Chemical ablation of liver cancer

Percutaneous liquid ablation agent for tumor treatment and drug delivery

Percutaneous locoregional therapies (LRTs), such as thermal ablation, are performed to limit the progression of hepatocellular carcinoma (HCC) and offer a bridge for patients waiting for liver transplantation. However, physiological challenges related to tumor location, size, and existence of multiple lesions as well as safety concerns related to potential thermal injury to adjacent tissues may preclude the use of thermal ablation or lead to its failure. Here, we showed a successful injection of an ionic liquid into tissue under image guidance, ablation of tumors in response to the injected ionic liquid, and persistence (28 days) of coinjected chemotherapy with the ionic liquid in the ablation zone. In a rat HCC model, the rabbit VX2 liver tumor model, and 12 human resected tumors, injection of the ionic liquid led to consistent tumor ablation. Combining the ionic liquid with the chemotherapy agent, doxorubicin, resulted in synergistic cytotoxicity when tested with cultured HCC cells and uniform drug distribution throughout the ablation zone when percutaneously injected into liver tumors in the rabbit liver tumor model. Because this ionic liquid preparation is simple to use, is efficacious, and has a low cost, we propose that this new LRT may bridge more patients to liver transplantation.

Treatment of liver cancer of middle and advanced stages using ultrasound-guided percutaneous ethanol injection combined with radiofrequency ablation: A clinical analysis

Liver cancer is a malignancy of the digestive system and has a high morbidity and mortality rate. Local intervention has become a viable option in identifying liver treatment. The aim of the present study was to analyze the clinical effects of treating liver cancer in middle and advanced stages using ultrasound-guided percutaneous ethanol injection (PEI) in tumors combined with radiofrequency ablation (RFA). A total of 100 patients with stage III-IV liver cancers were selected to participate in the study. Patients were divided into groups. In group A, treatment was initiated with PEI and after 1-2 weeks RFA was applied while in group B treatment was initiated with RFA and after 1-2 weeks PEI was applied. Patients in group C received PEI and RFA simultaneously. The clinical effects in the 3 groups were compared after 6-month follow ups. The volume of tumor ablation necrosis in group A was significantly greater than that in the groups B and C, while the size was significantly smaller compared to groups B and C after ablation. For group A, the complete ablation rate was significantly higher than that in groups B and C, and the differences were statistically significant (P<0.05). Liver damage indices, including raising levels of glutamic-pyruvic transaminase and total bilirubin, were significantly decreased in group A (P<0.05). The survival rate in group A was also significantly higher than in groups B and C (P<0.05). In conclusion, for patients with liver cancer in middle and advanced stages, the treatment method using PEI followed by RFA was more beneficial in terms of improving the tumor ablation rate, alleviating liver damages and increasing survival rates.

Extending the Frontiers Beyond Thermal Ablation by Radiofrequency Ablation: SBRT, Brachytherapy, SIRT (Radioembolization)

Metastatic spread of the primary is still defined as the systemic stage of disease in treatment guidelines for various solid tumors. This definition is the rationale for systemic therapy. Interestingly and despite the concept of systemic involvement, surgical resection as a local treatment has proven to yield long-term outcomes in a subset of patients with limited metastatic disease, supporting the concept of oligometastatic disease. Radiofrequency ablation has yielded favorable outcomes in patients with hepatocellular carcinoma and colorectal metastases, and some studies indicate its prognostic potential in combined treatments with systemic therapies. However, some significant technical limitations apply, such as size limitation, heat sink effects, and unpredictable heat distribution to adjacent risk structures. Interventional and non-invasive radiotherapeutic techniques may overcome these limitations, expanding the options for oligometastatic patients and cytoreductive concepts. Current data suggest very high local control rates even in large tumors at any given location in the human body. The article focusses on the characteristics and possibilities of stereotactic body radiation therapy, interstitial high-dose-rate brachytherapy, and Yttrium-90 radioembolization. In this article, we discuss the differences of the technical preferences as well as their impact on indications. Current data is presented and discussed with a focus on application in oligometastatic or cytoreductive concepts in different tumor biologies.

