Cryotherapy for liver tumors: current status, perspectives, clinical results, and review of literature

Cryoablation with KCl Solution Enhances Necrosis and Apoptosis of HepG2 Liver Cancer Cells

Cryoablation has become a valuable treatment modality for the management of liver cancer. However, one of the major challenges in cryosurgery is the incomplete cryodestruction near the edge of the iceball. This issue can be addressed by optimizing cryoablation parameters and administering thermotropic drugs prior to the procedure. These drugs help enhance tumor response, thereby strengthening the destruction of the incomplete frozen zone in liver cance. In the present study, the feasibility and effectiveness of a thermophysical agent, KCl solution, were investigated to enhance the cryodestruction of HepG2 human liver cancer cells. All cryoablation parameters were simultaneously optimized in order to significantly improve the effect of cryoablation, resulting in an increase in the lethal temperature from - 25 °C to - 17 °C. Subsequently, it was found that the application of KCl solution prior to freezing significantly decreased cell viability post-thaw compared to cryoablation treatment alone. This effect was attributed to the eutectic effect of KCl solution. Importantly, it was found that the combination of KCl solution and freezing was less effective when applied to LO2 human liver normal cells. The data revealed that the ratio of mRNA levels of Bcl-2 and bax decreased significantly more in HepG2 cells than in LO2 cells when cryoablation was used with KCl solution. In conclusion, the results of this study demonstrate the effectiveness of KCl solution in promoting cryoablation and describe a novel therapeutic model for the treatment of liver cancer that may distinguish between cancer and normal cells.

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.

Image-Guided Ablation for Colorectal Liver Metastasis: Principles, Current Evidence, and the Path Forward

Simple Summary

Colorectal cancer is the fourth most common type of cancer globally. Approximately 20% of patients with colorectal cancer present with synchronous liver metastases, and up to 60% will develop metachronous metastases during the course of the disease. Although liver resection is currently considered the local treatment of choice for colorectal liver metastasis (CLM), less than one-third of patients are eligible for surgery at the time of diagnosis of CLM. Ablation is a well-established, less invasive, locoregional therapy for patients with small CLMs, which has shown favorable oncological outcomes in patients with unresectable CLMs, comparable to those in patients eligible for surgery. The increasing knowledge of factors affecting oncological outcomes has allowed selected patients with resectable small volume CLMs to be treated with thermal ablation with curative intent. The continuous technological evolutions in imaging and image guidance have contributed to this paradigm shift in CLM treatment. The importance of patient selection, patient factors, tumor factors, ablation techniques, and clinical applications is discussed in this article.

Abstract

Image-guided ablation can provide effective local tumor control in selected patients with CLM. A randomized controlled trial suggested that radiofrequency ablation combined with systemic chemotherapy resulted in a survival benefit for patients with unresectable CLM, compared to systemic chemotherapy alone. For small tumors, ablation with adequate margins can be considered as an alternative to resection. The improvement of ablation technologies can allow the treatment of tumors close to major vascular structures or bile ducts, on which the applicability of thermal ablation modalities is challenging. Several factors affect the outcomes of ablation, including but not limited to tumor size, number, location, minimal ablation margin, RAS mutation status, prior hepatectomy, and extrahepatic disease. Further understanding of the impact of tumor biology and advanced imaging guidance on overall patient outcomes might help to tailor its application, and improve outcomes of image-guided ablation.

Experimental Investigation on Thermal Conductivity and Thermal Diffusivity of Ex-Vivo Bovine Liver from Room Temperature down to -60 °C

Ex vivo animal tissues (e.g., bovine liver) as well as water-agar gel are commonly used to simulate both experimentally and numerically the response of human tissues to cryoablation treatments. Data on the low temperature thermal properties of bovine liver are difficult to find in the literature and very often are not provided for the whole temperature range of interest. This article presents the thermal conductivity and thermal diffusivity measurements performed on ex-vivo bovine liver samples using the transient plane source method. Regression coefficients are provided to determine these properties in different temperature ranges except for the phase transition during which no results were obtained, which suggests an ad hoc calorimetric analysis. A quick procedure is also suggested to determine the water mass fraction in the tissue. Moreover, an attempt to estimate the liver density in the frozen state using measurements performed solely at room temperature is also presented. The measured thermal conductivity and thermal diffusivity values are compared with data reported in literature highlighting a spread up to 40%. Moreover, it emerges that water-agar gel usually made with 2% by weight of agar does not show the same thermal properties as the bovine liver.

