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Biliary Tract Cancer
Published in Pat Price, Karol Sikora, Treatment of Cancer, 2020
Hemant M. Kocher, Vincent S. Yip, Ajit T. Abraham
Photodynamic therapy (PDT) involves the intravenous administration of a photosensitizer such as sodium porfimer, which localizes preferentially in tumor tissue over 24–48 hours. Subsequent endoscopic laser illumination of the tumor bed with a specific wavelength of light activates the porfimer, generating oxygen free radicals and causing cancer-cell death. One prospective randomized trial of 39 patients comparing stenting plus PDT vs. stenting alone showed increased median survival (493 vs. 98 days), improved stabilization of Karnofsky performance status, less cholestasis, and better quality of life scores.97 But the larger UK Photostent-02 trial with 92 patients showed a shorter overall survival with PDT plus stenting compared to stenting alone (6.2 vs. 9.8 months; HR, 1.56; p = 0.048). Fewer patients (20%) in the PDT/stenting arm received subsequent chemotherapy than in the stenting alone arm (41%). Although overall survival was significantly improved among those who had chemotherapy compared with those who did not, adjusting for this does not completely explain the excess risk from PDT.98 Other local ablation strategies such as radiofrequency ablation and ethanol injection are unproven. Loco-regional therapies such as irreversible electroporation, transcatheter arterial chemoembolization, and radioembolization with91 Y microspheres need further evaluation with randomized trials.
Metastatic Colorectal Cancer
Published in Savio George Barreto, Shailesh V. Shrikhande, Dilemmas in Abdominal Surgery, 2020
Ganesh Nagarajan, Kaushal Kundalia
While a complete surgical resection is always the most desirable treatment for colorectal liver metastases, often ablative procedures are used as a standalone treatment, or in combination with surgery. This is usually preferred for lesions which are deep seated in the parenchyma which would otherwise need a lot of parenchymal sacrifice (large/formal anatomical resections for relatively small lesions). Previously, the only modality was radiofrequency ablation. The main drawback of this technique is a heat-sink effect which would result in inadequate and incomplete ablation of the lesions in close proximity of major blood vessels. Over the last few years, microwave ablation is being more commonly used in many centers. Electromagnetic waves agitate water molecules in tissue producing heat and friction and thus cell death. This technique is faster than radiofrequency ablation, has a wider zone of ablation, and has a lesser heat sink effect. One needs to be cautious regarding thermal damage along the tract if the technique is improper. Some centers have recently tried irreversible electroporation as an ablative modality with promising results but the costs are presently prohibitive.
Treatment of Metastatic Disease
Published in Peter Sagar, Andrew G. Hill, Charles H. Knowles, Stefan Post, Willem A. Bemelman, Patricia L. Roberts, Susan Galandiuk, John R.T. Monson, Michael R.B. Keighley, Norman S. Williams, Keighley & Williams’ Surgery of the Anus, Rectum and Colon, 2019
Jürgen Weitz, Carina Riediger, Annika Stange, Ralf-Thorsten Hoffmann, David Morris
There are two new emerging technologies in the field of minimally or even non-invasive therapies. One of these treatments is the so-called irreversible electroporation. The mechanism behind this therapy is that short electrical impulses are able to destabilise biological membranes by disturbing the electrical potential which can be measured across the membrane. This destabilisation causes defects within the membrane of a cell. Depending on the amount of energy that is applied, these defects can be reversible or irreversible. If the energy that is applied is high enough, a disintegration of the cell membrane will occur, which leads to a cell death. Only recently has the potential of IRE as an alternative to MWA and RFA been recognised. Due to the fact that IRE has no thermal effect, and the damage to the cellular lipid bilayer is either reversible or irreversible, the margins of the ablation are very precise, and structures in close proximity to the ablative zone (like bile ducts, vessels) are not destroyed. As in the other thermal ablative techniques, up to four electrodes have to be placed around the tumour, and the electrical pulses have to be started. There is only one system available on the market. This system uses pulses with 3,000 V and a maximum current of 50A. Unfortunately, IRE has a major disadvantage. Anaesthesia in these patients is very complex. Complete muscle relaxation is necessary, because the electrical pulses can cause severe muscle contractions and special care has to be taken due to the possibility of causing substantial cardiac arrhythmia. There is no consensus as to whether IRE is just another thermal ablation tool comparable to RFA and MWA or whether because of the advantages of the system, precise well-demarcated ablation zones with preservation of critical structures like bile ducts or vessels can qualify IRE as a more specific therapy.
