Actual role of radiofrequency ablation of liver metastases

Boosting Microwave Thermo-Dynamic Cancer Therapy of TiMOF via COF-Coating

Microwave (MW) dynamic therapy (MDT) can efficiently eliminate tumor residue resulting from MW thermal therapy. However, MDT is currently in its infancy, and luck of effective MDT sensiters severely limits its clinical therapeutic effect. Herein, based on TiMOF (TM), a high-efficiency MW sensitizer is designed for MW thermo-dynamic therapy. TM can generate heat and cytotoxic reacyive oxygen species (ROS) under MW irradiation and has the potential to be used as an MW sensitizer, while the suboptimal MW dynamic sensitization effect of TM limits its application. Inorder to improve the MW dynamic sensitization performance, a covalent organic framework (COF) with good stability and a large conjugate system is used to cover TM, which is conductive to electron and energy transfer, thus increasing the ROS generation rate and prolonging the ROS lifetime. In addition, loading Ni NPs endow nanomaterials with magnetic resonance imaging capabilities. Therefore, this work develops an MW sensitizer based on TM for the first time, and the mechanism of COF coating to enhance the MW dynamic sensitization of TM is preliminarily explored, which provides a new idea for the further development of MW sensitizer with great potential.

Pancreatic Cancer: Challenges and Opportunities in Locoregional Therapies

Simple Summary

Pancreatic cancer is a serious ongoing global health burden, with an overall 5-year survival rate of less than 5%. One major hurdle in the treatment of this disease is the predominantly elderly patient population, leading to their ineligibility for curative surgery and a low rate of successful outcomes. Systemic administration introduces chemo-agents throughout the body via the blood, attacking not only tumours but also healthy organs. When localised interventions are employed, chemo-agents are retained specifically at tumour site, minimizing unwanted toxicity. As a result, there is a growing interest in finding novel localised interventions as alternatives to systemic therapy. Here, we present a detailed review of current locoregional therapies used in pancreatic cancer therapy. This work aims to present a thorough guide for researchers and clinicians intended to employ established and novel localised interventions in the treatment of pancreatic cancer. Furthermore, we present our insights and opinions on the potential ideals to improve these tools.

Abstract

Pancreatic cancer (PC) remains the seventh leading cause of cancer-related deaths worldwide and the third in the United States, making it one of the most lethal solid malignancies. Unfortunately, the symptoms of this disease are not very apparent despite an increasing incidence rate. Therefore, at the time of diagnosis, 45% of patients have already developed metastatic tumours. Due to the aggressive nature of the pancreatic tumours, local interventions are required in addition to first-line treatments. Locoregional interventions affect a specific area of the pancreas to minimize local tumour recurrence and reduce the side effects on surrounding healthy tissues. However, compared to the number of new studies on systemic therapy, very little research has been conducted on localised interventions for PC. To address this unbalanced focus and to shed light on the tremendous potentials of locoregional therapies, this work will provide a detailed discussion of various localised treatment strategies. Most importantly, to the best of our knowledge, the aspect of localised drug delivery systems used in PC was unprecedentedly discussed in this work. This review is meant for researchers and clinicians considering utilizing local therapy for the effective treatment of PC, providing a thorough guide on recent advancements in research and clinical trials toward locoregional interventions, together with the authors’ insight into their potential improvements.

Temperature Plays an Essential Regulatory Role in the Tumor Immune Microenvironment

In recent years, emerging immunotherapy has been included in various malignant tumor treatment standards. Temperature has been considered to affect different pathophysiological reactions such as inflammation and cancer for a long time. However, in tumor immunology research, temperature is still rarely considered a significant variable. In this review, we discuss the effects of room temperature, body temperature, and the local tumor temperature on the tumor immune microenvironment from multiple levels and perspectives, and we discuss changes in the body's local and whole-body temperature under tumor conditions. We analyze the current use of ablation treatment-the reason for the opposite immune effect. We should pay more attention to the therapeutic potential of temperature and create a better antitumor microenvironment that can be combined with immunotherapy.

The blood cells in NSCLC and the changes after RFA

Lung cancer has attracted a lot of attention because of its high morbidity and mortality. The emergence of RFA provides a new treatment for unresectable NSCLC patients. In addition to killing in situ lung tumors, RFA also provides new immuno-activated antigens, for the treatment of lung cancer. It changes the tumor microenvironment and activates the entire immune system of patients. The peripheral blood cell count is easy to achieve and the blood cells are important in tumor immunity, which changes after RFA. On the one hand, the changes in blood cells identify the immune changes of NSCLC; on the other hand, it provides support and suspicion for the treatment of RFA.

A comparison between radiofrequency ablation combined with transarterial chemoembolization and surgical resection in hepatic carcinoma: A meta-analysis

Objective

This study determined whether the effect of combination therapy for hepatic carcinoma (HCC) is comparable to surgical resection (SR). According to the guidelines of the American Association for the Study of Liver Disease, radiofrequency ablation (RFA) and SR are recommended for early HCC. However, patients treated with RFA had worse long-term survival than those who received SR. Many studies utilizing the combination therapy with RFA and transarterial chemoembolization (TACE) have reported better prognosis as compared to RFA alone.

Materials and Methods

A comprehensive search in databases was conducted. Six retrospective studies and one cohort were enrolled in this meta-analysis. The overall survival (OS), disease-free survival (DFS), and major complications were compared between RFA plus TACE and SR. The pooled hazard ratio and 95% confidence interval (CI) were calculated and analyzed.