Synergistic ablation of liver tissue and liver cancer cells with high-intensity focused ultrasound and ethanol

We investigated the combined effect of ethanol and high-intensity focused ultrasound (HIFU), first, on heating and cavitation bubble activity in tissue-mimicking phantoms and porcine liver tissues and, second, on the viability of HepG2 liver cancer cells. Phantoms or porcine tissues were injected with ethanol and then subjected to HIFU at acoustic power ranging from 1.2 to 20.5 W (HIFU levels 1-7). Cavitation events and the temperature around the focal zone were measured with a passive cavitation detector and embedded type K thermocouples, respectively. HepG2 cells were subjected to 4% ethanol solution in growth medium (v/v) just before the cells were exposed to HIFU at 2.7, 8.7 or 12.0 W for 30 s. Cell viability was measured 2, 24 and 72 h post-treatment. The results indicate that ethanol and HIFU have a synergistic effect on liver cancer ablation as manifested by greater temperature rise and lesion volume in liver tissues and reduced viability of liver cancer cells. This effect is likely caused by reduction of the cavitation threshold in the presence of ethanol and the increased rate of ethanol diffusion through the cell membrane caused by HIFU-induced streaming, sonoporation and heating.

Radiofrequency ablation is superior to ethanol injection in early-stage hepatocellular carcinoma irrespective of tumor size

Background

Randomized trials suggest that radiofrequency ablation (RFA) may be more effective than percutaneous ethanol injection (PEI) in the treatment of hepatocellular carcinoma (HCC). However, the survival advantage of RFA needs confirmation in daily practice.

Methods

We conducted a population-based cohort study using the Taiwan Cancer Registry, National Health Insurance claim database and National Death Registry data from 2004 through 2009. Patients receiving PEI or RFA as first-line treatment for newly-diagnosed stage I-II HCC were enrolled.

Results

A total of 658 patients receiving RFA and 378 patients receiving PEI treatment were included for final analysis. The overall survival (OS) rates of patients in the RFA and PEI groups at 5-year were 55% and 42%, respectively (p < 0.01). Compared to patients that received PEI, those that received RFA had lower risks of overall mortality and first-line treatment failure (FTF), with adjusted hazard ratios (HRs) [95% confidence interval (CI)] of 0.60 (0.50-0.73) for OS and 0.54 (0.46-0.64) for FTF. The favorable outcomes for the RFA group were consistently significant for patients with tumors > 2 cm as well as for those with tumors < 2 cm. Consistent results were also observed in other subgroup analyses defined by gender, age, tumor stage, and co-morbidity status.

Conclusion

RFA provides better survival benefits than PEI for patients with unresectable stage I-II HCC, irrespective of tumors > 2 cm or ≤ 2 cm, in contemporary clinical practice.

Dual mode single agent thermochemical ablation by simultaneous release of heat energy and acid: hydrolysis of electrophiles

PURPOSE

This study aimed to investigate two readily available electrophilic reagents, acetyl chloride (AcCl), and acetic anhydride (Ac(2)O), for their potential in tissue ablation.

MATERIALS AND METHODS

Reagents were diluted in diglyme as solutions up to 8 mol/L and tested in a gel phantom with NaOH solutions and ex vivo in porcine liver. Temperature, pH, and volume measurements were obtained. Infrared and gross pathological images were obtained in bisected specimens immediately after injection.

RESULTS

AcCl was much more reactive than Ac(2)O and AcCl was therefore used in the tissue studies. Temperature increases of up to 37°C were noted in vitro and 30°C in ex vivo tissues using 4 mol/L AcCl solutions. Experiments at 8 mol/L were abandoned due to the extreme reactivity at this higher concentration. A change in pH of up to 4 log units was noted with 4 mol/L solutions of AcCl with slight recovery over time. Ablated volumes were consistently higher than injected volumes.

CONCLUSIONS

Reaction of electrophiles in tissues shows promise as a new thermochemical ablation technique by means of only a single reagent. Further studies in this area are warranted.

