtype was as follows: 34 patients with clear cell, 15 with papillary, and one each with chromophobe and unclassified tumors. Papillary RCC comprised 78% (7 of 9) of tumors that were >67% exophytic and 15% (3 of 20) that were <33% exophytic. The relative risk of a >67% exophytic tumor being papillary v nonpapillary is 4.1. CONCLUSIONS: Exophytic renal tumors are more likely to be of lower pathologic grade and of the papillary RCC subtype when compared with endophytic renal tumors. A larger prospective study is required to confirm these findings and determine the implications. This information may be useful when small tumors are being considered for watchful waiting or ablative therapies.     

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

Introduction and objective

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

Methods

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

Results

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

Conclusion

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

     

The contemporary role of ablative treatment approaches in the management of renal cell carcinoma (RCC): focus on radiofrequency ablation (RFA), high-intensity focused ultrasound (HIFU), and cryoablation

Introduction

Currently, most of renal tumors are small, low grade, with a slow growth rate, a low metastatic potential, and with up to 30 % of these tumors being benign on the final pathology. Moreover, they are often diagnosed in elderly patients with preexisting medical comorbidities in whom the underlying medical conditions may pose a greater risk of death than the small renal mass. Concerns regarding overdiagnosis and overtreatment of patients with indolent small renal tumors have led to an increasing interest in minimally invasive, ablative as an alternative to extirpative interventions for selected patients.

Objective

To provide an overview about the state of the art in radiofrequency ablation (RFA), high-intensity focused ultrasound, and cryoablation in the clinical management of renal cell carcinoma.

Methods

A PubMed wide the literature search of was conducted.

Results

International consensus panels recommend ablative techniques in patients who are unfit for surgery, who are not considered candidates for or elect against elective surveillance, and who have small renal masses. The most often used techniques are cryoablation and RFA. These ablative techniques offer potentially curative outcomes while conferring several advantages over extirpative surgery, including improved patient procedural tolerance, faster recovery, preservation of renal function, and reduction in the risk of intraoperative and postsurgical complications. While it is likely that outcomes associated with ablative modalities will improve with further advances in technology, their application will expand to more elective indications as longer-term efficacy data become available.

Conclusion

Ablative techniques pose a valid treatment option in selected patients.     

Long-term followup of patients with renal cell carcinoma treated with radio frequency ablation with curative intent

PURPOSE: We defined the role of radio frequency ablation in the treatment of renal cell carcinoma. MATERIALS AND METHODS: A total of 16 patients with biopsy proven renal cell carcinoma were treated with radio frequency ablation in an outpatient setting and followed for a minimum of 4 years. RESULTS: Of the 16 patients 5 died before 4 years of followup of unrelated causes. All except 1 tumor was successfully treated. All patients with exophytic tumors were successfully treated. CONCLUSIONS: Radio frequency ablation of exophytic renal cell carcinomas less than 5 cm in diameter is effective in eradicating the tumor and comparable to surgical extirpation at 4 years.     

肝脏恶性肿瘤射频消融术后早期FS-T2WI消融区周围水肿环评价消融疗效的应用

目的探讨肝脏恶性肿瘤射频消融(RFA)术后早期FS-T2WI消融区周围水肿环形态用于评价RFA疗效的价值。方法收集接受RFA治疗的18例肝癌及4例肝转移瘤患者,于术后第3天行MR平扫,观察FS-T2WI中消融区周围水肿环的形态特点;随访复查MR平扫、多期增强扫描及肿瘤标志物,评价根据FS-T2WI水肿环连续性判断RFA疗效的价值。结果消融后,22例病灶FS-T2WI消融区周围均出现高信号水肿环。19例水肿环连续,其中11例厚薄均匀,8例厚薄不均匀但形态规整、边界清晰;术后随访均无异常强化,肿瘤标志物稳定,提示消融完全。3例水肿环不连续,局部可见外凸稍高信号结节,术后1个月增强MRI可见结节状动脉期强化,血清甲胎蛋白升高,提示消融区域未完全覆盖肿瘤区域,消融不完全。结论肝脏恶性肿瘤RFA后早期FS-T2WI消融区周围水肿环对评价疗效具有一定价值,尤其对于判断短期疗效意义重大。     

Radio-frequency ablation of renal cell carcinoma in patients who were at significant risk

OBJECTIVE: Although radio-frequency ablation (RFA) has been recently applied as a minimally invasive treatment option for renal cell carcinoma (RCC), indication of this modality remains a critical issue due to the lack of complete tumor destruction as well as the uncertainty of its long-term efficacy. We report the efficacy of RFA for nine carefully selected patients with RCC who had significant reason to avoid invasive surgical treatment under general anesthesia. METHODS: Radio-frequency ablation was performed under epidural or local anesthesia by ultrasound or computed tomography (CT) guidance in nine patients with biopsy proven RCC (mean diameter, 38 mm; range, 20-53 mm), who were at significant operative or anesthetic risk for invasive surgery. Follow-up enhanced CT scans or magnetic resonance images were evaluated every 3-6 months and an evaluation of metastasis was performed every 6 months. RESULTS: At a mean follow-up of 17 months, seven (78%) of the nine patients with renal tumor showed no tumor enhancement. The renal function of all patients was well preserved. All patients were able to continue undergoing their respective treatments for active diseases in other organs in parallel to the RFA treatment. No distant metastasis, urine leakage were reported and one case of temporary hematuria and one case of peri-renal hemorrhage not requiring blood transfusion were encountered. Intra-operative ultrasonography was useful in the real-time monitoring of the minimally excessive extension of ablation into the normal parenchyma. CONCLUSION: Radio-frequency ablation appears to be an effective and safe minimally invasive therapeutic option for selected patients with RCC who have reason to avoid invasive surgery under general anesthesia.     