Erbium:YAG laser augments the penetration of cryotherapy

Cryotherapy is commonly used during dermatologic practice. Several modifications such as an "add-on" to topicals or intralesional applications have been already defined to enhance efficacy. The aim of this study is to test our hypothesis that ablative laser application before cryotherapy would increase the depth of freezing.Throughout this experiment, target points received either cryotherapy alone or a combination of erbium:yttrium-aluminum garnet (erbium:YAG) laser and cryotherapy. Freezing durations of 10 (C10), 20 (C20), and 30 seconds (C30) were investigated. Erbium:YAG laser groups received equal high energy shots with different pulse durations (100 μs versus 1500 μs) before freezing. The treatment points were arranged on the peripheral side of porcine skin specimens, and dermoscopic images revealing the iceball visible from the lateral side were immediately captured. Repeated experimental results were compared by Wilcoxon's test. The comparison of the vertical length of the iceball between the three different freezing durations of 10 seconds, 20 seconds, and 30 seconds was statistically significant (p<0.05). The vertical length of the iceball was higher in both laser groups receiving 30-second freezing (mean ± SD: 4.32±0.53, 3.9±0.38 for micro-short pulse (MSP) and extra-long pulse (XLP), respectively) when compared with 30-second freezing alone (mean ± SD:3.51±0.44) (p=0.016). The two laser settings did not reveal a difference for the penetration of 30-second freezing (p=0.122). In this study, through visual monitorization of the iceball, erbium:YAG laser is found to augment the penetration of cryotherapy. The defined combination regimen has the potential to ameliorate treatment outcomes of cryotherapy.

Liquid Nitrogen-Based Cryoablation in In Vivo Porcine Tissue: A Pilot Study

Introduction:

Liquid nitrogen-based cryoablation induces freezing evenly throughout the probe tip surface, resulting in larger ablation volumes and faster treatment times. The purpose of this preliminary investigation is to determine the efficacy of the liquid nitrogen-based Visica2 Cryoablation System (Sanarus Technologies, Pleasanton, CA) in in vivo porcine kidney, liver, and fibro-fatty tissue.

Methods:

Ablations were performed under ultrasound guidance in 4 Yorkshire pigs. The target lesion cross-section width (W) and depth (D) were 1 cm for liver (n=8), kidney (n=4), and head-neck (n=5) and 2 cm for kidney (n=4). Expected axial length (L) of the resulting lesion is approximately 4 cm. After three-day survival, the ablated tissue was harvested and histologically analysed. The mean width and depth were compared with the target diameter using a one-sample t-test.

Results:

All animals survived the procedure. For the 1 cm target, mean dimensions (L x W x D) were 3.8±1.5 x 1.7±0.3 x 1.7±0.7 for liver, 3.0±0.5 x 2.0±0.4 x 1.7±0.6 for kidney, and 3.3±0.8 x 1.8±0.4 x 1.8±0.4 for head-neck. Mean width and depth were significantly greater than desired dimension. For the 2 cm target, mean dimensions were 3.2±0.5 x 3.1±0.8 x 1.9±0.7. Mean width and depth were not significantly different to desired target.

Conclusion:

Our preliminary results show that the Visica2 liquid nitrogen-based cryoablation system can efficiently and reproducibly create ablation volumes in liver, kidney, and fibro-fatty tissue within 4 minutes and 12 minutes for 1cm and 2cm targeted diameters, respectively. Further investigation is necessary to determine the optimal freeze-thaw-freeze protocol for larger ablation volumes.

Feasibility and safety of cryoablation on the porcine ureter using a new balloon cryoprobe

Cryoablation, as a well-characterized technology, has multifarious clinical applications. But few are reported on ureteral endometriosis. Thus, we examined the feasibility and safety of cryotherapy with a novel balloon cryoprobe on ureter in a live porcine model. During the freezing and thawing cycle, temperature was recorded in different parts of the ureter in real-time. Two-minute cryoablation could induce necrosis within range in 1 cm diameter on serosa layer. The temperature respectively dropped to -136.5 °C, -96.1 °C and -17.5 °C at the cryotherapy center, 1 cm and 1.5 cm from center on serosal side. The ureters were harvested immediately, 2 weeks or 3 months after cryotherapy. No perforation, stricture, adhesions, or hydronephrosis was observed. Histopathologic representations of ureters after cryoablation indicated that full thickness necroses of ureters were seen in all samples. The results demonstrated ureteral cryoablation using a novel balloon probe was feasible, safe, and effective. These findings provided us reference before cryoablation could be applied in clinical practice in treating ureteral endometriosis.