Results

After comparison, no significant difference in the OS and DFS at 1 and 3 years between the combination therapy and SR was observed (OS1: pooled relative risk [RR]: 0.82, 95% CI [0.56, 1.21]; OS3: pooled RR: 1.07, 95% CI [0.82, 1.39]; DFS1: pooled RR: 0.92, 95% CI [0.58, 1.45]; DFS3: pooled RR: 1.18, 95% CI [1.00, 1.40]). SR had better clinical outcomes than combination therapy with respect to long-term survival and disease progression (OS5: pooled RR: 1.12, 95% CI [1.03, 1.23]; DFS5: pooled RR: 1.15, 95% CI [1.03, 1.28]). Major complications were reduced with combination therapy (pooled RR: 0.46, 95% CI [0.25, 0.85]).

Conclusion

SR should remain as the first-line therapy for early HCC.

An analytical solution for temperature distributions in hepatic radiofrequency ablation incorporating the heat-sink effect of large vessels

Fast prediction of the local thermal field induced by radiofrequency ablation (RFA) plays a critical role in hepatic RFA therapy. At present, it is still a challenging task to calculate and visualize the temperature distribution of RFA in real-time, especially when the heat-sink effect of adjacent large vessels is taken into account. To achieve this, the current investigation presented an analytical solution to calculate the temperature in RFA with an execution time of 0.05 s for three dimensional thermal field reconstruction. The presented temperature distribution is a combination of temperatures in homogeneous tissue and a quantification of the heat-sink effect of adjacent blood vessels. Temperatures in homogeneous tissue is calculated from a simplified Pennes bioheat equation, where several weighting parameters in the temperature expression are determined based on some reference point temperatures from the numerical simulation. The heat-sink effect is quantified based on a temperature factor, which measures the temperature difference between the vessel and the heated tissue, and a distance factor, which measures the distance to the vessel. The proposed method is validated to be able to gain similar temperature distributions to the numerical simulation but with its computational time being orders of magnitude smaller than that of numerical simulation, which improves the efficiency of interactive planning of RFA.

Augmented visualization with depth perception cues to improve the surgeon's performance in minimally invasive surgery

Minimally invasive techniques, such as laparoscopy and radiofrequency ablation of tumors, bring important advantages in surgery: by minimizing incisions on the patient's body, they can reduce the hospitalization period and the risk of postoperative complications. Unfortunately, they come with drawbacks for surgeons, who have a restricted vision of the operation area through an indirect access and 2D images provided by a camera inserted in the body. Augmented reality provides an "X-ray vision" of the patient anatomy thanks to the visualization of the internal organs of the patient. In this way, surgeons are free from the task of mentally associating the content from CT images to the operative scene. We present a navigation system that supports surgeons in preoperative and intraoperative phases and an augmented reality system that superimposes virtual organs on the patient's body together with depth and distance information. We implemented a combination of visual and audio cues allowing the surgeon to improve the intervention precision and avoid the risk of damaging anatomical structures. The test scenarios proved the good efficacy and accuracy of the system. Moreover, tests in the operating room suggested some modifications to the tracking system to make it more robust with respect to occlusions. Graphical Abstract Augmented visualization in minimally invasive surgery.

Stereotactic body radiotherapy using the CyberKnife® system in the treatment of patients with liver metastases: state of the art

Background

The management of patients with liver metastases presents a challenging problem in clinical oncology. Patients with limited involvement of the liver may be suitable for surgical resection or local ablative techniques. Stereotactic body radiotherapy (SBRT) presents an emerging new technology that has shown high efficacy in ablating tumors at various disease sites.

Methods

A comprehensive literature search was performed to identify articles in regard to the SBRT in the treatment of patients with liver metastases.

Results

SBRT allows for the delivery of high-dose radiation in few fractions to the tumor with extreme accuracy, while minimizing the damage to normal surrounding tissue. The CyberKnife^® system is an image-guided robotic system that delivers SBRT, tracks tumors during respiration, and automatically adjusts treatment for any patient movement. The most frequently used indications for CyberKnife^® therapy are ≤5 liver metastases with maximum tumor sizes of 6 cm, no extrahepatic disease, good performance status, and adequate hepatic functions. Local control rates range from 70%-100% at 1 year and from 60%-90% at 2 years. Severe toxicity related to SBRT is uncommon - grade three side effects occur in less than 5% of cases. Despite excellent local control rates, out-of-field metastatic progression (out-of-field hepatic metastases and extrahepatic metastases) develops in a substantial proportion of patients after SBRT. Therefore, it seems essential to improve the selection of patients with liver metastases for SBRT.

Conclusion

The CyberKnife^® system presents an effective minimally invasive treatment modality for patients with hepatic oligometastases who are not suitable candidates for radical liver resection. The available data suggest that liver metastases can be treated by CyberKnife therapy with very low toxicity and excellent local control rates.

Science to Practice: Decrypting the Enigma of Ablation-induced Off-Target Effects-Is Network Pathway Analysis the Final Piece of the Puzzle?

As part of the ongoing effort to better understand and mitigate pro-oncogenic off-target effects of imaging-guided radiofrequency ablation (RFA), Kumar et al ( 1 ) used gene expression and network pathway analysis to examine the gene activation profiles in the peri-ablational zone after RFA in a breast adenocarcinoma liver metastasis animal model. Their analysis identified STAT3 (signal transducer and activator of transcription 3) as a key transcription factor upregulated in many signaling pathways in the peri-ablational zone after RFA. Consequently, the authors successfully used two STAT3 inhibitors to reduce distant tumor growth after treatment with RFA. By demonstrating that judicious and appropriate adjuvant therapy helped contain distant tumor growth caused by ablation, Kumar et al have managed to pave the road ahead for the definitive success of ablation.

