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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.
The liver
Published in Professor Sir Norman Williams, Professor P. Ronan O’Connell, Professor Andrew W. McCaskie, Bailey & Love's Short Practice of Surgery, 2018
Professor Sir Norman Williams, Professor P. Ronan O’Connell, Professor Andrew W. McCaskie
Radiofrequency ablation (RFA) is the most widely used ablative technique and relies on direct current transmission through tissue to generate heat and ablation of the tumour. Increasing lesion size leads to exponential increases in resistance to current, limiting the size of the effective ablation zone and explaining the increased risk of local recurrence and diminished survival with lesions >3 cm. Microwave ablation has been designed to overcome some of the limitations of RFA and offers higher intratumoural temperatures, larger tumour ablation volumes and faster ablation times. Despite this, local recurrence after microwave ablation has been reported at between 5% and 13%.
Cytoreduction of neuroendocrine tumors
Published in Demetrius Pertsemlidis, William B. Inabnet III, Michel Gagner, Endocrine Surgery, 2017
Locally ablative methods have been used in hepatic metastases of GEP-NETs alone or in combination with surgical resection. They can be applied percutaneously, during open or laparoscopic surgery, and include ablation with radiofrequency, microwaves, laser, or cryotherapy [9, 52]. Radiofrequency has been the most common modality, but microwaves may be more efficacious due to higher intratumoral temperatures. The number of publications on laser and microwave ablation in this setting is low, and cryotherapy has higher rates of complications than the other methods. Ablation can be considered when surgery is not applicable and the number of metastases is few; it can also be combined with surgical resections (Figure 50.1) [53]. Lesions close to large vessels may be treated, since the vessels are protected by cooling due to bloodstream effects, but the cooling can decrease the therapeutic effect. Ultrasound is often used for guidance, but thermosensitive MR systems for continuous monitoring of coagulative effects have been developed.
Microwave ablation of multifocal primary liver cancer guided by real-time 3.0T MRI
Published in International Journal of Hyperthermia, 2023
Fenghai Liu, Baozhou Hou, Zhuofu Li, Lei Zhang, Yingwen Zhou, Hao Bian, Zhaoyang Huo
Percutaneous ablation techniques, including microwave ablation (MWA) and radiofrequency ablation (RFA), have become important minimally invasive treatment options for liver cancer. Microwave ablation is a form of thermal ablation for the interventional treatment of cancer. Compared with RFA, microwave ablation has the advantages of high thermal efficiency, fast heating rate, and less influence from the ‘heat sink effect’ [7]. At present, the most widely used image-guiding devices include computed tomography (CT), ultrasound (US), etc. CT-guided intervention is easy to affect the intraoperative display of small lesions due to metal material artifacts, and there is some deviation in the determination of the ablation boundary of small lesions equal or less than 1.0 cm. Although sonographically guided percutaneous microwave ablation proved to be safe, fast and effective for the treatment of hepatocellular carcinoma, ultrasound guidance is easily interfered with by various factors such as gas, bone, and liver movement, and the gasification phenomenon generated during thermal ablation may affect the evaluation of the ablation area [8,9].
A novel ISM band reflector type applicator design for microwave ablation systems
Published in Electromagnetic Biology and Medicine, 2021
Caner Murat, Merih Palandoken, Irfan Kaya, Adnan Kaya
Microwave ablation process is a minimally invasive, non-ionizing method based on the cellular level heating of the region to be ablated with the high power localized microwave energy for the cancer treatment (Chaichanyut et al. 2013). The interaction of high microwave power with tumorous tissue causes the loss of cellular viability by raising the core temperature above 60°C (Chiang et al. 2014; Neira et al. 2018; Reimann et al. 2018; Tal and Leviatan 2017). For that purpose, it is necessary to heat the ablation zone up to nearly 60°C while avoiding the temperature to exceed beyond that temperature. Otherwise, it results the surgery duration and pain that the patient feels to increase (Boni et al. 2006; Diederich 2005; Liang et al. 2009). In order to generate a microwave power that is required to quickly heat tumorous cells around 60°C, it is necessary to constrain the electromagnetic radiation around the section of the microwave ablation probe contacting the biological target directly.
Four types of tumor progression after microwave ablation of single hepatocellular carcinoma of ≤5 cm: incidence, risk factors and clinical significance
Published in International Journal of Hyperthermia, 2021
Zhimei Huang, Zhixing Guo, Jiayan Ni, Mengxuan Zuo, Tianqi Zhang, Rong Ma, Chao An, Jinhua Huang
Hepatocellular carcinoma (HCC) is a common malignancy, ranking sixth among the most common cancers and third among the leading cause of cancer-related mortalities worldwide. Both morbidity and mortality from HCC are continuously increasing [1–3]. Treatment for HCC varies based on the Barcelona Clinic Liver Cancer (BCLC) staging, with treatments ranging from surgical resection, liver transplantation and local radical ablation therapy [4]. As a primary choice for local ablation for patients not suitable for resection, the advantages of microwave ablation (MWA) include a higher intratumoral temperature, short operation time and less dependence on electrical conductivities compared to radiofrequency ablation (RFA) [5–7]. However, post-ablation recurrence remains a relatively frequent occurrence after treatment with MWA, which may result in prognosis, with as high as 52% within 5 years [8–10]. Accumulated evidence demonstrates that untreated micrometastases from the primary tumor, the subsequent transportal spread along intrasegmental branches and vascular invasion contribute to the progression of a tumor in vivo [11], all of which are independent risk factors for survival prognosis.