A novel endoscopic visible full-thickness cryoablation device on stomach

Cryoablation has been used for the treatment of various sorts of solid visceral tumors, but few are reported on gastric tumor via endoscope, in terms of accurate control of ablation site, freezing depth and effective temperature. Thus, we developed a novel device, which could perform accurate cryoablation on the stomach via endoscope. This study aimed to evaluate the efficacy and safety of the device on porcine stomach. Results showed that the novel device could provide direct view of the operation space, allowing accurate and safe ablation of the stomach. Three minutes cryoablation caused a transmural, 1 cm radius gastric lesion. On serosal side, the temperature dropped to -64.2 °C, -34.1 °C, 26.1 °C at the center, 1 cm and 2 cm from center, respectively. Histopathology revealed acute ruptured cells with damaged glands in mucosa, partial disruption in muscularis propria and serosal slight exudation. Three months later, scar formed with complete recovery of gastric structure. No active bleeding or perforation of stomach, nor injury or adhesion of adjacent organs was observed. This endoscopic cryoablation device allowed safe, full-thickness cryoablation with effective temperature, which may provide an alternative treatment for gastric tumor.

Shanghai international consensus on diagnosis and comprehensive treatment of colorectal liver metastases (version 2019)

The liver is the most common anatomical site for hematogenous metastases from colorectal cancer. Therefore effective treatment of liver metastases is one of the most challenging elements in the management of colorectal cancer. However, there is rare available clinical consensus or guideline only focusing on colorectal liver metastases. After six rounds of discussion by 195 clinical experts of the Shanghai International Consensus Expert Group on Colorectal Liver Metastases (SINCE) from 29 countries or regions, the Shanghai Consensus has been finally completed, based on current research and expert experience. The consensus emphasized the principle of multidisciplinary team, provided detailed diagnosis approaches, and guided precise local and systemic treatments. This Shanghai Consensus might be of great significance to standardized diagnosis and treatment of colorectal liver metastases all over the world.

Safety and efficacy of a China-made cryoablation device in treatment of hepatocellular carcinoma smaller than 5 cm

AIM

To assess the safety and efficacy of a China-made cryoablation device in the treatment of hepatocellular carcinoma (HCC) smaller than 5 cm.

METHODS

A total of 33 patients with HCC smaller than 5 cm were treated by cryoablation using a China-made cryoablation device under the guidance of computed tomography. Operation-associated complications within and after procedures were evaluated. The efficacy of target lesions within procedures and local recurrence rate after procedures were evaluated with imaging modalities.

RESULTS

All 37 lesions of the 33 patients were successfully treated with a China-made cryablation device. Upon the finish of procedures, complete ablation was achieved in 83.78% (31/37) of lesions, and partial ablation was achieved in 16.22% (6/37). In a median follow-up period of 10.8 mo, 32 patients remained alive and 1 was lost to follow-up. The rate of local recurrence for target lesions was 30.3% (10/33), which is equal to that achieved with imported devices.

CONCLUSION

Our findings suggest that the China-made cryoablation device is safe and effective for HCC smaller than 5 cm with the capability of destroying the whole tumor lesion.

The safety and effectiveness of liver resection for breast cancer liver metastases: A systematic review