Science to Practice: Molecular-targeted Drug Delivery in Combination with Radiofrequency Ablation of Liver Cancer: A Magic Bullet?

In an effort to improve the technical success rates and clinical outcomes of radiofrequency (RF) ablation, Yan et al validated the use of a tumor-penetrating peptide and thermosensitive doxorubicin (DOX)-loaded nanoparticles in combination with RF ablation in a hepatocellular carcinoma mouse model. By achieving higher chemotherapeutic drug concentrations in target lesions, fewer toxic effects, and improved survival end points in an animal tumor model, the authors conclude that superior tumor treatment with RF ablation is possible when combined with molecular-targeted drug delivery systems.

Percutaneous Dual-Switching Monopolar Radiofrequency Ablation Using a Separable Clustered Electrode: A Preliminary Study

Objective

To prospectively evaluate the safety and therapeutic effectiveness of dual-switching monopolar (DSM) radiofrequency ablation (RFA) for the treatment of hepatocellular carcinoma (HCC), and to retrospectively compare the results with those of single-switching monopolar (SSM) RFA in a historical control group.

Materials and Methods

This study was approved by the Institutional Review Board, with informed consent obtained from all patients. Fifty-two HCC patients who underwent DSM-RFA using a separable clustered electrode and dual-generators were prospectively enrolled. Technical parameters, complications, technical success, technical effectiveness, and local tumor progression (LTP) rates were evaluated by means of post-procedural and follow-up imaging. Thereafter, the outcome of DSM-RFA was compared with those of 249 retrospectively included HCC patients treated with SSM-RFA.

Results

There were two major complications (3.8%, 2/52) including pleural and pericardial effusion in the DSM-RFA group. The DSM-RFA yielded a 100% technical success rate, a 98.1% technical effectiveness rate, and a 4.3% 2-year LTP rate. In a retrospective comparison between the two groups, DSM-RFA created significantly larger ablation volume (4.20 ± 2.07 cm³/min vs. 3.03 ± 1.99 cm³/min, p < 0.01), and delivered higher energy (1.43 ± 0.37 kcal/min vs. 1.25 ± 0.50 kcal/min, p < 0.01) per given time, than SSM-RFA. There was no significant difference in major procedure-related complications (3.8% vs. 4.4%) and technical effectiveness rate (98.1% vs. 96.4%) between the two groups (p = 1.00). In addition, the 2-year LTP rate of DSM-RFA and SSM-RFA were 4.3% and 10.1%, respectively (p = 0.15).

Conclusion

DSM-RFA using a separable clustered electrode is safe and provides high local tumor control and good preliminary clinical outcome for small HCCs, which are at least comparable to those of SSM-RFA.

Tumor-penetrating Peptide-integrated Thermally Sensitive Liposomal Doxorubicin Enhances Efficacy of Radiofrequency Ablation in Liver Tumors

Purpose To investigate the role of a tumor-penetrating peptide (internalizing CRGDRGPDC [iRGD])-integrated thermally sensitive liposomal (TSL) doxorubicin (DOX) in combination with radiofrequency (RF) ablation of liver tumors in an animal model. Materials and Methods Approval from the institutional animal care and use committee was obtained. Characterization of iRGD-TSL-DOX was performed in vitro. Next, H22 liver adenocarcinomas were implanted in 138 mice in vivo. The DOX accumulation and cell apoptosis of iRGD-TSL-DOX and TSL-DOX with or without RF were evaluated (n = 5) at different time points after treatment with quantitative analysis or pathologic staining. Mice bearing tumors were randomized into the following six groups (each group, eight mice): no treatment, iRGD-TSL-DOX, TSL-DOX, RF alone, RF ablation followed by TSL-DOX at 30 minutes (TSL-DOX combined with RF), and RF ablation followed by iRGD-TSL-DOX (iRGD-TSL-DOX combined with RF). Kaplan-Meier method was used to estimate the survival curves and log-rank test was used for comparison with statistical software. Results DOX encapsulation efficiency in iRGD-TSL-DOX was 97.5% ± 1.3 (standard deviation) with temperature-dependent drug release capability confirmed in vitro. In vivo, the iRGD-TSL-DOX group had overall higher DOX concentration in the tumor and had maximal difference at 24 hours compared with TSL-DOX group (2.7-fold). RF caused more intense cell apoptosis at 24 hours (median, 65% vs 21%, respectively; P < .001). For end-point survival, the iRGD-TSL-DOX combined with RF group had better survival (median, 32 days) than TSL-DOX combined with RF (median, 27 days; P = .035) or RF alone (median, 21 days; P < .001). Conclusion Conjugation to iRGD helped to improve intratumoral DOX accumulation and further enhanced the activity of TSL-DOX in RF ablation of liver tumors. ^© RSNA, 2017 Online supplemental material is available for this article.

Aggressive tumor recurrence after radiofrequency ablation for hepatocellular carcinoma

Image-guided radiofrequency ablation (RFA) is an evolving and growing treatment option for patients with hepatocellular carcinoma (HCC) and hepatic metastasis. RFA offers significant advantages as it is less invasive than surgery and carries a low risk of major complications. However, serious complications, including aggressive tumor recurrence, may be observed during follow-up, and recently, mechanical or thermal damage during RFA has been proposed to be one of the causes of this kind of recurrence. Although the exact mechanism of this still remains unclear, physicians should be familiar with the imaging features of aggressive tumor recurrence after RFA for HCC and its risk factors. In addition, in order to prevent or minimize this newly recognized tumor recurrence, a modified RFA technique, combined RFA treatments with transarterial chemoembolization, and cryoablation can be used as alternative treatments. Ultimately, combining an understanding of this potential complication of RFA with an understanding of the possible risk factors for aggressive tumor recurrence and choosing alternative treatments are crucial to optimize clinical outcomes in each patient with HCC.

