Meta-analysis of cryoablation versus radiofrequency ablation in the treatment of malignant liver tumors

OBJECTIVE

A meta-analysis was conducted to assess the efficacy and safety of cryoablation (CRA) compared with radiofrequency ablation (RFA).

METHODS

A systematic search of PubMed, EMBASE, Cochrane Library, Wanfang, CNKI, and VIP databases was conducted to identify clinical controlled studies comparing CRA versus RFA for hepatic malignancies up to July 2022. The meta-analysis was performed using RevMan 5.3.

RESULTS

A comprehensive analysis was conducted on 8 clinical controlled studies involving a total of 943 patients. There were no significant differences in the incidence of complications, complete ablation of lesions, local recurrence, and 1-year survival between the CRA and RFA groups (OR = 0.98, 95%CI: 0.61-1.55, p = 0.92; OR = 1.08, 95%CI: 0.62-1.90, p = 0.78; OR = 1.28, 95%CI: 0.49-3.36, p = 0.61; and OR = 1.14, 95%CI: 0.63-2.06, p = 0.66, respectively).

CONCLUSION

The efficacy and safety profile of CRA was comparable to that of RFA in the context of ablation therapy for hepatic malignancies. These findings suggested that CRA may be a valuable alternative to RFA in the treatment of hepatic malignancies.

Cryoablation inhibits the recurrence and progression of bladder cancer by enhancing tumour-specific immunity

BACKGROUND

Recurrence and metastasis of bladder cancer are major factors affecting patient prognosis. Endoscopic cryoablation achieved a better clinical outcome among clinical patients and could be synergistic with ICIs. Thus, this study aimed to evaluate the immunological mechanism of cryoablation for bladder cancer to reveal the therapeutic mechanism.

METHODS

We systematically reviewed the clinical prognosis of patients underwent cryoablation at Huashan Hospital in these first-in-human studies (ChiCTR-INR-17013060). Murine models were constructed to explore cryoablation-induced tumour-specific immunity, which was further confirmed by primary bladder tumour organoids and autologous lymphocytes cocultured system.

RESULTS

Cryoablation improved progression-free survival and recurrence-free survival respectively. Assessment of murine models after cryoablation confirmed microenvironment remodelling and tumour-specific T cells expansion. Enhanced antitumour effects were found after coculture of organoids with autologous lymphocytes collected from post-cryoablation. We also demonstrated cryoablation-induced tumour elimination required IFNGR expression on tumour cells. In addition, a long-lasting antitumour memory response is achieved by cryoablation and could be enhanced after combination with ICIs.

CONCLUSIONS

This study revealed endoscopic cryoablation is an efficient and safe therapy for bladder tumour treatment. The tumour-specific immune responses induced by cryoablation could reduce tumour recurrence and metastasis.

An update on locoregional percutaneous treatment technologies in colorectal cancer liver metastatic disease

INTRODUCTION

Liver-dominant metastatic colorectal cancer is noted in approximately 20%-35% of the patients. Systemic chemotherapy remains the first-line treatment for mCRC, but the prognosis is poor due to liver failure. Novel minimally invasive technologies have enabled the optimization of locoregional treatment options.

AREAS COVERED

This is a comprehensive review of novel locoregional treatment technologies, both percutaneous ablation and transcatheter arterial treatments, which can be used to decrease hepatic disease progression in patients with mCRC. Trans-arterial radioembolization is the most recently developed locoregional treatment for metastatic liver disease, and robust evidence has been accumulated over the past years.

EXPERT OPINION

Image-guided techniques, endovascular and ablative, have gained wide acceptance for the treatment of liver malignancies, in selected patients with non-resectable disease. The optimization of dosimetry and microsphere technological advancement will certainly upgrade the role of liver radioembolization segmentectomy or lobectomy in the upcoming years, due to its curative intent. Also, ablative interventions provide local curative intent, offering significant and sustained local tumor control. Standardization protocols in terms of predictability and reliability using immediate treatment assessment and ablation zone software could further ameliorate clinical outcomes.

Experimental Investigation of Cryoneedle Heating during MR-Guided Cryoablation in Ex Vivo Tissue Samples at 1.5-Tesla

PURPOSE

To investigate cryoneedle heating risks during magnetic resonance (MR)-guided cryoablation and potential strategies to mitigate these risks.

MATERIALS AND METHODS

Ex vivo experiments were performed on a 1.5-Tesla (T) MR scanner using an MR conditional cryoablation system on porcine tissue phantoms. Cryoneedles were placed inside the tissue phantom either with or without an angiocatheter. Typical cryoneedle geometric configurations (including gas supply line) encountered in clinical procedures with low to high expected heating risks were investigated. Up to 4 fiber optic temperature sensors were attached to the cryoneedle/angiocatheter to measure the MR-induced cryoneedle heating at different locations during MR with different estimated specific absorption rates (SARs). The impact of cryoneedle heating on cryoablation treatment was studied by comparing temperature changes during 10-min freeze-thaw cycles with and without MR.

RESULTS

Rapid temperature increases of >100 °C in < 2 minutes were observed during MR with a SAR of 2.1 W/kg. The temperature changes during a typical freeze-thaw cycle were also affected by cryoneedle heating when MR was used to monitor the ice-ball evolution. The observed cryoneedle heating was affected by multiple factors; including cryoneedle geometric configurations, sequence SAR, whether an angiocatheter was used, and whether the cryoneedle was connected to the rest of the cryoablation system.

CONCLUSIONS

The ex vivo experiments demonstrated that MR could induce significant cryoneedle heating risks. Furthermore, MR-induced cryoneedle heating can affect temperatures in the ice-ball evolution during the freeze-thaw cycle. Several practical strategies to reduce the cryoneedle heating have been proposed.

