Clinical experience with open renal cryoablation

Long-term outcomes of cryoablation for biopsy-proven T1 stage renal cell carcinoma

Background

To summarize our clinical experience of cryoablation in renal cell carcinoma (RCC) of Chinese population and to evaluate the long-term outcomes of laparoendoscopic single-site (LESS) cryoablation (LCA) as well as percutaneous CT-guided cryoablation (PCA) for biopsy-proven T1a and T1b RCC.

Methods

This was a multi-center, retrospective study investigating T1 stage RCC patients from 2011 to 2021. The patients were treated by LCA or PCA according to individual situation. Overall survival (OS), cancer-related survival (CSS), and progression-free survival (PFS) were evaluated for oncological outcomes, and kidney function, complications, and hospital stay were used to estimate technical outcomes.

Results

A total of 163 consecutive patients were included. Among them, 59 cases were treated by LCA and PCA was performed in 104 cases. All operations were processed successfully. Mean diameter of the mass was (2.9±1.4) cm; median blood volume was 45ml (10~200 ml). The mean operation time was 84.0 ± 24.5 min. The median postoperative hospital stay was 3 days (1~6 days). Compared with LCA, procedure time of PCA was shortened, the volume of bleeding was reduced, and the hospital stay was decreased. The overall adverse events rate was 9.8% (16/163). The mean preoperative and postoperative eGFR of LCA were 77.6±15.3 ml/min and 75.6±17.4 ml/min, respectively. Analogously, the values of PCA were 78.7±12.9 ml/min and 76.7±14.3 ml/min. Mean follow-up time was 64.2 ± 30.2 months (range, 7–127 months). Local recurrence was observed in 13 patients (8.0%), 4 (6.8%) cases of LCA and 9 (8.7%) cases of PCA. PFS at 5 and 10 years were 95.5% and 69.2% for LCA and 96.7% and 62.8% for PCA. In total, 26 patients (16.0%) (11 patients from LCA and 15 from PCA) died throughout the follow-up period. OS at 5 and 10 years were 93.8% and 31.4% for LCA, and 97.4% and 52.7% for PCA. Six patients (3.7%) (3 cases from LCA and 3 from PCA) died of metastatic RCC. CCS for LCA were 98.0% and 82.8% at 5 and 10 years, while the data were 100% and 86.4% for PCA.

Conclusion

LCA and PCA for T1 stage RCC provides satisfactory long-term oncological and renal function preservation outcomes, with acceptable complication rates.

Ischemia Techniques in Nephron-sparing Surgery: A Systematic Review and Meta-Analysis of Surgical, Oncological, and Functional Outcomes

CONTEXT

The optimal ischemia technique at partial nephrectomy (PN) for renal masses is yet to be determined.

OBJECTIVE

To summarize and analyze the current evidence about surgical, oncological, and functional outcomes after different ischemia techniques (cold, warm, and zero ischemia) at PN.

EVIDENCE ACQUISITION

A computerized systematic literature search was performed by using PubMed (MEDLINE) and Science Direct. Identification and selection of the studies were conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) criteria. Outcomes of interest were estimated blood loss (EBL), overall complications, positive surgical margins, local tumor recurrence, and renal function preservation. Meta-analysis and forest-plot diagrams were performed. Overall pooled estimates, together with 95% confidence intervals (CIs), of the incidence of all parameters were obtained using a random effect model (RE-Model) on the log transformed means (MLN), proportion, or standardized mean change, as deemed appropriate.

EVIDENCE SYNTHESIS

One hundred and fifty-six studies were included. No clinically meaningful differences were found in terms of EBL after cold (mean: 215.5; 95% CI: 154.2-276.8m), warm (mean: 201.8; 95% CI: 175.0-228.7ml), or zero (mean: 261.2; 95% CI: 171.0-351.3ml) ischemia technique. Overall, postoperative complications were recorded in 14.1% (95% CI: 6.7-27.4), 11.1% (95% CI: 10.0-12.3), and 9.7% (95% CI: 7.7-12.2) of patients after cold, warm, and zero ischemia (p<0.01), respectively. Positive surgical margins were recorded in 4.8% (95% CI: 1.9-10.9), 4.0% (95% CI: 3.4-4.8), and 5.6% (95% CI: 3.1-9.8) of patients after cold, warm, and zero ischemia (p<0.01), respectively. Local recurrence was recorded in 3.2% (95% CI: 1.9-5.2) and 3.1% (95% CI: 0.7-11.5) of patients after warm and zero ischemia (p<0.01), respectively. The log₂ of estimated glomerular filtration ratio mean changes were-1.37 (95% CI:-3.42 to 0.68),-1.00 (-2.04 to 0.03), and-0.71 (-1.15 to-0.27) ml/min after cold, warm, and zero ischemia, respectively. Low level of evidence, retrospective nature of most of included studies, a high risk of selection bias, and heterogeneity within included studies limited the overall quality of the analysis.

CONCLUSIONS

The effect of ischemia technique at PN is still debatable and subject to confounding by several factors, namely, patients' selection criteria, surgical technique used, and percentage of functional parenchyma spared during surgery. These confounders bias available evidence and were addressed by only a small part of available studies. Unfortunately, the overall quality of literature evidences and the high risk of selection bias limit the possibility of any causal interpretation about the relationship between the ischemia technique used and surgical, oncological, or functional outcomes. Thus, none of the available ischemia technique could be recommended over the other.

PATIENT SUMMARY

The present analysis shows that none of the available ischemia techniques, namely, cold, warm, or zero ischemia, is universally superior to the others, and other factors play a role in the surgical outcome.