Breast cancer liver metastases have traditionally been considered incurable and any treatment given therefore palliative. Liver resections for breast cancer metastases are being performed, despite there being no robust evidence for which patients benefit. This review aims to determine the safety and effectiveness of liver resection for breast cancer metastases. A systematic literature review was performed and resulted in 33 papers being assembled for analysis. All papers were case series and data extracted was heterogeneous so a meta-analysis was not possible. Safety outcomes were mortality and morbidity (in hospital and 30-day). Effectiveness outcomes were local recurrence, re-hepatectomy, survival (months), 1-, 2-, 3-, 5- year overall survival rate (%), disease free survival (months) and 1-, 2-, 3-, 5- year disease free survival rate (%). Overall median figures were calculated using unweighted median data given in each paper. Results demonstrated that mortality was low across all studies with a median of 0% and a maximum of 5.9%. The median morbidity rate was 15%. Overall survival was a median of 35.1 months and a median 1-, 2-, 3- and 5-year survival of 84.55%, 71.4%, 52.85% and 33% respectively. Median disease free survival was 21.5 months with a 3- and 5-year median disease free survival of 36% and 18%. Whilst the results demonstrate seemingly satisfactory levels of overall survival and disease free survival, the data are of poor quality with multiple confounding variables and small study populations. Recommendations are for extensive pilot and feasibility work with the ultimate aim of conducting a large pragmatic randomised control trial to accurately determine which patients benefit from liver resection for breast cancer liver metastases.

Analysis of circulating tumor cells in colorectal cancer liver metastasis patients before and after cryosurgery

In this study, we determined the number of peripheral blood circulating tumor cells (CTCs) pre- and post-cryosurgery in patients with colorectal cancer liver metastasis as a reference for understanding the relevance of any changes to the efficacy of cryosurgery. CTC numbers and CTC-related gene expression were measured in the peripheral blood of 55 patients with colorectal liver metastasis at 1 day before and 7 and 30 d after cryoablation using magnetic activated cell sorting (MACS) and fluorescence activated cell sorting (FACS) combined with real-time quantitative PCR (RT-qPCR). The number of CTCs decreased significantly with postoperative time (P < 0.01). Delta cycle threshold values for the CTC-related genes CEA, Ep-CAM, CK18 and CK19 increased significantly after cryoablation. Furthermore, the expression of CEA, Ep-CAM, CK18 and CK19 decreased significantly with time after cryoablation (P < 0.01). RT-qPCR and FACS combined with MACS has significant diagnostic and prognostic value for evaluating the efficacy of cryosurgery in patients with advanced colorectal cancer.

The cryoablation of lung tissue using liquid nitrogen in gel and in the ex vivo pig lung

PURPOSES

To examine the efficiency of cryoablation using liquid nitrogen in lung tissue, we measured the size and temperature distribution of the frozen area (iceball) in gel and in the ex vivo pig lungs.

METHODS

Cryoprobes with diameters of 2.4 and 3.4 mm (2.4D and 3.4D, respectively) were used. Three temperature sensors were positioned at the surface of the cryoprobe and at distances of 0.5 and 1.5 cm from the cryoprobe. The ex vivo pig lungs were perfused with 37 °C saline and inflated using ventilator to simulate in vivo lung conditions.

RESULTS

In gel, the 2.4D and 3.4D probes made iceballs of 3.9 ± 0.1 and 4.8 ± 0.3 cm in diameter, respectively, and the temperature at 1.5 cm from those probes reached -32 ± 8 and -53 ± 5 °C, respectively. In the pig lung, the 2.4D and 3.4D probes made iceballs of 5.2 ± 0.1 and 5.5 ± 0.4 cm in diameter, respectively, and the temperature at 1.5 cm from these probes reached -49 ± 5 and -58 ± 3 °C, respectively.

CONCLUSION

Liquid nitrogen cryoablation using both 2.4D and 3.4D probes made iceballs that were of sufficient size, and effective temperatures were reached in both gel and the ex vivo pig lung.

The application of cryoprobe therapy in orthopedic oncology

The cryoprobe is a relatively new surgical tool offering a more selective destruction of unwanted cells. Using expanded versions of basic thermodynamic formulas of conduction and convection, mathematical models are becoming more effective at mapping out the zone of destruction that can be expected when using cryoprobes. The development of this technology will allow for better surgical planning and postoperative care to decrease patient morbidity and mortality. It is thought that this invaluable tool will become increasingly prevalent in orthopedics.

