Results of single-probe microwave ablation of metastatic liver cancer

Efficacy and safety of microwave ablation and radiofrequency ablation in the treatment of hepatocellular carcinoma: A systematic review and meta-analysis

BACKGROUND

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors. Surgical resection is often only possible in the early stages of HCC and among those with limited cirrhosis. Radiofrequency ablation and Microwave ablation are 2 main types of percutaneous thermal ablation for the treatment of HCC. The efficacy and safety between these 2 therapy methods are still under a debate.

OBJECTIVE

To compare the efficacy and safety of Radiofrequency ablation and Microwave ablation in treating HCC.

METHODS

PubMed, EMBASE, the Cochrane databases and Web of Science were systematically searched. We included randomized controlled trials and cohort studies comparing the efficacy and safety of Radiofrequency ablation and Microwave ablation in HCC patients. Outcome measures on local tumor progression, complete ablation, disease-free survival, overall survival, or major complications were compared between the 2 groups. The random effect model was used when there was significant heterogeneity between studies, otherwise the fixed effect model was used.

RESULTS

A total of 33 studies, involving a total of 4589 patients were identified, which included studies comprised 7 RCTs, 24 retrospective observational trials, and 2 prospective observational trial. Microwave ablation had a lower local tumor progression than Radiofrequency ablation in cohort studies (OR = 0.78, 95% CI 0.64-0.96, P = .02). Complete ablation rate of Microwave ablation was higher than that of Radiofrequency ablation in cohort studies (OR = 1.54, 95% CI 1.05-2.25, P = .03). There was no significant difference in overall survival and disease-free survival between the 2 groups. Meta-analysis showed that there was no significant difference in the main complications between Microwave ablation and Radiofrequency ablation.

CONCLUSIONS

Microwave ablation has higher complete ablation and lower local tumor progression than Radiofrequency ablation in the ablation treatment of HCC nodules. There was no significant difference in overall survival between the 2 therapy methods.

Microwave ablation compared with radiofrequency ablation for the treatment of liver cancer: a systematic review and meta-analysis

BACKGROUND

Guidelines have reported that although microwave ablation (MWA) has potential advantages over radiofrequency ablation (RFA), superiority in efficacy and safety remain unclear. Aim of the study is to compare MWA with RFA in the treatment of liver cancer.

METHODS

Meta-analysis was conducted according to the PRISMA guidelines for studies published from 2010 onwards. A random-effects model was used for the meta-analyses. Complete ablation (CA), local tumor progression (LTP), intrahepatic distant recurrence (IDR), and complications were analyzed.

RESULTS

Four randomized trials and 11 observational studies with a total of 2,169 patients met the inclusion criteria. Although overall analysis showed no significant difference in LTP between MWA and RFA, subgroup analysis including randomized trials for patients with hepatocellular cancer (HCC) demonstrated statistically decreased rates of LTP in favor of MWA (OR, 0.40; 95% CI, 0.18-0.92; p = 0.03). No significant differences were found between the two procedures in CA, IDR, complications, and tumor diameter less or larger than 3 cm.

CONCLUSIONS

MWA showed promising results and demonstrated better oncological outcomes in terms of LTP compared to RFA in patients with HCC. MWA can be utilized as the ablation method of choice in patients with HCC.

Microwave ablation for the removal of pharyngeal benign lesions: A prospective pilot case series

OBJECTIVE

We evaluated microwave ablation (MWA) for treatment of isolated pharyngeal benign lesions, in terms of technical feasibility, efficacy, and safety.

METHODS

The patients with pharyngeal benign lesions were treated with endoscopic MWA with a 2450-MHz single cooled-shaft microwave antenna and sent for histological examination. Postoperative pain intensity was measured via visual analogue scale (VAS) on the 12th hour and the third postoperative days.

RESULTS

Of the 137 patients with pharyngeal benign lesions who met the inclusion criteria. The most commonly involved site was the uvula (n = 66, 48.2%), followed by the lateral pharyngeal wall (n = 37, 27.0%), the nasopharyngeal posterior wall (n = 23, 16.8%) and the soft palate (n = 11, 8.0%). All of the procedures were completed using local anesthesia and were well-tolerated by the patients. The ablation time was 5-10 min, with an average duration of 6.3 ± 1.8 min. The most common pathology was papilloma (n = 96, 70.1%), followed by nasopharyngeal cysts (n = 21, 15.3%), polyp (n = 10, 7.3%), epidermoid cysts (n = 8, 5.8%) and Thornwaldt cysts (n = 2, 1.5%). The mean VAS pain score was 2.36 ± 1.08 on postoperative 12th hour and 1.21 ± 0.54 on postoperative third day. At the 6-month follow-up examination, there were no severe complications, such as recurrence, bleeding, or synechiae of the nasal cavity, eustachian tube injury, in any of the patients.