Distinct non-invasive evaluation values of tumor-derived cell-free microRNAs, circulating microvesicles and exosomal microRNAs after renal carcinoma cryoablation

The detection of peripheral circulating tumor-derived components, such as cell-free microRNAs, circulating microvesicles, and exosomal microRNAs, has been shown as a promising noninvasive strategy. However, the different roles of these components in tumor therapy evaluations have remained largely undefined. In this paper, we employed an in vivo model of the human clear cell renal cell carcinoma line Caki-1-bearing mice to evaluate the therapeutic effects of cryoablation, which is a new minimally invasive treatment for renal cell carcinoma. At different times after cryoablation, we found that the levels of the cell-free microRNAs miR-122, miR-155 and miR-210 were first increased and then decreased. Additionally, the number of large-sized microvesicles was increased after cryoablation, but the number of small-sized circulating microvesicles did not change. Furthermore, the exosomal microRNAs miR-126-3p, miR-17-5p, and miR-21-3p rapidly decreased one day after cryoablation, an effect that was well correlated with the treatment degree. Therefore, we suggest that these circulating components may have different levels of importance in the evaluation of the efficacy of renal cell cryoablation, furthermore, exosomal microRNAs may be more suitable for the early postoperative judgment of tumor elimination effects, which are worth further exploration in clinical practice.

Tumor cryoablation in combination with natural killer cells therapy and Herceptin in patients with HER2-overexpressing recurrent breast cancer

In this study, we investigated the clinical benefits of a combination of tumor cryoablation with natural killer (NK) cells therapy and Herceptin for human epidermal growth factor (HER) 2-overexpressing recurrent breast cancer. From May 2015 to May 2016, 48 patients who met the enrollment criteria were assigned to three groups (n=16): cryoablation group (group I), cryoablation-NK cells therapy group (group II) and cryoablation-NK cells therapy-Herceptin group (group III). Safety and short-term effects were evaluated. All the adverse effects were manageable and acceptable. The three-therapy combination treatment not only yielded good clinical efficacy, it also improved the quality of life; reduced levels of circulating tumor cells (CTCs); reduced carcino-embryonic antigen (CEA) and cancer antigen 15-3 (CA15-3) expression; enhanced immune function significantly. Furthermore, it can resulte in significant prolongation of progression free survival (PFS). This is the first clinical study to demonstrate the benefit of the three-therapy combination of tumor cryoablation, NK cells therapy, and Herceptin for HER2-overexpressing recurrent breast cancer.

Arterial Clamping Increases Central Renal Cryoablation Efficacy: An Animal Study

INTRODUCTION

The minimally invasive treatment of small renal masses with cryoablation has become increasingly widespread during the past 15 years. Studies with long-term follow-up are beginning to emerge, showing good oncological control, however, tumors with a central and endophytic location seem to possess an increased risk of treatment failure. Such tumors are likely to be subjected to a high volume of blood giving thermal protection to the cancerous cells. Arterial clamping during freezing might reduce this effect but at the same time subject the kidney to ischemia. The aim of this study was to evaluate the effect of renal artery clamping during cryoablation in a porcine survival model.

METHODS

Ten Danish Landrace pigs (approximately 40 kg) underwent bilateral laparoscopic cryoablation with clamping of the right renal artery during freezing. The cryoablation consisted of a standard double-freeze cycle of 10-minute freeze followed by 8 minutes of thaw. Arterial clamping subjected the right kidney to 2 cycles of ischemia (10 minutes) with perfusion in between. After surgery, the animals were housed for 14 days prior to computed tomography perfusions scans, radioisotope renography, and bilateral nephrectomy.

RESULTS

No perioperative or postoperative complications were experienced. Mean differential renal function was 44% (95% confidence interval: 42-46) in the clamped right kidney group and 56% (95% confidence interval: 54-58) in the nonclamped left kidney group, P < .05. The ±5% technical inaccuracy is not accounted for in the results. Mean maximum temperature between freeze cycles was 5.13°C (95% confidence interval: -0.1 to 10.3) in the clamped right kidney group and 22.7°C (95% confidence interval: -16.6 to 28.8) in the nonclamped left kidney group, P < .05. Mean cryolesion volume, estimated on computed tomography perfusion, was 12.4 mL (95% confidence interval: 10.35-14.4) in the clamped right kidney group and 6.85 mL (95% confidence interval: 5.57-8.14) in the nonclamped left kidney group, P < .05. Pathological examination shows a higher degree of vital cells in the intermediate zone of the cryolesions in the nonclamped left kidneys when compared with the clamped right kidneys.

CONCLUSION

Arterial clamping increases cryolesion size by approximately 80%, and pathologic examinations suggest a decreased risk of vital cells in the intermediate zone. The clamped kidneys showed no sign of injury from the limited ischemic insult. This study was limited by being a nontumor model.

Cryosurgery for Tumors — A Clinical Overview

Cryosurgery, a method of treating disease by the production of freezing temperatures in the tissue, is a useful technique for the treatment of tumors. When the modern era of cryosurgery began in the mid 1960's, the technique was used only for tumors easily accessible by direct observation or via endoscopy, such as those of the skin, oral cavity, and prostate gland. In general, the technique had limited usefulness in the next two decades. However, with the advent of intraoperative ultrasound as a method of monitoring the process of freezing and with the development of more effective cryosurgical apparatus, the cryosurgical treatment of tumors of the viscera and other deep tissues became practical in the 1990's. This review assesses the present day status of cryosurgery in the management of diverse tumors.