Imaging and Imaging-Guided Interventions in the Diagnosis and Management of Hepatocellular Carcinoma (HCC)-Review of Evidence

The imaging of hepatocellular carcinoma (HCC) is challenging and plays a crucial role in the diagnosis and staging of the disease. A variety of imaging modalities, such as ultrasound, computed tomography (CT), magnetic resonance imaging (MRI) and nuclear medicine are currently used in evaluating patients with HCC. Although the best option for the treatment of these cases is hepatic resection or transplantation, only 20% of HCCs are surgically treatable. In those patients who are not eligible for surgical treatment, interventional therapies such as transcatheter arterial chemoembolization (TACE), percutaneous ethanol injection (PEI), radio-frequency ablation (RFA), percutaneous microwave coagulation therapy (PMC), laser ablation or cryoablation, and acetic acid injection are indicated. In this paper, we aimed to review the evidence regarding imaging modalities and therapeutic interventions of HCC.

Spectroscopic and Calorimetric Evaluation of Chemically Induced Protein Denaturation in HuH-7 Liver Cancer Cells and Impact on Cell Survival

Solid tumors such as hepatocellular carcinoma are very often not amenable to chemotherapy and radiotherapy. Local ablation methods, including chemical ablation with absolute ethanol, are therefore an option for treatment but lack of information about the mechanism of devitalization leading to cell death is a hindrance to further adoption. Systemic toxicity also has limited the amount of ethanol that can be used in a single treatment session. Therefore we evaluated the mechanism of urea, a denaturant with little or no systemic toxicity, for potential use in chemical ablation. In this study we report on the use of three methods to analyze the effects in cell culture with a view towards eventual clinical application. Human hepatoma HuH-7 cells were analyzed at several time points after treatment using FTIR, DSC, and Raman microspectroscopy based on MTT and PI-exclusion viability assays. Time course fractional denaturation data plotted against viability show that a 50% viability drop occurs after only a 10–20% drop in overall protein denaturation. Other methods of cell death such as apoptosis may also be operative, but this result implies that protein denaturation is one of the major mechanisms of cell death. This is in line with what has been previously suggested for purely thermal methods, and opens the way to mechanism-based improvements in chemical ablation of solid tumors.

In vivo comparison of simultaneous versus sequential injection technique for thermochemical ablation in a porcine model

PURPOSE

To investigate simultaneous and sequential injection thermochemical ablation in a porcine model, and compare them to sham and acid-only ablation.

MATERIALS AND METHODS

This IACUC-approved study involved 11 pigs in an acute setting. Ultrasound was used to guide placement of a thermocouple probe and coaxial device designed for thermochemical ablation. Solutions of 10 M acetic acid and NaOH were used in the study. Four injections per pig were performed in identical order at a total rate of 4 mL/min: saline sham, simultaneous, sequential, and acid only. Volume and sphericity of zones of coagulation were measured. Fixed specimens were examined by H&E stain.

RESULTS

Average coagulation volumes were 11.2 mL (simultaneous), 19.0 mL (sequential) and 4.4 mL (acid). The highest temperature, 81.3°C, was obtained with simultaneous injection. Average temperatures were 61.1°C (simultaneous), 47.7°C (sequential) and 39.5°C (acid only). Sphericity coefficients (0.83-0.89) had no statistically significant difference among conditions.

CONCLUSIONS

Thermochemical ablation produced substantial volumes of coagulated tissues relative to the amounts of reagents injected, considerably greater than acid alone in either technique employed. The largest volumes were obtained with sequential injection, yet this came at a price in one case of cardiac arrest. Simultaneous injection yielded the highest recorded temperatures and may be tolerated as well as or better than acid injection alone. Although this pilot study did not show a clear advantage for either sequential or simultaneous methods, the results indicate that thermochemical ablation is attractive for further investigation with regard to both safety and efficacy.

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.