An injectable ionic hydrogel inducing high temperature hyperthermia for microwave tumor ablation

Microwave tumor ablation is of clinical significance and has been considered as a promising cancer minimally invasive therapy.

Non-Rigid Registration of Liver CT Images for CT-Guided Ablation of Liver Tumors

CT-guided percutaneous ablation for liver cancer treatment is a relevant technique for patients not eligible for surgery and with tumors that are inconspicuous on US imaging. The lack of real-time imaging and the use of a limited amount of CT contrast agent make targeting the tumor with the needle challenging. In this study, we evaluate a registration framework that allows the integration of diagnostic pre-operative contrast enhanced CT images and intra-operative non-contrast enhanced CT images to improve image guidance in the intervention. The liver and tumor are segmented in the pre-operative contrast enhanced CT images. Next, the contrast enhanced image is registered to the intra-operative CT images in a two-stage approach. First, the contrast-enhanced diagnostic image is non-rigidly registered to a non-contrast enhanced image that is conventionally acquired at the start of the intervention. In case the initial registration is not sufficiently accurate, a refinement step is applied using non-rigid registration method with a local rigidity term. In the second stage, the intra-operative CT-images that are used to check the needle position, which often consist of only a few slices, are registered rigidly to the intra-operative image that was acquired at the start of the intervention. Subsequently, the diagnostic image is registered to the current intra-operative image, using both transformations, this allows the visualization of the tumor region extracted from pre-operative data in the intra-operative CT images containing needle. The method is evaluated on imaging data of 19 patients at the Erasmus MC. Quantitative evaluation is performed using the Dice metric, mean surface distance of the liver border and corresponding landmarks in the diagnostic and the intra-operative images. The registration of the diagnostic CT image to the initial intra-operative CT image did not require a refinement step in 13 cases. For those cases, the resulting registration had a Dice coefficient for the livers of 91.4%, a mean surface distance of 4.4 mm and a mean distance between corresponding landmarks of 4.7 mm. For the three cases with a refinement step, the registration result significantly improved (p<0.05) compared to the result of the initial non rigid registration method (DICE of 90.3% vs 71.3% and mean surface distance of 5.1 mm vs 11.3 mm and mean distance between corresponding landmark of 6.4 mm vs 10.2 mm). The registration of the preoperative data with the needle image in 16 cases yielded a DICE of 90.1% and a mean surface distance of 5.2 mm. The remaining three cases with DICE smaller than 80% were classified as unsuccessful registration. The results show that this is promising tool for liver image registration in interventional radiology.

An automatic registration method for pre- and post-interventional CT images for assessing treatment success in liver RFA treatment

PURPOSE

In image-guided radio frequency ablation for liver cancer treatment, pre- and post-interventional CT images are typically used to verify the treatment success of the therapy. In current clinical practice, the tumor zone in the diagnostic, preinterventional images is mentally or manually mapped to the ablation zone in the post-interventional images to decide success of the treatment. However, liver deformation and differences in image quality as well as in texture of the ablation zone and the tumor area make the mental or manual registration a challenging task. Purpose of this paper is to develop an automatic framework to register the pre-interventional image to the post-interventional image.

METHODS

The authors propose a registration approach enabling a nonrigid deformation of the tumor to the ablation zone, while keeping locally rigid deformation of the tumor area. The method was evaluated on CT images of 38 patient datasets from Erasmus MC. The evaluation is based on Dice coefficients of the liver segmentation on both the pre-interventional and post-interventional images, and mean distances between the liver segmentations. Additionally, residual distances after registration between corresponding landmarks and local mean surface distance in the images were computed.

RESULTS

The results show that rigid registration gives a Dice coefficient of 87.9%, a mean distance of the liver surfaces of 5.53 mm, and a landmark error of 5.38 mm, while non-rigid registration with local rigid deformation has a Dice coefficient of 92.2%, a mean distance between the liver segmentation boundaries near the tumor area of 3.83 mm, and a landmark error of 2.91 mm, where a part of this error can be attributed to the slice spacing in the authors' CT images.

CONCLUSIONS

This method is thus a promising tool to assess the success of RFA liver cancer treatment.

Automatic Liver Segmentation on Volumetric CT Images Using Supervoxel-Based Graph Cuts

Accurate segmentation of liver from abdominal CT scans is critical for computer-assisted diagnosis and therapy. Despite many years of research, automatic liver segmentation remains a challenging task. In this paper, a novel method was proposed for automatic delineation of liver on CT volume images using supervoxel-based graph cuts. To extract the liver volume of interest (VOI), the region of abdomen was firstly determined based on maximum intensity projection (MIP) and thresholding methods. Then, the patient-specific liver VOI was extracted from the region of abdomen by using a histogram-based adaptive thresholding method and morphological operations. The supervoxels of the liver VOI were generated using the simple linear iterative clustering (SLIC) method. The foreground/background seeds for graph cuts were generated on the largest liver slice, and the graph cuts algorithm was applied to the VOI supervoxels. Thirty abdominal CT images were used to evaluate the accuracy and efficiency of the proposed algorithm. Experimental results show that the proposed method can detect the liver accurately with significant reduction of processing time, especially when dealing with diseased liver cases.