Computed tomography imaging-guided percutaneous argon-helium cryoablation of muscle-invasive bladder cancer: initial experience in 32 patients

PURPOSE

To evaluate the initial clinical experience of computed tomography (CT) imaging-guided percutaneous cryotherapy of bladder cancer.

PATIENTS AND METHODS

This study was approved by the human subjects committee. Written informed consent was obtained from all patients. Thirty-two patients (22 males and 10 females; mean age, 62.7 years) with muscle-invasive bladder cancer were treated with CT imaging-guided percutaneous cryoablation. By using CT imaging system and local anesthesia in patients, a single or multiple 1.47 mm cryoprobes were used to freeze the target bladder tumor (mean tumor size, 2.8 cm; range, 1.3-4.5 cm) with a dual freeze-thaw cycle. Follow-up was performed to assess the clinical and technical outcome of patients treated with cryoablation for a minimum of 6 months (mean, 33 months; range, 6-48 months). Tumors were considered completely ablated if there was no evidence to suggest tumor enhancement at follow-up CT images.

RESULTS

Bladder cryoablation was clinically and technically successful in all 32 cases, 30 of which required only one treatment session. Bladder integrity was maintained in all patients. Major complications were not observed in any patient.

CONCLUSION

Our initial experience of a minimally invasive method for ablating bladder tumors with CT imaging-guided percutaneous argon-helium cryoablation appears to be favorable, with acceptable operative and short-term clinical outcomes. The technique is safe and effective for the treatment of patients with muscle-invasive bladder cancer; however, long-term follow-up is needed.

Results of a prospective study comparing the clinical efficacy of cryoablation of renal cell cancer followed by immediate partial nephrectomy

PURPOSE

Evaluation if cryoablation of small renal tumours (RT) would facilitate the technique of laparoscopic partial nephrectomy (LPN) in a prospective study.

PATIENTS AND METHODS

In a prospective non-randomised study between April 2007 and October 2009, 16 patients with a mean age of 68 years (48-80 years) and a peripherally located RT were candidates for nephron-sparing surgery (5 open partial nephrectomy (OPN), 11 LPN). Cryoablation of RT was followed in the same session by open (K-OPN) and laparoscopic (K-LPN) partial nephrectomy. Perioperative and follow-up parameters were estimated. A matched-pair cohort of 41 patients (20 OPN, 21 LPN) who underwent standard operations due to the same indication has been selected for retrospective comparison (controls).

RESULTS

Mean age for K-OPN was 74 years (69-83) with mean blood loss 140 ml (50-200); for K-LPN: 66.6 years (48-80) with 100 ml (50-700). All procedures were completed successfully without conversions (K-LPN), transfusions or intra-operative complications. Compared to OPN/LPN, K-OPN and K-LPN were associated with a longer operative time (P < 0.05) and a comparable postoperative hospital stay. There were no early postoperative complications. Cryoablation has not affected the histopathological evaluation of tumours or resection margins. Histopathology showed cytologic changes suggesting fresh coagulative necrosis, glomerular vascular congestion and interstitial haemorrhages following cryotherapy. One patient (K-LPN) developed a pararenal abscess necessitating puncture after 7 weeks. The follow-up (9-42 months) was uneventful.

CONCLUSIONS

The current study shows that K-LPN is feasible without increasing procedure morbidity or compromising surgical and oncological outcomes. It adds no advantage to tumour excision. Pathological findings document early cryoablation effects but viable tissue.

Contrast-enhanced ultrasound (CEUS) follow-up after radiofrequency ablation or cryoablation of focal liver lesions: treated-area patterns and their changes over time

OBJECTIVES

To describe the early patterns of liver lesions successfully treated with radiofrequency ablation (RFA) or cryoablation (CA) and their changes over time.

METHODS

Twenty-two RFA-treated and 17 CA-treated patients underwent CEUS from week 1 to year 3 post-ablation. Patterns, margins and volumes of RF-induced and cryolesions were evaluated and compared over time.

RESULTS

After contrast enhancement, shortly after ablation, undefined margins with persistent enhancing small vessels penetrating >2 mm into the treated zone were significantly more frequent after CA (67 %) than RFA (22 %) (P < 0.02). During the arterial phase, a thin, enhancing marginal rim was seen during week 1 (T1) in around 28 % of RF lesions, while 75 % of cryolesions had thick enhancing rims (P < 0.02). The mean RF-induced lesion volume, maximum at T1 (44.1 ± 37.5 ml), shrank slowly over time, remaining clearly visible at 1 year (8.3 ± 7.4 ml). Cryolesions shrank faster (P = 0.009), from an average of 16.6 ± 7.1 ml at T1 to 1.7 ± 1.3 ml 1-year post-ablation.

CONCLUSION

RF-induced and cryolesions differ, particularly their margins and shrinkage rates. Knowing these differences allows avoidance of incomplete treatment or falsely diagnosed recurrence, especially after CA.

KEY POINTS

• Contrast-enhanced ultrasound (CEUS) provides new follow-up information following hepatic radiological inyervention. • CEUS provides good visualisation of vascular modifications after thermoablation. • RFA-induced lesions and cryoablated lesions differ. • Knowledge about RF and cryolesion patterns is essential for correct CEUS follow-up. • Cryolesions have thicker peripheral inflammatory reactions and shrink faster than RFA-induced lesions.

Ex vivo model for renal fracture in cryoablation

OBJECTIVE

To demonstrate the formation of fractures due to cryoablative therapy in a controlled model and validate the new model for the study of the complication of fractures during renal cryoablation.