Automated irreversible electroporated region prediction using deep neural network, a preliminary study for treatment planning
Published in Electromagnetic Biology and Medicine, 2022
Irreversible electroporation (IRE) is a new ablation technique with minimum thermal damage for cancer treatment. Prior studies have noted the importance of electric field intensity distribution during the successful IRE treatment (Adeyanju et al. 2012; Corovic et al. 2013; Edd and Davalos 2007; Khorasani 2021a, 2021b; Rubinsky et al. 2007). As mentioned in the literature review, tumor coverage with sufficient electric field intensity and cell kill probability are very important during IRE treatment. Treatment planning with the finite element analysis method is a way to calculate electric field intensity distribution and cell kill probability distribution before the IRE process to optimize the IRE parameters. Although, this way of calculating the irreversible electroporated region has some limitations. The present study was designed to predict the IRE region during the IRE process with deep neural network (DNN) as an automatic, fast, and accurate method.
Chemotherapy plus concurrent irreversible electroporation improved local tumor control in unresectable hilar cholangiocarcinoma compared with chemotherapy alone
Published in International Journal of Hyperthermia, 2021
Yangyang Ma, Zhixian Chen, Weibing Zhu, Jie Yu, Hui Ji, Xiaosong Tang, Huayan Yu, Liping Fan, Bing Liang, Rongrong Li, Jianyu Li, Zhonghai Li, Mao Lin, Lizhi Niu
Irreversible electroporation (IRE) is a novel tumor ablation that utilizes high-voltage pulses to construct permanent nanopores within the cellular membrane and results in apoptosis of the targeted cells [18]. The biggest advantage of IRE is that collagen fibers and other connective tissue components don’t degenerate during IRE ablation, therefore, important tissue structures within the ablation zone are not damaged, such as bile ducts, portal veins, and hepatic veins. Thus, IRE ablation may be a more appropriate choice for UHC. Moreover, most research on IRE has focused on delaying bile duct obstruction rather than reducing tumor size [19,20]. Furthermore, no significant improvement in long-term survival has been observed. Hence, it is unknown whether the addition of IRE to chemotherapy could improve local tumor control in UHC patients.
Experimental model of occluded biliary metal stent recanalization using irreversible electroporation via a tubular catheter
Published in International Journal of Hyperthermia, 2021
T. Rohan, T. Andrasina, T. Juza, P. Matkulcik, D. Červinka, I. Svobodova, V. Novotná, V. Bernard, V. Valek, S. Nahum Goldberg
Irreversible electroporation (IRE) is a relatively novel method for the percutaneous treatment of hepatic tumors [16]. IRE causes cell death and necrosis through cell membrane porosity induced by high-voltage microsecond pulses delivered to the tissue. The major touted benefits compared to thermal ablation is IRE’s potential low heat production with ablation shape and volume being independent of thermal conductivity and loss, with effects directed on cellular membranes affording relative sparing of bile ducts and blood vessels [17]. Yet, IRE is no longer considered a solely non-thermal ablation method as prior experiments have demonstrated that temperature production during IRE linearly correlates with delivered energy to the point that thermal coagulation can be observed at high IRE doses [17]. Moreover, IRE is highly susceptible to changes in local electrical conductivity – something that is likely to occur in the presence of metallic hardware [18].