Recent Advances in Tumor Ablation for Hepatocellular Carcinoma

Image-guided tumor ablation for early stage hepatocellular carcinoma (HCC) is an accepted non-surgical treatment that provides excellent local tumor control and favorable survival benefit. This review summarizes the recent advances in tumor ablation for HCC. Diagnostic imaging and molecular biology of HCC has recently undergone marked improvements. Second-generation ultrasonography (US) contrast agents, new computed tomography (CT) techniques, and liver-specific contrast agents for magnetic resonance imaging (MRI) have enabled the early detection of smaller and inconspicuous HCC lesions. Various imaging-guidance tools that incorporate imaging-fusion between real-time US and CT/MRI, that are now common for percutaneous tumor ablation, have increased operator confidence in the accurate targeting of technically difficult tumors. In addition to radiofrequency ablation (RFA), various therapeutic modalities including microwave ablation, irreversible electroporation, and high-intensity focused ultrasound ablation have attracted attention as alternative energy sources for effective locoregional treatment of HCC. In addition, combined treatment with RFA and chemoembolization or molecular agents may be able to overcome the limitation of advanced or large tumors. Finally, understanding of the biological mechanisms and advances in therapy associated with tumor ablation will be important for successful tumor control. All these advances in tumor ablation for HCC will result in significant improvement in the prognosis of HCC patients. In this review, we primarily focus on recent advances in molecular tumor biology, diagnosis, imaging-guidance tools, and therapeutic modalities, and refer to the current status and future perspectives for tumor ablation for HCC.

Magnetic resonance imaging of the liver after loco-regional and systemic therapy

Assessment of tumor response is crucial in determining the effectiveness of loco-regional and systemic therapy, and for determining the need for subsequent treatment. The ultimate goal is to improve patient's survival. Changes in tumor size and enhancement after therapy may not be detected early by the traditional response criteria. Tumor response is better assessed in the entire tumor volume rather than in a single axial plane. The purpose of this article is to familiarize the reader with early treatment response assessed by anatomic and volumetric functional magnetic resonance imaging metrics of the liver after loco-regional and systemic therapy.

Neural stem cell-mediated intratumoral delivery of gold nanorods improves photothermal therapy

Plasmonic photothermal therapy utilizes biologically inert gold nanorods (AuNRs) as tumor-localized antennas that convert light into heat capable of eliminating cancerous tissue. This approach has lower morbidity than surgical resection and can potentially synergize with other treatment modalities including chemotherapy and immunotherapy. Despite these advantages, it is still challenging to obtain heating of the entire tumor mass while avoiding unnecessary collateral damage to surrounding healthy tissue. It is therefore critical to identify innovative methods to distribute an effective concentration of AuNRs throughout tumors without depositing them in surrounding healthy tissue. Here we demonstrate that AuNR-loaded, tumor-tropic neural stem cells (NSCs) can be used to improve the intratumoral distribution of AuNRs. A simple UV-vis technique for measuring AuNR loading within NSCs was established. It was then confirmed that NSC viability is unimpaired following AuNR loading and that NSCs retain AuNRs long enough to migrate throughout tumors. We then demonstrate that intratumoral injections of AuNR-loaded NSCs are more efficacious than free AuNR injections, as evidenced by reduced recurrence rates of triple-negative breast cancer (MDA-MB-231) xenografts following NIR exposure. Finally, we demonstrate that the distribution of AuNRs throughout the tumors is improved when transported by NSCs, likely resulting in the improved efficacy of AuNR-loaded NSCs as compared to free AuNRs. These findings highlight the advantage of combining cellular therapies and nanotechnology to generate more effective cancer treatments.

Neoadjuvant TACE before laser induced thermotherapy (LITT) in the treatment of non-colorectal non-breast cancer liver metastases: feasibility and survival rates

PURPOSE

To evaluate safety, feasibility and overall survival rates for transarterial chemoembolization (TACE) alone or combined with MR-guided laser-induced-thermotherapy (LITT) in liver metastases of non-colorectal and non-breast cancer origin.

METHODS AND MATERIALS

Included were patients with unresectable non-colorectal non-breast cancer liver metastases with progression under systemic chemotherapy. Excluded were patients with Karnofsky score ≤ 70, respiratory, renal and cardiovascular failure, and general TACE contraindications. TACE using Mitomycin alone, Mitomycin-Gemcitabine or Mitomycin-Gemcitabine-Cisplatin was performed to all patients. After TACE 146 metastases were ablated with MR-guided LITT. To be eligible for LITT metastases should be < 5 cm in size and ≤ 5 in number. Tumor response was evaluated using MRI according to RECIST. Survival was evaluated using Kaplan-Meier analysis.

RESULTS

A total of 110 patients (mean age 59.2 years) with 371 metastases received TACE (mean 5.4 sessions/patient, n=110) with 76 (69%) receiving LITT (mean 1.6 session/patient) afterwards. TACE resulted in a mean decrease of mean maximum diameter of 52% ± 26.6 and volume change of -68.5% ± 22.9 in the 25 patients (23%) with partial response. Stable disease (n=59, 54%). Progressive disease (n=26, 23%). The RECIST outcome after LITT showed complete response (n=13, 17%), partial response (n=1, 1%), stable situation (n=41, 54%) and progressive disease (n=21, 28%). The mean time to progression (TTP) was 8.6 months. Median survival of all patients was 21.1 months.

CONCLUSION

TACE with different protocols alone and in combination with LITT is a feasible palliative treatment option resulting in a median survival of 21.1 months for unresectable liver metastases of non-colorectal and non-breast cancer origin.