METHODS

Endocare PERC-17 (1.7 mm) and Galil 17 ga IceRod (1.47 mm) probes were selected because of similar diameter and reported ice-ball size. The ex vivo model used here was a porcine kidney obtained at the supermarket. The kidneys were subsequently bivalved. The cryoprobes were inserted running just underneath the cut surface, entering the lateral surface of the kidney, and directed toward the medial surface of either the upper or lower pole. In this manner, we avoided the major calyces and involved the most parenchyma. Freeze-thaw-freeze cycles of various durations were performed. The probes were frozen parallel to each other at a distance of 20 mm apart.

RESULTS

Evidence of cryoablation-induced fracture included popping sounds noted during thaw and cracks that became visible during the phase of second freeze. Cracks were noted to extend from the probe through the parenchyma. In multiple probe freezes, the intervening zone between the 2 ice-balls had smoother ice and the fractures that appeared there originated at either probe. Fracture formation was only observed with the Endocare probes, with single or parallel freezes. No fractures were noted in the IceRod freezes.

CONCLUSION

The bivalved ex vivo kidney is an inexpensive, representative, and demonstrative model for study of fracture during cryoablation.

Cryoablation vs radiofrequency ablation for the treatment of renal cell carcinoma: a meta-analysis of case series studies

Study Type - Therapy (systematic review). Level of Evidence 2b What's known on the subject? and What does the study add? The oncological success of partial nephrectomy in the treatment of small renal masses is well established. However, partial nephrectomy has largely supplanted the radical approach. In the last decade, laparoscopy has been adopted as the new surgical approach for the treatment of renal cell carcinoma. Laparoscopy offers the advantage of lower analgesic use, shorter hospital stay, and quicker recovery time. More recently, ablative technologies have been investigated as an alternative to laparoscopic partial nephrectomy. These techniques can often be performed percutaneously in the radiology suite, or laparoscopically without the need for hilar clamping. However, only the cryoablation and radiofrequency ablation modalities have had widespread use with several series reporting short to intermediate results. This review shows that both cryoablation and radiofrequency ablation are promising therapies in patients with small renal tumours (<4 cm), who are considered poor candidates for more involved surgery.

OBJECTIVE

• To determine the current status of the literature regarding the clinical efficacy and complication rates of cryoablation vs radiofrequency ablation in the treatment of small renal tumours.

METHODS

• A review of the literature was conducted. There was no language restriction. Studies were obtained from the following sources: MEDLINE, EMBASE and LILACS. • Inclusion criteria were (i) case series design with more than one case reported, (ii) use of cryoablation or radiofrequency ablation, (iii) patients with renal cell carcinoma and, (iv) outcome reported as clinical efficacy. • When available, we also quantified the complication rates from each included study. • Proportional meta-analysis was performed on both outcomes with a random-effects model. The 95% confidential intervals were also calculated.

RESULTS

• Thirty-one case series (20 cryoablation, 11 radiofrequency ablation) met all inclusion criteria. • The pooled proportion of clinical efficacy was 89% in cryoablation therapy from a total of 457 cases. There was a statistically significant heterogeneity between these studies showing the inconsistency of clinical and methodological aspects. • The pooled proportion of clinical efficacy was 90% in radiofrequency ablation therapy from a total of 426 cases. There was no statistically significant heterogeneity between these studies. • There was no statistically significant difference regarding complications rate between cryoablation and radiofrequency ablation.

CONCLUSIONS

• This review shows that both ablation therapies have similar efficacy and complication rates. • There is urgency for performing clinical trials with long-term data to establish which intervention is most suitable for the treatment of small renal masses.

Current status of ablative therapies for renal tumors

The increase in detection of small (≤ 4 cm) renal cortical neoplasms has made nephron-sparing surgery the new standard of care for T1a renal lesions. Advances in minimally invasive surgery have improved the surgical approach to these lesions to include laparoscopic partial nephrectomy and renal ablative therapies. In this review, we discuss the indications, outcomes, and potential complications of the commonly used ablative modalities in urologic practice. We will expand on renal cryoablation and review the mechanism of action, surgical approaches, and evidence based medicine using this modality.

Thermostability of biological systems: fundamentals, challenges, and quantification

This review examines the fundamentals and challenges in engineering/understanding the thermostability of biological systems over a wide temperature range (from the cryogenic to hyperthermic regimen). Applications of the bio-thermostability engineering to either destroy unwanted or stabilize useful biologicals for the treatment of diseases in modern medicine are first introduced. Studies on the biological responses to cryogenic and hyperthermic temperatures for the various applications are reviewed to understand the mechanism of thermal (both cryo and hyperthermic) injury and its quantification at the molecular, cellular and tissue/organ levels. Methods for quantifying the thermophysical processes of the various applications are then summarized accounting for the effect of blood perfusion, metabolism, water transport across cell plasma membrane, and phase transition (both equilibrium and non-equilibrium such as ice formation and glass transition) of water. The review concludes with a summary of the status quo and future perspectives in engineering the thermostability of biological systems.

