Radiofrequency Ablation and Microwave Ablation in Liver Tumors: An Update

Abstract

This article provides an overview of radiofrequency ablation (RFA) and microwave ablation (MWA) for treatment of primary liver tumors and hepatic metastasis. Only studies reporting RFA and MWA safety and efficacy on liver were retained. We found 40 clinical studies that satisfied the inclusion criteria. RFA has become an established treatment modality because of its efficacy, reproducibility, low complication rates, and availability. MWA has several advantages over RFA, which may make it more attractive to treat hepatic tumors. According to the literature, the overall survival, local recurrence, complication rates, disease‐free survival, and mortality in patients with hepatocellular carcinoma (HCC) treated with RFA vary between 53.2 ± 3.0 months and 66 months, between 59.8% and 63.1%, between 2% and 10.5%, between 22.0 ± 2.6 months and 39 months, and between 0% and 1.2%, respectively. According to the literature, overall survival, local recurrence, complication rates, disease‐free survival, and mortality in patients with HCC treated with MWA (compared with RFA) vary between 22 months for focal lesion >3 cm (vs. 21 months) and 50 months for focal lesion ≤3 cm (vs. 27 months), between 5% (vs. 46.6%) and 17.8% (vs. 18.2%), between 2.2% (vs. 0%) and 61.5% (vs. 45.4%), between 14 months (vs. 10.5 months) and 22 months (vs. no data reported), and between 0% (vs. 0%) and 15% (vs. 36%), respectively. According to the literature, the overall survival, local recurrence, complication rates, and mortality in liver metastases patients treated with RFA (vs. MWA) are not statistically different for both the survival times from primary tumor diagnosis and survival times from ablation, between 10% (vs. 6%) and 35.7% (vs. 39.6), between 1.1% (vs. 3.1%) and 24% (vs. 27%), and between 0% (vs. 0%) and 2% (vs. 0.3%). MWA should be considered the technique of choice in selected patients, when the tumor is ≥3 cm in diameter or is close to large vessels, independent of its size. Implications for Practice Although technical features of the radiofrequency ablation (RFA) and microwave ablation (MWA) are similar, the differences arise from the physical phenomenon used to generate heat. RFA has become an established treatment modality because of its efficacy, reproducibility, low complication rates, and availability. MWA has several advantages over RFA, which may make it more attractive than RFA to treat hepatic tumors. The benefits of MWA are an improved convection profile, higher constant intratumoral temperatures, faster ablation times, and the ability to use multiple probes to treat multiple lesions simultaneously. MWA should be considered the technique of choice when the tumor is ≥3 cm in diameter or is close to large vessels, independent of its size.

MR-guided microwave ablation in hepatic malignancies: clinical experiences from 50 procedures

“…The ablation device is important for an efficient and reliable coagulation process and complete destruction of the target tissue. While MWA generally exhibits a higher and more homogeneous temperature distribution as compared to RFA, prolonged or insufficient ablations are less likely [26,27]. Regardless of the device used, accurate and precise applicator placement within the target lesion is key for treatment success.…”

How large is the periablational zone after radiofrequency and microwave ablation? Computer-based comparative study of two currently used clinical devices

“…Bench tests [2][3][4][5], pre-clinical [6,7] and clinical studies [6] have compared coagulation zone size and treatment outcomes after both energy modalities. While some recent pre-clinical and clinical studies have compared the pro-tumorigenic effects of RFA and MWA [8][9][10], only one recent ex vivo study indirectly compared the volume of the RFA/MWA transition zone, its relationship with residual thermal energy after ablation, and the effect of subsequent cooling on reducing the transition zone [11].…”

New Deployable Expandable Electrodes in the Electroporation Treatment in a Pig Model: A Feasibility and Usability Preliminary Study

“…The EP treatment is not associated with a change in the temperature of the exposed tissue, except for near the needles of the electrodes [5,6]; the treatment can be performed in "noble" structures, such as vessels and nerves, without risk of complication. Moreover, the collagen and vascular tissue structure do not undergo coagulative degeneration as observed with hyperthermic procedures, such as radiofrequency (RFA), microwave (MWA), high-intensity focused ultrasound (HIFU), and laser therapy [7]. RFA and MWA are the two most commonly used techniques for solid organs treatment [7,8].…”

“…Moreover, the collagen and vascular tissue structure do not undergo coagulative degeneration as observed with hyperthermic procedures, such as radiofrequency (RFA), microwave (MWA), high-intensity focused ultrasound (HIFU), and laser therapy [7]. RFA and MWA are the two most commonly used techniques for solid organs treatment [7,8]. They have the advantages of greater volume of cellular necrosis and lesser susceptibility to heat dissipation effects due to the presence of neighboring vessels.…”

“…They have the advantages of greater volume of cellular necrosis and lesser susceptibility to heat dissipation effects due to the presence of neighboring vessels. The main disadvantage is the increased risk of damaging nearby non-target organs [7,8]. However, for irreversible electroporation, it was reported that the increase of pulse application could determine both an efficacy increase of the treatment and associated thermal damage [5,6], limited to the area around the electrodes [5,6,9].…”