Cryoablation plus chemotherapy in colorectal cancer patients with liver metastases

Cryoablation and surgery achieve similar removal rates for some colorectal cancer (CRC) liver metastasis removal, and systemic chemotherapy is accepted as the most important approach to improving overall survival (OS) in CRC patients with liver metastases. We aimed to evaluate the potential benefit of cryoablation plus chemotherapy in CRC patients with liver metastases. We retrospectively analyze 63 patients of CRC liver metastasis. There were 32 patients in group A, who have received cryoablation plus chemotherapy, and there were 31 patients in group B, who have received chemotherapy alone. We mainly observe the 2-year survival, the quality of life (QOL), and adverse effects. Patients in group A had a higher 2-year survival rate, better OS, better QOL, and better treatment response than patients in group B. Two-year survival rates were 71.9 and 51.6%,respectively, in group A and group B. The negative conversion rates of carcinoembryonic antigen and carbohydrate antigen 19-9 (CA199) were 57.1 and 61.5%, respectively, in group A, and 22.2 and 30%, respectively, in group B. The tumor shrinkage (a tumor volume reduction of ≥ 30%) rates were 62.5 and 22.6%, respectively, in groups A and B. Performance status remained stable or improved in 16 patients (50%) in group A and eight patients (25.81%) in group B. Cryoablation in combination with chemotherapy may increase the 2-year survival rate and improve QOL in CRC patients with liver metastasis.

EASL and mRECIST responses are independent predictors of survival in hepatocellular carcinoma patients treated with cryoablation

OBJECTIVE

The aim of this study was to determine which response evaluation criteria will best help predict the treatment efficacy of cryoablation for hepatocellular carcinoma.

MATERIALS AND METHODS

We retrospectively analyzed clinical data of 64 patients with hepatocellular carcinoma treated with cryoablation. Triphasic helical computed tomography scans were analyzed on the basis of WHO, Response Evaluation Criteria In Solid Tumors 1.1 (RECIST 1.1), modified RECIST (mRECIST), and European Association for the Study of the Liver (EASL) guidelines. We assessed the concordance among response guidelines and selected the most reliable model depending upon the correlation with overall survival.

RESULTS

Both objective response rates and disease control rates were higher for mRECIST and EASL than for WHO and RECIST 1.1 for both overall responses and target responses. The κ-value of comparisons between WHO and RECIST 1.1 and mRECIST and EASL was not more than 0.20 for both overall responses and target responses. There was consistency between WHO and RECIST 1.1 [κ=0.82, 95% confidence interval (CI): 0.72-0.91 for overall responses and κ=0.87; 95% CI, 0.76-0.94 for target responses], the same as that between mRECIST and EASL (κ=0.91, 95% CI, 0.73-0.98 for overall responses and κ=0.88, 95% CI, 0.72-0.95 for target responses). There was no significant association with survival for WHO and RECIST 1.1 responses or all target responses. The Cox-regression model showed that both mRECIST and EASL were independent predictors of overall survival, with a 51% risk reduction for mRECIST and a 61% risk reduction for EASL.

CONCLUSION

The enhancement models including mRECIST and EASL guidelines should be used in preference to WHO, RECIST 1.1, or target responses to assess the efficacy of cryotherapy.

Experimental Study on Pulmonary Cryoablation in a Porcine Model of Normal Lungs

Objective of this study is to analyze the range of necrosis after using different freezing times and freeze-thaw cycles during percutaneous cryosurgery, in order to create a suggestion for optimizing the technique for lung cryoablation. Six healthy pigs were given a CT scan and histological investigation after percutaneous cryosurgery on both lungs. Three cryoprobes were inserted into both the left and right lungs of each pig, respectively. Cryoablation was performed with two cycles of an active 10-minute freezing using argon in the left lung, each freeze followed by an active 5-minute thaw using helium. In contrast to the left lung cryoablation, the right lungs underwent 3 cycles of freeze/thaw, the first and second cycles consisted of an active 5-minute freezing followed by an active 5-minute thaw, and the third cycle of 10-minute freezing and an active 5-minute thaw. The CT imaging change of an ice ball was continuously observed. The lung tissues were taken 4 hours after cryosurgery on day 3 and on day 7, respectively, for pathological observation. One pig presented acute symptoms including bradycardia and hypothermia 30 minutes after cryosurgery, and died 4 hours after the freezing, and the other 5 pigs experienced a weak condition for 4–6 hours and then exhibited relatively normal behavior and regularly took food. The freezing area (ice ball) on CT imaging during the cryoablation grew gradually in relation to the increase over time, and along with the increase in the number of cycles. The size of the cryolesion on the lung samples became larger than the ice ball during cryosurgery, regardless of whether 2 or 3 freeze-thaw cycles were performed. The area of necrosis histologically gradually increased for the time being. Percutaneous cryosurgery on the lung can achieve complete ablation of targeted tissue. Three freeze-thaw cycles are recommended, and the range of cryoablation may not be mandatory “1 cm safe border” during cryosurgery in order to avoid harming the organ and tissue which is close to the cancer. Correct use of the technique is especially important to treat the lung neoplasms, especially the malignant tumors, which are close to the heart and large vessels.