Minimally invasive treatment of small renal tumors: trends in renal cancer diagnosis and management

Renal cell carcinoma is a common malignancy causing significant mortality. In recent years abdominal imaging, often for alternate symptomatology, has led the trend toward the detection and confirmation of smaller renal tumors. This has permitted the greater use of localized and nephron-sparing techniques including partial nephrectomy and image-guided ablation. This article aims to review the current role of image-guided biopsy and ablation in the management of small renal tumors. The natural history of renal cell carcinoma, the role of renal biopsy, the principles and procedural considerations of thermal energy ablation, and the oncological outcomes of these minimally invasive treatments are discussed and illustrated with cases from the authors' institution. Image-guided ablation, in particular, has changed the treatment paradigm and, by virtue of its increasingly evident efficacy and low morbidity, now favors the treatment of smaller tumors in patients previously unfit for surgery.

The impact of renal tumor size on the efficacy of laparoscopic renal cryoablation

PURPOSE

We evaluated the impact of renal tumor size on the oncologic and surgical efficacy of laparoscopic renal cryosurgery (LRC) according to our intermediate-term experience in Korea.

MATERIALS AND METHODS

From June 2005 to October 2008, we enrolled 37 patients who underwent LRC for 40 renal tumors. Patients were stratified into four groups according to renal tumor size. Patients who presented with a maximum tumor diameter (MTD) of at least 1 cm but less than 2 cm were assigned to Group 1, those with an MTD equal to or greater than 2 but less than 3 cm were assigned to Group 2, those with an MTD equal to or greater than 3 but less than 4 cm were assigned to Group 3, and those with an MTD equal to or greater than 4 cm were assigned to Group 4. Oncologic and clinical outcomes in each group were compared.

RESULTS

The four groups showed no statistically significant differences in preoperative variables, including age, sex, body mass index, American Society of Anesthesiologists scores, baseline renal function and hemoglobin, and length of hospital stay. Regarding surgical aspects, however, operation time, estimated blood loss, and postoperative complications were significantly increased in patients with larger tumors. Three patients in Group 3 required postoperative transfusions, and 1 patient in Group 4 required conversion to open renal cryosurgery. During the mean follow-up period of 31.6 months, radiologic evidence of tumor recurrence was found in only 2 patients in Group 4.

CONCLUSIONS

In this series, LRC for renal tumors smaller than 3 cm was conducted safely without radiologic evidence of tumor recurrence during intermediate-term follow-up. For tumors larger than 3 cm, however, the transfusion rate increased, and for renal tumors larger than 4 cm, the tumor recurrence rate increased significantly.

Laparoscopic renal cryoablation: 8-year, single surgeon outcomes

PURPOSE

We present 5 to 11-year (median 8) oncological outcomes after laparoscopic renal cryoablation.

MATERIALS AND METHODS

Between September 1997 and October 2008 we performed renal cryoablation in 340 patients, of whom 80 treated laparoscopically by a single surgeon before October 2003 had a minimum 5-year followup. Followup involved magnetic resonance imaging on postoperative day 1, at 3, 6 and 12 months, and annually thereafter. Cryolesion biopsy was performed at 6 months. All data were prospectively accrued.

RESULTS

In the 80 patients with minimum 5-year followup mean age was 66 years, mean tumor size was 2.3 cm (range 0.9 to 5.0), median American Society of Anesthesiologists score was 3 and mean body mass index was 28 kg/m(2). Five patients had local recurrence, 2 had locoregional recurrence with metastasis and 4 had distant metastasis without locoregional recurrence. Six patients died of cancer. In the 55 patients with biopsy proven renal cell cancer at a median followup of 93 months (range 60 to 132) 5-year overall, disease specific and disease-free survival rates were 84%, 92% and 81%, and 10-year rates were 51%, 83% and 78%, respectively. On multivariate analysis previous radical nephrectomy for RCC was the only significant predictor of disease-free and disease specific survival (p = 0.023 and 0.030, respectively).

CONCLUSIONS

Laparoscopic renal cryoablation is effective oncological treatment for a renal mass in select patients. A disease specific survival rate of 92% at 5 years and 83% at 10 years is possible. Preceding radical nephrectomy for renal cell carcinoma was the only independent factor predicting disease-free and disease specific survival.

Single-antenna microwave ablation under contrast-enhanced ultrasound guidance for treatment of small renal cell carcinoma: preliminary experience

The purpose of this study was to determine the safety, effectiveness, and feasibility of microwave ablation (MWA) of small renal cell carcinomas (RCCs) in selected patients. Institutional review board and informed consent were obtained. From December 2007 to January 2009, 12 patients (8 male, 4 female) were enrolled in a treatment group, in which percutaneous MWA of small RCCs was performed under contrast-enhanced ultrasound guidance. The tumors were 1.7-2.9 cm in diameter (mean diameter, 2.0 cm).Therapeutic effects were assessed at follow-up with computed tomography. All patients were followed up for 3-14 months (mean, 6 months) to observe the therapeutic effects and complications (according to SIR classification). Assessment was carried out with CT imaging. No severe complications or unexpected side effects were observed after the MWA procedures. In all cases technical success was achieved. Clinical effectiveness was 100%; none of the patients showed recurrence on imaging. In conclusion, our preliminary results support the use of MWA for the treatment of small renal tumors. This technology can be applied in select patients who are not candidates for surgery, as an alternative to other ablative techniques.

Perfusion-CT monitoring of cryo-ablated renal cells tumors

Background

No single and thoroughly validated imaging method in monitoring of cryoablated renal cell carcinoma (RCC) is available. The purpose of our study was to determine the feasibility of dynamic contrast-enhanced perfusion CT (pCT) in evaluating the hemodynamic response of RCC.