Fiber-optic chirped FBG for distributed thermal monitoring of ex-vivo radiofrequency ablation of liver

A linearly chirped fiber Bragg grating (LCFBG) has been used as a temperature sensor for online monitoring of radiofrequency thermal ablation (RFTA). The LCFBG acts as a distributed sensor, with spatial resolution of 75 μm. A white-light setup that records the LCFBG spectrum estimates the temperature profile in real time. Three RFTA experiments have been performed ex-vivo on porcine liver measuring the radial temperature distribution during the heating process. The analysis of thermal maps quantifies the spatial heat distribution along the measurement axis and determines the ablation efficiency.

Preparing the anatomical model for ablation of unresectable liver tumor

INTRODUCTION

Nowadays the best treatment of the primary and secondary hepatic tumor is surgical resection, but only 5-15% of all patient with hepatocellular carcinoma and 20-25% of all patients with liver metastases are indicated for resection. In these cases some kind of ablation and other technique could be used.

AIM

To present the methodology of preparing the anatomical model for ablation of unresectable liver tumor.

MATERIAL AND METHODS

The presented method is based on abdomen computed tomography (CT) dynamic examination. Three methods of segmentation are used: rolling vector for liver volume, modified Frangi filter for liver vessels, and fuzzy expert system with initial region-of-interest anisotropic filtration for liver metastases. Segmentation results are the input data for creating 3D anatomical models in the form of B-spline curves and surfaces performing the surface global interpolation algorithm. A graphical user interface for presentation and evaluation of models, presented in color against DICOM images in grayscale, is designed and implemented.

RESULTS

The proposed approach was tested on 20 abdominal CT obtained from the Department of Clinical Radiology of Silesian Medical University. The lack of a "gold standard" provides for the correction of the results.

CONCLUSIONS

Preparation of the anatomical model is one of the important early stages of the use of image-based navigation systems. This process could not take place in a fully automatic manner and verification of the results obtained is performed by the radiologist. Using the above anatomical model in surgical workflow is presented.

Thermal ablation of tumours: biological mechanisms and advances in therapy

Minimally invasive thermal ablation of tumours has become common since the advent of modern imaging. From the ablation of small, unresectable tumours to experimental therapies, percutaneous radiofrequency ablation, microwave ablation, cryoablation and irreversible electroporation have an increasing role in the treatment of solid neoplasms. This Opinion article examines the mechanisms of tumour cell death that are induced by the most common thermoablative techniques and discusses the rapidly developing areas of research in the field, including combinatorial ablation and immunotherapy, synergy with conventional chemotherapy and radiation, and the development of a new ablation modality in irreversible electroporation.

Radiofrequency energy in surgery: state of the art

Over a period of more than 100 years, radiofrequency energy has been introduced in many fields and applications in medicine. At present, radiofrequency constitutes the basis of numerous medical devices employed in almost all medical specialties. It is particularly applicable and valuable in various minimally invasive procedures for its locally focused effects. Radiofrequency energy is a technical term established to describe high-frequency alternating electrical currents (with a frequency ranging from 300 kHz to 3 MHz) and their impact on biological tissue. The application of RF energy causes controlled tissue heating with consequent cell protein denaturation and desiccation, which leads to cell death and tissue destruction. The primary principle of radiofrequency is that the generated heat can be used to cut, coagulate or induce metabolic processes in the target tissue. The authors of this paper offer a comprehensive and compact review of the definition, history, physics, biological principles and applications of radiofrequency energy in current surgery.

Bile aspiration and hydrodissection to prevent complications in hepatic RFA close to the gallbladder

BACKGROUND

Radiofrequency ablation (RFA) of liver tumors is a mainstay of interventional oncology. Its application, however, is limited by tumor size and location with lesions located within 1 cm to the gallbladder being at increased risk for complications.

PURPOSE

To evaluate the safety of hepatic RFA after bile aspiration with or without additional hydrodissection for lesions adjacent to the gallbladder.

MATERIAL AND METHODS

Six patients undergoing RFA of tumors with a distance of less than 1 cm to the gallbladder were retrospectively identified from a computer database. All patients underwent RFA combined with percutaneous bile aspiration from the gallbladder. In four patients additional hydrodissection was performed. Technical success and post-interventional complications were assessed by reviewing images and patient charts.

RESULTS

Ablations were successfully completed in 5/6 patients. In one patient with incomplete ablation re-ablation was performed 2 months after the initial procedure. Minor complications occurred in three patients, including right-sided pleural effusion, hematoma in the gallbladder fossa, and intralesional hemorrhage in one patient each. There were no cases with cholecystitis or damage to the gallbladder during follow-up.

CONCLUSION

Bile aspiration with or without additional hydrodissection permits safe RFA of tumors located close to the gallbladder.

Bimodal electric tissue ablation (BETA)--effect of reversing the polarity of the direct current on the size of ablation

BACKGROUND

Bimodal electric tissue ablation (BETA) is a new technique that uses the direct current in electrolysis to improve the efficacy of radio frequency (RF) ablation. It was hypothesized that attaching the cathode of the electrolytic circuit to the RF electrode will increase the tissue hydration, therefore delaying tissue desiccation during ablation. Consequently, the ablation process can continue for a longer period of time and produce larger ablations. This hypothesis was tested by reversing the polarity of the electrolytic circuit, which theoretically would cause tissue desiccation and therefore produce smaller ablations. This new setup is called reversed polarity bimodal electric ablation (RP-BEA).

MATERIALS AND METHODS

Three types of ablations standard radiofrequency ablation (RFA), BETA, and RP-BEA) were tested in a pig liver model. In BETA and RP-BEA, 9 V of direct current were provided for 10 min, after which the rf generator were switched on and both electrical circuits allowed to run concurrently. In all three setups, ablations were continued until "roll-off." The size of ablation was measured and compared with each other.