Ablative Technologies in the Management of Patients with Primary and Secondary Liver Cancer: An Overview

Interventional ablative technologies have played an increasingly important role in the management of patients with primary or secondary liver malignancies. Ethanol and acetic acid ablation were the primary modalities available 2 decades ago. Today, several new technologies are available, including radiofrequency ablation, cryoablation, and microwave ablation. Radiofrequency ablation is the most widely practiced, however, cryoablation and microwave ablation are reasonable choices in certain situations. Irreversible electroporation is a newer technique, which has yet to enter clinical practice, but shows promising preliminary results. Herein, we provide a brief overview of the above-mentioned technologies with a focus on principles of ablation and technique. We also describe the use of these techniques in the context of cytoreduction, a noncurative approach aimed at reducing the overall tumour burden and providing concomitant survival benefit.

Clinical outcomes of radiofrequency ablation, percutaneous alcohol and acetic acid injection for hepatocelullar carcinoma: a meta-analysis

BACKGROUND & AIMS

Radiofrequency ablation (RFA) is often the preferred local ablation therapy for hepatocellular carcinoma (HCC). Percutaneous ethanol injection (PEI) is less frequently used, and percutaneous acetic acid injection (PAI) has been mostly abandoned. Robust evidence showing benefit of one therapy versus another is lacking. Our aim was to evaluate the evidence comparing RFA, PEI and PAI using meta-analytical techniques.

METHODS

Literature search was undertaken until December 2008 to identify comparative studies evaluating survival, recurrence, complete necrosis of tumour and complications. Only randomized clinical trials and quasi-randomized studies were included. Adjusted indirect comparisons were made when direct comparative studies were insufficient.

RESULTS

Eight studies were identified: RFA vs. PEI (n=5), PAI vs. PEI (n=2) and RFA vs. PAI vs. PEI (n=1) including 1035 patients with nine comparisons. RFA was superior to PEI for survival (OR 0.52; 95% CI 0.35-0.78; p=0.001), complete necrosis of tumour and local recurrence. For tumours 2 cm RFA was not significantly better than PEI. PAI did not differ significantly from PEI for survival (OR 0.55; 95% CI 0.23-1.33; p=0.18), and local recurrence but required less sessions. PAI had similar outcomes, except local recurrence, to RFA in the direct and indirect comparison.

CONCLUSIONS

RFA seems to be a superior ablative therapy than PEI for HCC, particularly for tumours >2 cm. PAI did not differ significantly from PEI for all the outcomes evaluated. RFA and PAI have similar survival rates. For tumours 2 cm outcome benefits comparing RFA and PEI are similar. PAI needs re-evaluation versus both PEI and RFA for tumours 2 cm.

Evidence-based diagnosis and locoregional therapy for hepatocellular carcinoma

Early identification of hepatocellular carcinoma (HCC) is crucial to improving the results of therapy and for patients to be eligible for liver transplantation. Recent advances in noninvasive imaging technology include various techniques of harmonic ultrasound, new ultrasound contrast agents, multislice helical computed tomography and rapid high-quality magnetic resonance. The imaging diagnosis relies on the hallmark of arterial hypervascularity with portal venous washout. Since the use of better radiological techniques has improved the accuracy of noninvasive diagnosis, the role of liver biopsy in the diagnosis of HCC has declined. With recent advances in genomics and proteomics, a great number of potential markers have been identified and developed as new candidate markers for HCC. Locoregional therapies currently constitute the best options for early nonsurgical treatment of HCC. Percutaneous ethanol injection shows similar results to resection surgery for single tumors less than 3 cm in diameter. Radiofrequency ablation is superior to percutaneous ethanol injection in terms of local recurrence. Transarterial chemoembolization is currently the most common approach for the management of HCC without curative options since it improves patient survival, but the optimal embolizing agent, length of interval between sessions and whether the chemotherapeutic agent has any effect have not yet been determined. Combining transarterial chemoembolization with antiangiogenic agents, as well as with other techniques, such as radiofrequency ablation, may improve the results. Injection of radioisotopes such as yttrium-90, via the hepatic artery, may be particularly useful in patients with portal vein thrombosis. Comparisons with other transarterial techniques are needed.