Methods

15 patients (14 male, 1 female; age range, 43-81 years; mean age, 62 years) with cryoablated RCC via a transperitoneal approach, underwent to pCT 6-8 months after cryo-therapy. pCT was performed for 65 seconds after intravenous injection of contrast medium (80 mL, 370 mg iodine per millilitre, 4 mL/sec). Perfusion parameters (Time/Density curve; Blood flow, BF; Blood Volume, BV; Mean Transit Time, MTT; Permeability-Surface Area Product, PS) were sampled in the cryoablated tumor area and in ipsilateral renal cortex using deconvolution-based method. A tumor was considered to be not responsive to treatment by CT evidence of pathological contrast enhancement in the cryoablated area or renal mass persistence compared with the preoperative CT control. Written informed consent was obtained from all participants before the study.

Results

After cryotherapy, successfully ablated tumor (n = 13) showed decrease in BV (5,39 +/- 1,28 mL/100 g), BF (69,92 +/- 20,12 mL/100 g/min) and PS (16,66 +/- 5,67 mL/100 g/min) value and increased value of MTT (25,35 +/- 4,3 sec) compared with those of normal renal cortex (BV: 117,86 +/- 31,87 mL/100 g/min; BF: 392,39 +/- 117,32 mL/100 g/min; MTT: 18,02 +/- 3,6 sec; PS: 81,68 +/- 22,75 mL/100 g/min). In one patient, assessment of perfusion parameters was not feasible for breathing artifacts. One tumor showed poor response to treatment by the evidence of nodular contrast enhancement in the region encompassing the original lesion. Two typical enhancement patterns were obtained comparing the Time-Density curves of responsive and not responsive ablated tumors.

Conclusion

Perfusion CT seems to be a feasible and promising technique in monitoring the effects of cryoablation therapy.

[Current treatment of small renal masses]

Incidental diagnosis of renal carcinoma (RC) is increasingly common due to widespread use of radiodiagnostic techniques for other conditions. In developed countries, incidental tumor account for more than 40% of detected tumors, and 80% of solid kidney tumors less than 4 cm in size are malignant. Standard treatment for these tumors is partial nephrectomy, and their relapse rate is 1%-2% The higher increase in diagnosis of this disease has occurred in patients aged 70 to 90 years, a group where associated comorbidities are very common. In the past two decades, in parallel to development of radiographic techniques, two ablation procedures achieving tumor necrosis through cold, cryotherapy, and through heat, radiofrequency, have become established. These procedures achieve 95% short- and long-term remissions in tumors less than 4 cm in size. In addition, since these procedures may be performed percutaneously, both complications and hospital stay have decreased. As early as in 1995, Bosniak, based on observation of the growth and behavior of small RCs for longer than 8 years, advocated a watchful waiting or active surveillance attitude. This article reports cryotherapy, our radiofrequency series, and a literature review.

CONCLUSIONS

In the event of elderly patients, concomitant diseases advising against surgery, multiple renal tumors, a solitary kidney, or patients who reject surgery, ablation procedures may be safe and effective when performed by expert hands, achieving mid-term oncological results similar to partial nephrectomy. Active surveillance has also been shown to be safe in the mid-term in adequately informed patients. To improve indications, new diagnostic procedures that help us differentiate the potentially more aggressive tumors will be required. Larger series and longer follow-ups are neede to confirm current results.

Cryoablation of small renal tumors in patients with solitary kidneys: initial experience

Introduction. The purpose of this study was to evaluate the role of renal cryoablation in patients with solitary kidneys with the goals of tumor destruction and maximal renal parenchymal preservation. Methods. Eleven patients with single tumors were treated with cryoablation, of which 10 patients had solitary kidneys and 1 had a nonfunctioning contralateral kidney. All procedures were performed via an open extraperitoneal approach; ten tumors were treated with in-situ cryoablation and 1 tumor was treated with cryo-assisted partial nephrectomy. Results. Cryoablation was successfully performed without any preoperative complications. Mean patient age was 62.4 years (range 49–79), tumor location included: 6 (upper pole), 2 (mid-kidney), 3 (lower pole). The mean and median tumor size was 2.6 cm and 2.8 cm (range 1.2–4.3 cm), mean operative time 205 minutes (range 180–270 minutes), blood loss 98.5 ml (range 40–250 ml), and hospitalization 4.6 days (range 3–8 days). Creatinine values included: preoperative 1.43 mg/dL (range 1.2–1.9), postoperative 1.67 mg/dL (range 1.5–2.5), and nadir 1.57 mg/dL (range 1.3–2.1). All patients were followed postoperatively with magnetic resonance imaging for surveillance. At a median follow-up of 43 months, 9 patients had no evidence of recurrence, 1 patient has an enhancing indeterminate area, and 1 patient was lost to follow-up. Conclusion. Intermediate-term results suggest that renal cryoablation offers a feasible alternative for patients that require a maximal nephron-sparing effort with preservation of renal function and minimal risk of tumor recurrence.

Decision tree for laparoscopic partial nephrectomy versus laparoscopic renal cryoablation for small renal masses

PURPOSE

We propose an algorithm to help guide surgeons' decisions between laparoscopic partial nephrectomy (LPN) and renal laparoscopic cryoablation (LCA) based on preoperative parameters and outcomes defined in the literature.

PATIENTS AND METHODS

From July 2004 to December of 2007, we performed 51 LPNs and 22 LCAs. We formulated an algorithm between LPN and LCA based on outcomes from published series. Candidates for LPN are younger than 70 years; have few comorbidities; masses < or = 7 cm; and solitary, solid, and or cystic masses with an exophytic or mesophytic location. Candidates for LCA are 70 years old or older, with multiple comorbidities, masses < or = 3.5 cm, multiple masses, solid masses only, and include endophytic or hilar tumors. We then applied this decision tree to our series.

