Percutaneous renal cryoablation: current status

Endophytic upper tract urothelial carcinoma in a solitary kidney treated by cryotherapy: an unorthodox case for successful management

BACKGROUND

Nephroureterectomy remains the gold standard treatment for upper tract urothelial carcinoma (UTUC). Considering the high risk of developing renal function impairment after surgery, the rationale for nephron sparing approaches in treatment of UTUC has been raised. In this case, renal cryoablation was able to achieve successful oncologic control while preserving renal function during 5 years of follow up without intraoperative or post operative complications.

CASE PRESENTATION

A 79 year old male presents after three months of macroscopic hematuria. Imaging revealed a 3.6 × 3.1 × 2.7 cm endophytic mass in the interpolar region of the left kidney and an atrophic right kidney. After weighing the lesion's location with the patient's of complex medical history, he was counselled to undergo a minimally invasive percutaneous cryoablation as treatment for his solitary renal mass. A diagnostic dilemma was encountered as imaging suggested a diagnosis of renal cell carcinoma. However, the pre-ablation biopsy established an alternative diagnosis, revealing UTUC. Percutaneous cryoablation became an unorthodox treatment modality for the endophytic component of his UTUC followed by retrograde ureteroscopic laser fulguration. The patient was followed in 3 months, 6 months, then annually with cross sectional imaging by MRI, cystoscopy, urine cytology and renal function testing. After five years of follow-up, the patient did not encountered recurrence of UTUC or deterioration in renal function, thereby maintaining a stable eGFR.

CONCLUSION

Although evidence for nephron-sparing modalities for UTUC is mounting in recent literature, limited data still exists on cryotherapy as a line of treatment for urothelial carcinoma. We report successful management of a low-grade UTUC using cryoablation with the crucial aid of an initial renal biopsy and long-term follow-up. Our results provide insight into the role of cryoablation as a nephron-sparing approach for UTUC.

Measurement Analysis of Ice Ball Size during CT-Guided Cryoablation Procedures for Better Prediction of Final Ice Ball Size and Avoidance of Complications

Introduction Cryoablation is the destruction of living tissue by the application of extreme freezing temperature. There has been an increase in the use of cryoablation in the management of musculoskeletal lesions, in particular fibromatosis.

Aim This study aimed to measure the average and relative increase in size of the cryoablation ice ball after the first (10 minutes) and second freeze cycles (20 minutes) to accurately predict the size of the ice ball between first and second freezes to help prevent any unwanted damage of the nearby skin and neurovascular structures. This is especially important when ablating in relatively small body parts such as in the appendicular skeleton.

Material and Methods Eight patients treated with cryoablation over a 12-month period for fibromatosis were, included in the study. The size and volume of the ice ball were measured during the first and second cycle of cryoablation.

Results The average patient age of the cohort was 35.6 years old (min 28 and max 43). There was female predominance in the study (3:2, F:M). There was a significant increase (26%) in the linear dimensions and almost doubling in the volume of the ice ball between freeze cycles (p-value = 0.0037 for dimensions and p-value = 0.0002 for volumes).

Conclusion This pilot study is a preliminary attempt to predict the eventual size of the ice ball during cryoablation procedures when treating cases of fibromatosis. This should help in planning cryoablation to ensure decrease morbidity by preventing injury to adjacent critical structures (neurovascular bundle and skin).

Percutaneous cryoablation vs. open partial nephrectomy in small kidney cancers: the Italian experience

INTRODUCTION

The aim of the present work was to analyze the economic impact of PCA (percutaneous cryoablation) vs. OPN (open partial nephrectomy), as it represents the most common standard of care for SRMs (small renal masses), namely T1a renal cancers (<4 cm), in Italy.

EVIDENCE ACQUISITION

A cost analysis was performed to compare the difference of the total perioperative costs between PCA and OPN, both from the perspective of the National Healthcare System and the hospital. Clinical and resources consumption inputs were retrieved by a non-systematic literature search on scientific databases, complemented by a grey literature research, and validated by expert opinion. Costs calculation for the NHS perspective were based on reference tariffs published by the National Ministry of Health, while for the hospital perspective, unit costs published in the grey literature were used to compare the two alternatives.