Breast cancer care during a pandemic: an opportune time for cryoablation?

Purpose

Cryoablation is a minimally-invasive percutaneous procedure that is capable of reducing the psychosocial burden of surgical delay while also decreasing the morbidity of breast cancer therapy. The purpose of this editorial is to discuss the potential role of cryoablation for reducing the psychosocial burden of surgical delay during the COVID-19 pandemic by expediting the management of breast cancer while also lessening demand on limited healthcare resources.

Methods

This editorial critiques current expert opinion recommendations that aim to reduce viral transmission and preserve healthcare resources during the COVID-19 pandemic by advocating delay of elective breast cancer surgery.

Results

The editorial summarizes the current state of the evidence that supports the selective use of cryoablation as a definite or stopgap measure in the management of breast cancer during the COVID-19 pandemic or when healthcare resources are limited.

Conclusions

As an office-based procedure performed under local anesthesia, cryoablation eliminates the need for operating room personnel and equipment while also reducing the psychosocial impact of delayed breast cancer surgery. By reducing the number of patient and healthcare provider interactions, cryoablation not only decreases the risk of viral transmission but also the need for personal protective devices during resource-limited times.

MRI-Guided Cryoablation of Hepatic Dome Hepatocellular Carcinomas Using 1-T Open High-Field-Strength Scanner

OBJECTIVE. The objective of our study was to prospectively evaluate the feasibility, safety, and effectiveness of 1-T open MRI-guided percutaneous cryoablation of hepatic dome hepatocellular carcinomas (HCCs). SUBJECTS AND METHODS. Thirty-seven patients with 37 hepatic dome HCCs underwent MRI-guided percutaneous cryoablations. MR fluoroscopy with a freehand technique was applied in the procedure. All lesions ranged in size from 8 to 38 mm. Patients were followed for at least 12 months after cryoablation or until death. Survival period, local tumor control, and complications were recorded. RESULTS. MRI-guided percutaneous cryoablation procedures were successfully performed on all 37 lesions. The technical success rate was 100%. The median follow-up time was 21.0 months (range, 10-26 months). Two patients with local tumor progression at the 4th and 11th month after the procedure were treated with a supplementary cryoablation. One patient died of upper gastrointestinal hemorrhage at the 10th month after cryoablation. Local tumor progression and overall survival rates were 2.7% (1/37) and 100% (37/37) at 6 months and 5.4% (2/37) and 97.3% (36/37) at 1 year, respectively. Postoperative hydrothorax that required chest tube drainage occurred in two patients; no other severe complications occurred. CONCLUSION. Cryoablation of hepatic dome HCCs with 1-T open MRI guidance is a feasible, safe, and effective therapy method.

Study of enhanced radiofrequency heating by pre-freezing tissue

In our previous animal model study, we found that radiofrequency (RF) ablation of pre-frozen tumor resulted in improved therapeutic effects. To understand the underlying mechanisms and optimize the treatment protocol, the RF heating pattern in pre-frozen tissue was studied in this paper. Both ex vivo and in vivo experiments were conducted to compare the temperature profiles of RF heating with or without pre-freezing. Results showed that the heating rate of in vivo tissues was significantly higher with pre-freezing. However, little difference was observed in the heating rate of ex vivo tissues with or without pre-freezing. In the histopathologic analysis of in vivo tissues, both a larger ablation area and a wider transitional zone were found in the tissue with pre-freezing. To investigate the cause for the enhancement in RF heating, the parameters affecting the tissue temperature rise were studied. It was found that the electrical conductivity of in vivo tissue with pre-freezing was much higher at low frequencies, but little difference was found at the 460 kHz frequency commonly used in clinical applications. A finite element model for RF heating was developed and validated to fit the thermal conductivity of in vivo tissue including effects of pre-freezing and the associated blood perfusion rate. Results showed that the enhancement of the heating rate was primarily attributed to the decreased blood perfusion rate in the tissue with vascular damage caused by pre-freezing. The ablation volume was increased by 104% due to the reduced heat dissipation.

Infectious Complications of Cryoablation and Microwave Ablation in Metastatic Solid Tumors

Cryoablation and microwave ablation are commonly used techniques to reduce tumor burden in unresectable neoplasms. This retrospective study demonstrated low risk for infectious complications (1.4%) following these invasive procedures. Abscess formation was the most common infection around the ablation sites. All infections were successfully treated with imaging-guided drainage and antibiotics.Infect Control Hosp Epidemiol 2018;39:723-726.

Use of cryoablation beyond the prostate

Cryoablation has been used for many years as a surgical ablation technique in the prostate and kidney. However, since the introduction of high-intensity focused ultrasound (HIFU) and robotic surgery for prostate tumours, its popularity in the urologic community has declined. In the early 2000s, innovations in cryoablation technology allowed the use of thinner probes, which were suitable for percutaneous application. As a result, radiologists began using cryoablation, first in the liver, and then in other organs or tissues such as the kidney, lung, breast, pancreas, bone, and soft tissue. In most of these locations, cryoablation has great potential given its inherent advantages, including the use of local anaesthesia, little or no pain during and after the procedure, real-time monitoring of the ablation area on US, CT or MRI, the potential for ablation of large tumours with multiple probes, and the ability to change the shape of the ablation in non-spherical tumours. Yet despite these advantages, the use of percutaneous cryoablation among radiologists appears to be far lower than that of heat-based ablation techniques. The aim of this article is to outline specific aspects of cryoablation and to illustrate its potential clinical applications with case presentations.

KEY POINTS

• Recent advances have made cryoablation suitable for percutaneous use by radiologists with image guidance. • Cryoablation has distinct advantages over heat-based ablation techniques. • Cryoablation is becoming increasingly popular for lung, breast, kidney, bone, and soft tissue tumours.