Minimally invasive evaluation and treatment of colorectal liver metastases

Minimally invasive techniques used in the evaluation and treatment of colorectal liver metastases (CRLMs) include ultrasonography (US), computed tomography, magnetic resonance imaging, percutaneous and operative ablation therapy, standard laparoscopic techniques, robotic techniques, and experimental techniques of natural orifice endoscopic surgery. Laparoscopic techniques range from simple staging laparoscopy with or without laparoscopic intraoperative US, through intermediate techniques including simple liver resections (LRs), to advanced techniques such as major hepatectomies. Hereins, we review minimally invasive evaluation and treatment of CRLM, focusing on a comparison of open LR (OLR) and minimally invasive LR (MILR). Although there are no randomized trials comparing OLR and MILR, nonrandomized data suggest that MILR compares favorably with OLR regarding morbidity, mortality, LOS, and cost, although significant selection bias exists. The future of MILR will likely include expanding criteria for resectability of CRLM and should include both a patient registry and a formalized process for surgeon training and credentialing.

[Interventional procedures for hepatic metastases]

The therapeutic concept for hepatic metastases is mainly based on surgical resection and systemic chemotherapy. Considering technical respectability, oncological significance and limiting comorbidities, only 10-30% of patients with hepatic metastases can undergo surgery with a curative intention. Patients assessed as being non-resectable qualify in general for (palliative) chemotherapy. However, for many patients surgical therapy of the liver is no longer possible due to medical or technical reasons, nevertheless, the total tumor load is still limited, which makes an interventional, local ablative therapy approach promising, with and without chemotherapy. Thus, various interventional-radiological, minimally invasive techniques could be successfully established as oncological therapy components besides surgery and chemotherapy. These types of intervention encompass mainly chemotherapy (percutaneous alcohol instillation, transarterial chemoembolization and transarterial chemotherapy), thermotherapy (radiofrequency, laser and microwave ablations) and radio-ablative procedures (radio-embolization, selective internal radiation therapy SIRT, interstitial and catheter-guided brachytherapy). Incorporating these procedures into therapeutic multimodal concepts inaugurates a significantly broadened therapy spectrum with a clear additional improvement in patient prognosis.

Cryo-immunology: a review of the literature and proposed mechanisms for stimulatory versus suppressive immune responses

The use of cryosurgery to ablate tumors is expanding, primarily due to its technical ease and minimal morbidity. A potential secondary advantage to the in situ freezing of malignant disease is the cryo-immunologic response, the generation of an anti-tumor immune response triggered by the natural absorption of the malignant tissue. While initially proposed based on clinical observations of distant disease regressing after cryoablation of a primary tumor, results from preclinical studies have been mixed and the existence of a cryo-immunologic response has been controversial. Recent studies have shed light on the potential mechanism by which cryoablation may modulate the immune system, also reveals that both immunostimulatory and immunosuppressive responses may be triggered. This article reviews the existing evidence regarding tumor cryo-immunology and puts forward hypotheses regarding patient, tumor and technical factors that may influence the resultant immune response and warrant further investigation.

Inoperable colorectal liver metastases: a declining entity?

BACKGROUND

Untreated colorectal liver metastases (CLMs) have a dismal prognosis. Surgery remains the gold standard of treatment, but many patients will have inoperable disease at presentation. Until recently, the outlook for such patients was bleak. The purpose of this review was to report on available options in the treatment CLMs, which would be considered unresectable by conventional evaluation.

METHODS

Inclusion criteria were articles published in English-language journals reporting on either retrospective or prospective cohorts of patients undergoing treatment for conventionally inoperable CLM. Main outcome measures were survival, resectability rates, morbidity and mortality following treatment of the patients' disease.

RESULTS

Improved chemotherapy regimes and other innovative treatments have opened up new options for such patients and may even render conventionally inoperable disease resectable. The aim of treatment should be down-staging of metastases to achieve resectability, however, other treatments such as ablation may be also be used (either alone or in conjunction with resection).