RESULTS

The duration of ablation was significantly shorted in RP-BEA compared with standard RFA and BETA (48 s verus 148 s and 84 s, respectively, P = 0.004). The sizes of ablations in RP-BEA were also significantly smaller compared with standard RFA and BETA-skin.

CONCLUSION

RP-BEA caused tissue desiccation resulting in a shorter duration of ablation and smaller ablations. Therefore, the theory that BETA increases ablation size due to the effects of increased tissue hydration around the rf electrode is correct.

More than just tumor destruction: immunomodulation by thermal ablation of cancer

Over the past decades, thermoablative techniques for the therapy of localized tumors have gained importance in the treatment of patients not eligible for surgical resection. Anecdotal reports have described spontaneous distant tumor regression after thermal ablation, indicating a possible involvement of the immune system, hence an induction of antitumor immunity after thermoinduced therapy. In recent years, a growing body of evidence for modulation of both adaptive and innate immunity, as well as for the induction of danger signals through thermoablation, has emerged. Induced immune responses, however, are mostly weak and not sufficient for the complete eradication of established tumors or durable prevention of disease progression, and combination therapies with immunomodulating drugs are being evaluated with promising results. This article aims to summarize published findings on immune modulation through radiofrequency ablation, cryoablation, microwave ablation therapy, high-intensity focused ultrasound, and laser-induced thermotherapy.

Elevated serum levels of heat shock protein 70 can be detected after radiofrequency ablation

Due to their adjuvant effect and their ability to chaperone tumor-associated peptides, heat shock proteins constitute a potent alarm signal for the immune system and can lead to activation of anti-tumor T-cell immunity. Radiofrequency ablation has been reported to induce heat shock protein expression especially that of heat shock protein 70 in sublethally damaged tumor cells. In this study, we evaluated the release of heat shock protein 70 into the serum of cancer-bearing patients directly after radiofrequency ablation. Sera of 22 patients undergoing radiofrequency ablation for the treatment of primary and secondary malignancies of the liver, kidney, and lung, as well as control sera of 20 patients undergoing diagnostic liver biopsy were analyzed using a manufactured heat shock protein 70 ELISA. A significant increase in serum levels of heat shock protein 70 was detectable in the patient cohort 1 day after radiofrequency ablation. More than a twofold increase was observed in nine out of 22 patients, which tended to correlate with favorable clinical outcome. No patient of the control group revealed a comparable increase. Radiofrequency ablation can lead to a release of heat shock protein 70 into the serum, which is transiently detectable 1 day after treatment. Elevated heat shock protein 70 serum levels may constitute a biomarker for favorable clinical outcome.

Systematic review and meta-analysis of survival and disease recurrence after radiofrequency ablation for hepatocellular carcinoma

BACKGROUND

Despite being one of the commonest causes of cancer-related death around the world, only 20 per cent of hepatocellular carcinomas (HCCs) are amenable to curative treatment (surgical resection or liver transplantation). Radiofrequency ablation (RFA) has emerged as a popular therapy for unresectable HCC. There is evidence that the disparity in survival after curative RFA and surgery for HCC, especially tumours smaller than 3 cm in diameter, is narrowing. This review examined the survival and disease recurrence rates after RFA for HCC over the past decade.

METHODS

A systematic review was conducted using MEDLINE, Embase, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, Cochrane Methodology Register and the Database of Abstracts of Reviews of Effects from January 2000 until November 2010. Papers reporting on patients with HCC who were treated with RFA, either in comparison or in combination with other interventions, such as surgery or percutaneous ethanol injection (PEI), were eligible for inclusion. Outcome data collected were overall survival, disease-free survival and disease recurrence rates. Only randomized controlled trials (RCTs), quasi-RCTs and non-randomized comparative studies with more than 12 months' follow-up were included.

RESULTS

Forty-three articles, including 12 RCTs, were included in the review. The majority of the articles reported the use of RFA for unresectable HCC, often in combination with other treatments such as PEI, transarterial chemoembolization and/or surgery. Overall and disease-free survival rates continue to improve, despite an increase in the size and numbers of tumours treated. More recently some clinicians have used RFA to treat selected patients with resectable HCC, with good outcomes.

CONCLUSION

RFA provides a valuable treatment option for patients with unresectable HCC. It improves survival in those previously considered to have advanced disease. As progress continues to be made, RFA is gradually being used to treat resectable HCC.

Efficacy and feasibility of radiofrequency ablation for liver metastases from gastric adenocarcinoma

PURPOSE

Optimal treatment for liver metastases from gastric cancer remains a matter of debate. The aim of our study is to evaluate the efficacy of radiofrequency ablation (RFA) for the treatment of liver-only metastases from gastric adenocarcinoma.

MATERIALS AND METHODS

We retrospectively reviewed medical records of 29 patients who developed liver-only metastases from gastric adenocarcinoma and subsequently underwent gastric resection and RFA (n = 20) or gastric resection and systemic chemotherapy (n = 9) between January 1995 and February 2008. Overall survival was estimated using the Kaplan-Meier method, and was compared using the log rank test to evaluate RFA efficacy.

RESULTS

Twenty patients who underwent RFA showed a median overall survival of 30.7 months (range: 2.9 to 90.9 months), a median progression-free survival of 6.8 months (range: 0.8 to 45.2 months), and median overall one-, three-, and five-year survival rates were 66.8%, 40.1%, and 16.1% respectively. The RFA group showed a 76% decreased death rate compared to the chemotherapy-only group (30.7 months versus 7 months, hazard ratio, 0.24; p = 0.004). Most patients tolerated RFA well, and complications were found to be minor (transient fever (20%) and/or right upper quadrant pain (25%)). One case of treatment-related death occurred due to sepsis that originated from a liver abscess at the ablation site.