RESULTS

Our results for LPN are statistically similar to the published series except there was a higher positive margin rate in our series (11.8 v 3.5%). Our LCA series had older patients (71 v 65 y), larger masses (3.2 v 2.5 cm), and a higher rate of bleeding necessitating transfusion (18%). We applied the algorithm to all 73 patients in our series. It estimated that 45 patients should undergo LPN and 28 should undergo LCA. A correlation between the predicted surgery and the surgery performed was seen, but approximately one in five patients would have a change in the surgery performed.

CONCLUSIONS

This algorithm validates decisions surgeons are already making between LPN and LCA. While not a perfect model, it can be used to help simplify decisions between these two minimally invasive procedures to achieve optimal outcomes.

Increasing the number of biopsy cores before renal cryoablation increases the diagnostic yield

BACKGROUND AND PURPOSE

Renal cryoablation has been established as a primary management option for many small renal masses. Biopsy is performed intraoperatively and typically consists of one core being taken. This method was used to reduce the potential for seeding tumor and to minimize bleeding, although there have been no reports of tumor formation caused by biopsy seeding and blood loss is minimal. It is also associated with a relatively high yield of nondiagnostic cores. As such, in March 2005, we began taking three biopsy cores rather than one in an attempt to decrease our nondiagnostic rate.

MATERIALS AND METHODS

Biopsy results were retrospectively reviewed for patients who underwent renal cryoablation by two surgeons between February 2001 and July 2007. Findings were stratified according to the number of cores taken, which was either one or three. Tests for significance were performed using the chi-square test to determine if there was a difference in the nondiagnostic rates and the cancer yield rates.

RESULTS

Results of 119 biopsies were reviewed. Of those, a single core was taken from 81 (68%) lesions. Of these, 49 (60%) were malignant and 14 (17%) were nondiagnostic. The remaining 38 (32%) had three cores taken. Twenty-seven (71%) of these were malignant and two (5%) was nondiagnostic. The P values for cancer yield rates and nondiagnostic rates were 0.248 and 0.030, respectively.

CONCLUSIONS

Using a three-core biopsy strategy resulted in an 11% increase in cancer yield and a 12% reduction in nondiagnostic rate. Decreasing the nondiagnostic rate may help in counseling patients at follow-up. Continued investigation is warranted and under way.

Cryoablation or radiofrequency ablation of the small renal mass : a meta-analysis

BACKGROUND

The incidence of renal cell carcinoma is rising because of incidental detection of small renal masses (SRMs). Although surgical resection remains the standard of care, cryoablation and radiofrequency ablation (RFA) have emerged as minimally invasive treatment alternatives. The authors of this report performed a comparative meta-analysis evaluating cryoablation and RFA as primary treatment for SRMs.

METHODS

A search of the MEDLINE database was performed reviewing the world literature for clinically localized renal masses treated by cryoablation or RFA.

RESULTS

Forty-seven studies representing 1375 kidney lesions treated by cryoablation or RFA were analyzed. No differences were detected between ablation modalities with regard to mean patient age (P = .17), tumor size (P = .12), or duration of follow-up (P = .53). Pretreatment biopsy was performed more often for cryoablated lesions (82.3%) than for RFA (62.2%; P < .0001). Unknown pathology occurred at a significantly higher rate for SRMs that underwent RFA (40.4%) versus cryoablation (24.5%; P < .0001). Repeat ablation was performed more often after RFA (8.5% vs 1.3%; P < .0001), and the rates of local tumor progression were significantly higher for RFA (12.9% vs 5.2%; P < .0001) compared with cryoablation. The higher incidence of local tumor progression was found to be correlated significantly with treatment by RFA on univariate analysis (P = .001) and on multivariate regression analysis (P = .003). Metastasis was reported less frequently for cryoablation (1.0%) versus RFA (2.5%; P = .06). Cryoablation usually was performed laparoscopically (65%), whereas 94% of lesions that were treated with RFA were approached percutaneously.

CONCLUSIONS

Ablation of SRMs is a viable strategy based on short-term oncologic outcomes. Although extended oncologic efficacy remains to be established for ablation modalities, the current data suggest that cryoablation results in fewer retreatments and improved local tumor control, and it may be associated with a lower risk of metastatic progression compared with RFA.

Microwave tumors ablation: principles, clinical applications and review of preliminary experiences

Local ablative techniques have been developed to enable local control of unresectable tumors. Ablation has been performed with several modalities including ethanol ablation, laser ablation, cryoablation, and radiofrequency ablation. Microwave technology is a new thermal ablation technique for different types of tumors, providing all the benefits of radiofrequency and substantial advantages. Microwave ablation has been applied to liver, lung, kidney and more rarely to bone, pancreas and adrenal glands. Preliminary works show that microwave ablation may be a viable alternative to other ablation techniques in selected patients. However further studies are necessary to confirm short- and long-term effectiveness of the methods and to compare it with other ablative techniques, especially RF.

Cryoablation for small renal masses

Advances in imaging techniques (CT and MRI) and widespread use of imaging especially ultrasound scanning have resulted in a dramatic increase in the detection of small renal masses. While open partial nephrectomy is still the reference standard for the management of these small renal masses, its associated morbidity has encouraged clinicians to exploit the advancements in minimally invasive ablative techniques. The last decade has seen the rapid development of laparoscopic partial nephrectomy and novel ablative techniques such as, radiofrequency ablation (RFA), high-intensity focused ultrasound (HIFU), and cryoablation (CA). In particular, CA for small renal masses has gained popularity as it combines nephron-sparing surgery with a minimally invasive approach. Studies with up to 5-year followup have shown an overall and cancer-specific 5-year survival of 82% and 100%, respectively. This manuscript will focus on the principles and clinical applications of cryoablation of small renal masses, with detailed review of relevant literature.