CONCLUSION

A nihilistic attitude to the patient with seemingly inoperable liver metastases should be discouraged. Discussion of such patients at multi-disciplinary meetings is essential in order to plan and monitor treatments.

Hepatic yttrium-90 radioembolization of chemotherapy-refractory colorectal cancer liver metastases

PURPOSE

To present data for radioembolization with yttrium-90 ((90)Y) resin microspheres in patients with colorectal cancer liver metastases in whom currently available therapies had failed.

MATERIALS AND METHODS

Retrospective review was conducted of case files of patients with colorectal cancer liver metastases in whom chemotherapy had failed, prompting hepatic (90)Y radioembolization administered as a single-session, whole-liver treatment. Imaging and laboratory follow-up results were available for 36 patients. Response and toxicity were assessed by computed tomography/magnetic resonance imaging with the Response Evaluation Criteria in Solid Tumors and the National Cancer Institute's Common Terminology Criteria for Adverse Events, version 3.0.

RESULTS

Forty-one patients (mean age, 61 years; 30 men) received hepatic (90)Y radioembolization with resin microspheres (mean activity, 1.9 GBq). At a median interval of 2.9 months after radioembolization, partial response, stable disease, and progressive disease were demonstrated in seven, 25, and four patients, respectively. Median overall survival was 10.5 months, with improved survival for patients with a decrease in carcinoembryonic antigen level (19.1 months vs 5.4 months) and imaging response (29.3 months vs 4.3 months; P = .0001). Except for one instance of treatment-associated cholecystitis (grade 4 toxicity) and two gastric ulcers (grade 2 toxicity), no severe toxicities were observed.

CONCLUSIONS

Hepatic (90)Y radioembolization can be performed with manageable toxicity in patients with colorectal cancer liver metastases whose disease is refractory to chemotherapy. The antitumoral effect is supported by imaging and tumor marker responses. Further investigation is warranted to determine the optimal use of this emerging therapeutic modality.

Percutaneous cryoablation of small hepatocellular carcinoma with US guidance and CT monitoring: initial experience

The purpose of this study was to retrospectively determine the safety and effectiveness of percutaneous cryoablation, monitored with computed tomography (CT) and ultrasonographic (US) guidance, for the treatment of hepatocellular carcinoma (HCC). Four patients with small HCCs underwent one percutaneous cryoablation treatment session monitored with CT and US guidance. All patients underwent pretreatment blood chemistry testing and imaging evaluation. We treated lesions with simultaneous insertion of multiple 17-G cryoprobes (two or three) and defined technical success when the extension of a visible iceball was beyond 5 mm from the tumor margin. Intralesional enhancement or tumoral size increase was defined as local progression compared with that on images obtained immediately after ablation. We evaluated complications and follow-up (at 1, 3, and 6 months). All patients survived without short- or long-term complications. Cryoablation was technically successful in all patients at the end of the procedure. During follow-up two patients developed disease recurrence. One patient developed local tumor progression on the margin of the lesion; the other, a new HCC. In the case of local tumor progression a new elevation of alpha-fetoprotein (alphaFP) levels occurred at first follow-up control. In the other case levels of alphaFP remained stable during the first 3 months after the procedure, then demonstrated a progressive increase in alphaFP levels beginning at the fourth month, without tumor evidence during CT control at 3 months. We conclude that percutaneous cryotherapy with US guidance and CT monitoring is a feasible, safe, and effective for treatment of HCC. If local ablative procedures of hepatic lesions are to be performed, percutaneous cryoablation, not laparotomic, should be discussed as an alternative therapeutic measure. Longer follow-up should provide proof of the effectiveness of this technique.

Thermal maps around two adjacent cryoprobes creating overlapping ablations in porcine liver, lung, and kidney

PURPOSE

To determine cryoprobe spacing requirements in order to achieve overlapping ablation zones using the same ablation protocol in porcine liver, lung, and kidney.

MATERIALS AND METHODS

Six female pigs underwent cryoablation of the liver, lung, and kidney. Two 2.4-mm cryoprobes were spaced 20-mm apart with seven 16-gauge thermometers placed linearly and in axis with the cryoprobes at 5-mm increments from one another. The placement of the thermometers was such that three were placed between the two probes and two were placed laterally to each probe. Simultaneous use of the cryoprobes, using 12- and 8-minute double-freeze cycles, was performed with intratissue temperature monitoring during the procedure.