CONCLUSIONS

The data suggest that a use of RFA as a liver-directed treatment may provide greater survival benefit than chemotherapy and is an alternative option for the treatment of liver-only metastases from gastric cancer.

Multipolar radiofrequency ablation using internally cooled electrodes in ex vivo bovine liver: correlation between volume of coagulation and amount of applied energy

PURPOSE

To evaluate the relationship between applied energy and volume of coagulation induced by multipolar radiofrequency (RF) ablation.

METHODS AND MATERIALS

Multipolar RF ablations (n=80) were performed in ex vivo bovine liver. Three bipolar applicators with two electrodes located on each applicator shaft were placed in a triangular array. The power-output (75-225 W) and the distance between the different applicators (2, 3, 4, 5 cm) were systematically varied. The volume of confluent white coagulation and the amount of applied energy were assessed. Based on our experimental data the relationship between the volume of coagulation and applied energy was assessed by nonlinear regression analysis. The variability explained by the model was determined by the parameter r(2).

RESULTS

The volume of coagulation increases with higher amounts of applied energy. The maximum amount of energy was applied at a power-output of 75 W and an applicator distance of 5 cm. The corresponding maximum volume of coagulation was 324 cm(3) and required an application of 453 kJ. The relationship between amount of applied energy (E) and volume (V) of coagulation can be described by the function, V=4.39E(0.7) (r(2)=0.88). By approximation the volume of coagulation can be calculated by the linear function V=0.61E+40.7 (r(2)=0.87).

CONCLUSION

Ex vivo the relationship between volume of coagulation and amount of applied energy can be described by mathematical modeling. The amount of applied energy correlates to the volume of coagulation and may be a useful parameter to monitor multipolar RF ablation.

Hepatic tumor ablation

Ablation of liver tumors is part of a multimodality liver-directed strategy in the treatment of various tumors. The goal of ablation is complete tumor destruction, and ultimately improvement of quality and quantity of life for the patient. Technology is evolving rapidly, with important improvements in efficacy. The current state of ablation technology and indications for ablation are described in this review.

Fast Estimation of the Vascular Cooling in RFA Based on Numerical Simulation

We present a novel technique to predict the outcome of an RF ablation, including the vascular cooling effect. The main idea is to separate the problem into a patient independent part, which has to be performed only once for every applicator model and generator setting, and a patient dependent part, which can be performed very fast. The patient independent part fills a look-up table of the cooling effects of blood vessels, depending on the vessel radius and the distance of the RF applicator from the vessel, using a numerical simulation of the ablation process. The patient dependent part, on the other hand, only consists of a number of table look-up processes. The paper presents this main idea, along with the required steps for its implementation. First results of the computation and the related ex-vivo evaluation are presented and discussed. The paper concludes with future extensions and improvements of the approach.

Fast Estimation of the Vascular Cooling in RFA Based on Numerical Simulation

We present a novel technique to predict the outcome of an RF ablation, including the vascular cooling effect. The main idea is to separate the problem into a patient independent part, which has to be performed only once for every applicator model and generator setting, and a patient dependent part, which can be performed very fast. The patient independent part fills a look-up table of the cooling effects of blood vessels, depending on the vessel radius and the distance of the RF applicator from the vessel, using a numerical simulation of the ablation process. The patient dependent part, on the other hand, only consists of a number of table look-up processes. The paper presents this main idea, along with the required steps for its implementation. First results of the computation and the related ex-vivo evaluation are presented and discussed. The paper concludes with future extensions and improvements of the approach.

Breast cancer liver metastases: US-guided percutaneous radiofrequency ablation--intermediate and long-term survival rates

PURPOSE

To retrospectively assess the local control and intermediate- and long-term survival of patients with liver metastases from breast cancer who have undergone percutaneous ultrasonography (US)-guided radiofrequency (RF) ablation.

MATERIALS AND METHODS

This study was approved by the hospital ethics committee, and all patients provided written informed consent. RF ablation was used to treat 87 breast cancer liver metastases (mean diameter, 2.5 cm) in 52 female patients (median age, 55 years). Inclusion criteria were as follows: fewer than five tumors, maximum tumor diameter of 5 cm or smaller, and disease either confined to the liver or stable with medical therapy. Forty-five (90%) of 50 patients had previously undergone chemotherapy, hormonal therapy, or both, and had no response or an incomplete response to the treatment. Contrast material-enhanced computed tomography and US were performed to evaluate complications and technical success and to assess for local tumor progression during follow-up. The Kaplan-Meier method was used to assess survival, and results were compared between groups with a log-rank test. Cox regression analysis was used to assess independent prognostic factors that affected survival.

RESULTS

Complete tumor necrosis was achieved in 97% of tumors. Two (4%) minor complications occurred. Median time to follow-up from diagnosis of liver metastasis and from RF ablation was 37.2 and 19.1 months, respectively. Local tumor progression occurred in 25% of patients. New intrahepatic metastases developed in 53% of patients. From the time of first RF ablation, overall median survival time and 5-year survival rate were 29.9 months and 27%, respectively. From the time the first liver metastasis was diagnosed, overall median survival time was 42 months, and the 5-year survival rate was 32%. Patients with tumors 2.5 cm in diameter or larger had a worse prognosis (hazard ratio, 2.1) than did patients with tumors smaller than 2.5 cm in diameter.

CONCLUSION

Survival rates in selected patients with breast cancer liver metastases treated with RF ablation are comparable to those reported in the literature that were achieved with surgery or laser ablation.