EVIDENCE SYNTHESIS

Assuming the NHS perspective, the cost analysis shows there is an economic advantage in using PCA vs. OPN (€4080 vs. €7541) for the treatment of SRMs. Hospitalization time is the driver of the total costs, while the costs of complications are quite negligible in both groups. From the hospital perspective the costs of PCA is slightly higher (+€737) than OPN, with cryoprobes contributing as the greatest cost component. However, this increase is quite restrained and is offset by an inferior use of healthcare resources (surgery room, healthcare personnel, length of stay in the hospital).

CONCLUSIONS

According to our analysis, PCA results an advantageous technique compared to OPN respectively in terms of costs and resource consumption from both the NHS and the hospital perspective.

Cancer immunotherapy using tumor cryoablation

Cryoablation is increasingly being used as a primary treatment for localized cancers and as a salvage therapy for metastatic cancers. Anecdotal clinical reports and animal experiments have confirmed an induction of systemic antitumor immune response by tumor cryoablation. To capitalize on the stimulatory effects of cryoablation for cancer immunotherapy, this response must be intensified using other immunomodulatory agents. This article reviews the preclinical and clinical evidence and discusses the mechanism of the antitumor immune response generated by cryoablation. The rationale and evidence behind several immunotherapy approaches that can be combined with cryoablation to devise a cryoimmunotherapeutic strategy with a potential to impact the progression of metastatic disease are described.

Thermochemical Ablation: A Device for a Novel Interventional Concept

Solid focal and oligometastatic malignancies are appropriate targets for minimally invasive ablative procedures. Thermochemical ablation is an experimental minimally invasive procedure, which exploits certain features of current thermal and chemical tumor ablation therapies. Engineering principles have been used to design a device, which has been research-proven-capable of coagulating tissue through the combination of a thermal and chemical insult. This interventional device completes this assignment by separately guiding the flow of chemical reagents, drawn from auxiliary systems, to a point at the distal tip of an assembled apparatus. At this position, the respective flow-streams converge and undergo an exothermic reaction to produce a heated, hyperosmolar solute, which serves to ablate the targeted tissue. Ex and in vivo studies have confirmed the utility of this device and the physiologic toleration of this interventional concept.

Radiation dose reduction for CT-guided renal tumor cryoablation

OBJECTIVE

The purpose of this article is to retrospectively determine the image quality and degree of radiation dose reduction that is clinically acceptable for CT-guided renal tumor cryoablation.

MATERIALS AND METHODS

A total of 15 patients (17 procedures; mean age, 67 years; range, 38-85 years) undergoing clinically indicated CT-guided renal tumor cryoablation procedures were included in this retrospective study. A previously validated noise-insertion tool was used to simulate reduced-dose scans at 75%, 50%, 25%, and 10% of the original dose at four representative phases of the cryoablation procedure. Images obtained at different dose levels were randomized and reviewed by three radiologists blinded to the level of dose reduction, who scored them independently with a 5-point scale (1-5, with 5 the best). Images with a mean score of 3 or higher were considered diagnostically acceptable. The minimal acceptable dose was that at which 90% of images were considered diagnostically acceptable. Interrater agreement was assessed using the weighted kappa statistic.

RESULTS

The weighted kappa value was 0.68, indicating substantial agreement among the reviewers. The averaged percentage of diagnostically acceptable images for the four series was 100% for a full dose, 98-100% for the 75% dose level, 94-98% for the 50% dose level, and less than 90% for images obtained at the 25% and 10% dose levels, which was considered unacceptable.

CONCLUSION

On the basis of results from 15 patients (17 procedures), images obtained from CT acquisitions at 50% (volume CT dose index, 12.2 mGy) of the original dose level (volume CT dose index, 24.4 mGy) were acceptable for the purpose of CT monitoring of renal cryoablation procedures.

Cryoablation: mechanism of action and devices

Cryoablation refers to all methods of destroying tissue by freezing. Cryoablation causes cellular damage, death, and necrosis of tissues by direct mechanisms, which cause cold-induced injury to cells, and indirect mechanisms, which cause changes to the cellular microenvironment and impair tissue viability. Cellular injury, both indirect and direct, can be influenced by four factors: cooling rate, target temperature, time at target temperature, and thawing rate. In this review, the authors describe the mechanisms of cellular injury that occur with cryoablation, the major advantages and disadvantages of cryoablation compared with other thermal ablation techniques, and the current commercially available cryoablation ablation systems.