RESULTS

The center temperatures between the two cryoprobes in kidney, lung, and liver were -25.87( degrees )C +/- 1.91, -6.47(degrees )C +/- 3.94, and 0.48( degrees )C +/- 6.69, respectively. Dual 2.4-mm cryoprobes in our model achieved acute pathological complete coagulative necrosis zone at the center of the ablation zone between the cryoprobes only in the kidney tissue where a mean diameter of the acute complete coagulative necrosis zone was 39.6 mm +/- 0.76 mm.

CONCLUSIONS

The critical temperature of -20 degrees C was not reached at the midpoint between the probes with the 20-mm spacing arrangement in the lung and liver. These results emphasize the need for individualized organ ablation treatment protocols.

Imiquimod enhances the systemic immunity attained by local cryosurgery destruction of melanoma lesions

Melanoma lesions can be frozen in vivo, resulting in necrotic death of malignant cells and in tumor antigen release suitable for cross-presentation by professional antigen-presenting cells. Imiquimod is a small molecule with adjuvant pro-inflammatory effects that can be topically delivered as a cream. Local cryosurgery of B16/ovalbumin (OVA)-derived subcutaneous tumor nodules leads to curative destruction of the lesions. If imiquimod is repeatedly applied on the cryo-treated lesion, a conspicuous, leukocyte-rich inflammatory infiltrate appears during the days following treatment. Mice treated by cryosurgery plus imiquimod rejected rechallenges of B16/OVA in 90% of the cases, whereas cryosurgery alone failed to prevent tumor grafting in 70% of the cases. The combination treatment of B16/OVA tumors was also able to protect 60% of the mice against outgrowth of a lethal dose of non-transfected B16 tumor cells. Addition of imiquimod to cryosurgery results in increases of the cellular immune response against tumor antigens as measured by in vitro IFN-gamma production and T-cell proliferation in response to OVA. The potent memory response is not only directed against the OVA epitope, but also toward a broader range of B16 antigens. Our data indicate that these combined treatments turn the treated tumor lesion into an autologous tumor vaccine, which is even able to cause vitiligo in several cases. These preclinical data and the simplicity of the procedures warrant the design of a pilot clinical trial.

Cryoablation of liver tumours -- a review of mechanisms, techniques and clinical outcome

Several techniques exist for in situ destruction or ablation of liver tumours not eligible for resection. Cryoablation, i.e. the use of low temperatures to induce local tissue necrosis, was among the first of the thermal ablative techniques widely used. The procedures have typically been performed by surgeons during laparotomy, but recently minimally invasive cryoablation has been reported feasible. The present review focuses on mechanisms of tissue destruction, techniques of ablation including procedural monitoring, and clinical outcome following cryoablation of liver tumours. Plausible causes of tumour persistence at the site of ablation, i.e. local treatment failure, are discussed. Shortcomings exist in monitoring of the freezing process and may be a main cause. The evidence for the long-term outcome following liver tumour cryoablation needs to be improved. Cryoablation has been challenged by other techniques of tumour ablation such as radiofrequency ablation. Randomised trials against these modern techniques may define the role of cryoablation in the treatment of liver tumours. With improved imaging technology and patient selection, cryoablation of liver tumours may hold promise for selected patients.

Percutaneous cryoablation of small pulmonary malignant tumors under computed tomographic guidance with local anesthesia for nonsurgical candidates

OBJECTIVE

Cryoablation of pulmonary metastases might be a useful therapy for nonsurgical candidates.

METHODS

The procedure was performed after achievement of local anesthesia for 35 tumors in 20 patients (12 male and 8 female patients; mean age, 57 years). The primary end point was the safety and feasibility of cryoablation, and the secondary end point was tumor control assessed by follow-up dynamic computed tomographic scanning performed every 3 months.

RESULTS

Of the 22 sessions of cryoablation, pneumothorax occurred in 11, hemoptysis occurred in 8, and there was 1 case of phrenic nerve palsy. The mean hospital stay was 2.6 days. There was local recurrence of 7 (20%) tumors in 7 (35%) patients during a 9- to 28-month (median, 21 months) follow-up period. One-year survival according to the Kaplan-Meier method was 89.4%.

CONCLUSION

Percutaneous cryoablation therapy for metastatic lung tumors is feasible and minimally invasive, with satisfactory local control.