Percutaneous renal cryoablation: current status

Over the last 13 years, renal cryoablation has emerged as a promising technique for the treatment of solid renal tumors. The improvement in imaging modalities such as ultrasound, computed tomography and MRI, as well as the introduction of thinner probes, has led to the spread of the minimally invasive percutaneous approach. We review the historical background of percutaneous renal cryoablation (PRC), present its basic principles, mention the contemporary clinical data and outcomes of this technique and suggest future directions for its wider application in renal tumors. Early results have demonstrated that it may offer an alternative for the treatment of small renal masses with the advantages of minimal complications, spared renal function, decreased overall costs and equivalent oncologic efficacy. Long-term results are required in order to apply this minimally invasive technique to a broader spectrum of patients.

Oncologic outcomes for ablative therapy of kidney cancer

Needle ablative therapies for small incidental renal masses are emerging as alternatives to traditional extirpative surgery. Reasons include their associated decreased morbidity, shorter convalescence, and the ability to avert the higher risk of extirpative surgery in an aging patient population. Cryoablation (CA) and radiofrequency ablation are the two most thoroughly studied needle ablative methods used for renal cancer. High-intensity focused ultrasound has also been studied but with limited published human experience at this time. For both radiofrequency ablation and CA, in vitro experiments, animal studies, and (increasingly) human experience have been published, allowing us to define appropriate candidates for such therapies, their oncologic outcomes, and the potential pitfalls. While long-term data is being collected, the current literature suggests that CA and radiofrequency ablation can be safely performed and can effectively eradicate small renal cancers with cancer-specific survival rates similar to those of traditional surgical options.

Microwave ablation of renal parenchymal tumors before nephrectomy: phase I study

OBJECTIVE

The purpose of this study was to determine, in renal neoplasms, the size of ablation zones induced in vivo with percutaneous microwave probes and whether skip areas remain within the ablation zones.

CONCLUSION

For a single 10-minute ablation, ablated volumes averaged 27 cm3 and 105 cm3 with a single-probe and a three-probe ablation array, respectively. There were no skip areas within the ablated zone. Microwave ablation can safely and quickly generate large ablation lesions and renal neoplasms.

Sequential changes after radiofrequency ablation and cryoablation of renal neoplasms: role of CT and MR imaging

Radiofrequency (RF) ablation and cryoablation are increasingly being used as minimally invasive treatments for renal malignancies. Accurate assessment of ablated tumors at postprocedural imaging is essential for evaluating the adequacy of treatment and guiding further management. Renal tumors treated with RF ablation or cryoablation appear as low-attenuation regions at computed tomography (CT) and, relative to renal parenchyma, are generally hypointense at T2-weighted magnetic resonance (MR) imaging and iso- to hyperintense at T1-weighted imaging. The use of intravenous contrast material is essential for the evaluation of possible residual or recurrent tumor. At follow-up CT or MR imaging, successfully treated renal tumors appear as focal masses that demonstrate no evidence of contrast enhancement and that frequently decrease in size over time, whereas residual or recurrent tumor can be detected as abnormal foci of contrast enhancement. Follow-up surveillance imaging is warranted because long-term results for renal tumor ablation are not known, and evaluation for residual, recurrent, or metachronous tumor is essential.

Intermediate-Term Results of Retroperitoneoscopy-Assisted Cryotherapy for Small Renal Tumours Using Multiple Ultrathin Cryoprobes

OBJECTIVES

To evaluate outcome after retroperitoneoscopic cryotherapy for small renal tumours.

METHODS

Fourteen patients underwent cryoablation performed with six ultrathin 1.5-mm cryoprobes. Retroperitoneoscopic access was used for any tumour location. A double freeze-thaw cycle was performed under simultaneous retroperitoneoscopic visual control and real-time ultrasound monitoring.

RESULTS

Mean tumour size was 2.8 cm (range: 2.0-4.0), mean patient age was 68 yr (range: 49-83), and six left and eight right kidneys were treated. The mean operative time was 167 min (range: 120-200); mean blood loss was 93 ml (range: 0-300). Cryosurgery was successfully performed in all 14 patients, with 13 patients undergoing assisted retroperitoneoscopy and one patient, after previous open nephropexy, undergoing an open approach. Intraoperative biopsy specimens revealed renal cell cancer (RCC) in 10 (71%) patients. The only intraoperative complication was bleeding after removal of the cryoprobes in four (29%) patients, necessitating one intracorporeal stitch in each. Two (14%) of the first four patients presented postoperatively with superficial skin frostbite, which healed with conservative treatment. During mean follow-up of 21 mo (range: 2-42), 2 (14%) patients died from unrelated disease, and 12 patients remained without evidence of local recurrence. One patient with previous contralateral nephrectomy for RCC developed retroperitoneal lymph node metastasis on that side without recurrence in the cryoablated kidney.

CONCLUSIONS

Retroperitoneoscopic cryotherapy using multiple ultrathin cryoprobes is safe and effective with encouraging oncologic results on intermediate-term follow-up. Prospective clinical trials and long-term oncologic data are needed to define its definitive role in treatment of renal tumours.