Radiofrequency ablation for renal tumors: Our experience

Objectives:   To report our results of percutaneous radiofrequency ablation (RFA) for renal tumors and to assess predictors of therapeutic efficacy.
Methods:   Forty patients (median age 73 years) with renal tumors were treated with RFA under local or epidural anesthesia. All of them had high surgical risk or refused radical surgery. Tumors were punctured percutaneously using the Radionics Cool-tip RF System under computed tomography or ultrasonographic guidance. Median tumor diameter was 24 mm. After RFA, contrast-enhanced computed tomography or magnetic resonance imaging was performed within 1 month. Complete response (CR) was defined as no enhancement inside the tumor. Factors related to the outcome and to renal function were assessed.
Results:   Median follow up was 16 months. CR was observed in 34 cases (85.0%). A significant difference in CR rate was observed between tumors ≤30 mm and those >30 mm. Outcomes tended to be better for tumors in the mid to lower kidney, and those away from the renal hilum. Recurrence was observed in one case (2.9%), but a CR was obtained again by additional RFA. Out of a total of 77 RFA procedures, complications occurred in only three cases (3.9%), and conservative treatment was possible in all cases. Serum creatinine levels 3 months after RFA did not differ from those before RFA.
Conclusions:   Percutaneous RFA is a safe and effective treatment for small renal tumors in patients with high surgical risk or who refuse radical surgery.     

重视病理性完全消融提高肝癌射频消融疗效

射频消融(RFA)已成为早期肝癌特别是肝细胞癌(HCC)潜在的治愈性手段.HCC的病理特点是主癌灶周围存在范围不等的微静脉浸润(MVI)区和卫星灶.RFA时,对主癌灶行完全消融,即便是有0.5～1.0 cm的消融边界,获得的通常也只是影像学完全消融,残留的癌周MVI区和卫星灶会导致肿瘤复发,影响疗效;而对包括主癌灶、MVI区和卫星灶在内的所有肿瘤组织行完全消融,是病理性完全消融,可最大程度地预防肿瘤复发,这应该是RFA治疗HCC的理想目标.文章对局部治疗视角下HCC临床病理特点、RFA治疗HCC的机制以及获得病理性完全消融的策略进行了分析.

Abstract：

Radiofrequency ablation (RFA) has been widely utilized as a potential curative treatment modality for hepatocellular carcinoma (HCC) of early stage. Pathologically, HCC is characterized by the peritumoral microvascular invasion (MVI) and satellite lesion of various scope. Complete ablation of the main tumor, even with a 0.5- 1.0 cm ablative margin, is usually only imaging complete ablation with residual of MVI and satellite lesion, which will grow and affect the therapeutic results. While complete ablation of all the tumor tissue, including the main tumor, peritumoral MVI and satellite lesion, is the pathological complete ablation with no residual of viable tumor cell, which should be the main target of RFA for HCC. This paper summarizes the clinicopathological characteristics of HCC in the perspective of locoregional therapy, the mechanism of RFA to treat HCC, and the common strategies to obtain pathological complete ablaiton.     

Preoperative patient counseling for diagnostic renal biopsy and complications with renal radiofrequency ablation

Purpose

To identify preoperative factors associated with surgical complications and successful diagnostic renal biopsy in both laparoscopic and percutaneous radiofrequency ablation (RFA) of renal masses in order to help aid in preoperative patient counseling for renal RFA.

Methods

We reviewed our Institutional Review Board approved database from November 2001 to January 2011, containing 335 tumors treated with either laparoscopic (LRFA) or percutaneous RFA (CTRFA). Preoperative patient demographics, tumor characteristics, and intraoperative surgical data were collected along with biopsy results and clinicopathologic outcomes.

Results

RFA was performed on 335 renal tumors (124 LRFA, 211 CTRFA). Non-diagnostic biopsy occurred in 18 (5.5%) tumors. Of the 317 procedures performed, 121 complications occurred in 103 (30.7%) procedures. Multivariate analysis only showed CTRFA (vs LRFA) to increase the likelihood of non-diagnostic biopsy (OR 5.1, 95% CI 1.2–22, p = 0.032). Increased tumor size (p = 0.007) and synchronous ablations (p = 0.019) increased the risk for major complications, while decreased surgeon experience (p = 0.003) and tumors close to the collecting system (p = 0.005) increased the risk of any complication.

Conclusions

Preoperative recommendations can be made to patients in the future. We suggest counseling patients that when undergoing RFA, percutaneous approach increases the risk of non-diagnostic biopsy, increased tumor size increases the risk of major complications, having more than 1 tumor ablated increases the risk of a major complication, and tumors close to the collecting system may increase the risk of complications.