CONCLUSIONS

The MWA for the treatment of isolated pharyngeal benign lesion is feasible and alternative to conventional surgical methods, it allows excision of the lesion while providing hemostasis, involves only a short ablation time and has a very low risk of complications. Most of our patients well-tolerate the procedure, which may be performed under local anesthesia in the outpatient setting.

Microwave Ablation for the Removal of Benign Lesion of Nasal Cavity: "How I Do It"

Background

Isolated benign lesions of the nasal cavity are commonly seen in the rhinology clinic; their treatment using various therapies has been explored in several studies.

Methods

In this retrospective study, isolated lesions of the nasal cavity were removed from 47 patients using microwave ablation (MWA) with a 2450-MHz cooled MWA antenna and sent for histological examination.

Results

The most commonly involved site was the nasal septum (n = 21, 44.7%), followed by the inferior turbinate (n = 12, 25.5%), bulla ethmoidalis (n = 9, 19.1%), and uncinate process (n = 5, 10.6%). The most common pathology was hemangioma (n = 36, 76.6%), followed by nasal polyp (n = 9, 19.1%) and squamous papilloma (n = 2, 4.3%). All lesions were removed endoscopically using MWA in patients administered local anesthesia. The total duration of ablation was 5 to 10 minutes, with an average duration of 7.3 ± 2.6 minutes. Follow-up at 6 months revealed no severe complications, including no cases of recurrent epistaxis, septal perforation, or synechiae of the nasal cavity.

Conclusions

The advantages of MWA are its short ablation time and minimal complications. This was demonstrated in our study in which a single session of MWA was sufficient to excise the isolated lesion while providing hemostasis. Most of the patients well tolerated the procedure, which could be performed using local anesthesia in the outpatient setting.

Microwave ablation compared with radiofrequency ablation for treatment of hepatocellular carcinoma and liver metastases: a systematic review and meta-analysis

Purpose

Percutaneous ablation techniques, including microwave ablation (MWA) and radiofrequency ablation (RFA), have become important minimally invasive treatment options for liver cancer. This systematic review compared MWA with RFA for treatment of liver cancer.

Methods

The systematic review and meta-analysis followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A systematic search of MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials was conducted for randomized and observational studies published from 2006 onwards. A random-effects model was used for meta-analyses and local tumor progression (LTP), technique efficacy, overall survival (OS), disease-free survival (DFS), intrahepatic de novo lesions (IDL), extrahepatic metastases (EHM), length of stay (LOS), and complications were analyzed. Subgroup and sensitivity analyses were also conducted.

Results

Of 1379 studies identified, 28 randomized and observational studies met inclusion criteria. The main analysis demonstrated that LTP was significantly reduced by 30% with MWA versus RFA (RR=0.70; P=0.02) (all studies) and by 45% with MWA versus RFA (RR=0.55; P=0.007) (randomized studies only). There were no significant differences between MWA and RFA for other efficacy and safety outcomes. Higher frequency (2450 MHz) and larger tumor size (≥2.5 cm) are amongst variables that may be associated with improved outcomes for MWA. Sensitivity analyses were generally congruent with the main results.

Conclusion

MWA is at least as safe and effective as RFA for treating liver cancer and demonstrated significantly reduced LTP rates. Future studies should assess time and costs associated with these two treatment modalities.

Microwave ablation: state-of-the-art review

This paper reviews state-of-the-art microwave ablation (MWA) of tumors. MWA is a novel method for treating inoperable tumors, ie, tumors that cannot be treated surgically. However, patients generally choose removal of the tumor by conventional techniques. A literature review of MWA for breast, liver, lung, and kidney tumors is reported here, with tabulation of our findings according to the type of technique used, with a detailed description of the time, type of microwave generator used, and number of patients treated with MWA. In some cases, the subjects were not human patients, but pig or bovine liver specimens. MWA is a technique that has proved to be promising and likely to be used increasingly in the ablation of cancerous tumors. However, MWA needs to be used more widely to establish itself as a common tool in the treatment of inoperable tumors.

Interventional oncologic approaches to liver metastases

Metastatic liver disease is the most common cause of death in cancer patients. Complete surgical resection is currently considered the only curative treatment, with only about 25% of patients being amenable to surgery. Therefore, a variety of interventional oncologic techniques have been developed for treating secondary liver malignancies. The aim of these therapies is either to allow patients with unresectable tumors to become surgical candidates, provide curative treatment options in nonsurgical candidates, or improve survival in a palliative or even curative approach. Among these interventional therapies are transcatheter therapies such as portal vein embolization, hepatic artery infusion chemotherapy, transarterial chemoembolization, and radioembolization, as well as interstitial techniques, particularly radiofrequency ablation as the most commonly applied technique. The rationale, application and clinical results of each of these techniques are reviewed on the basis of the current literature. Future prospects such as gene therapy and immunotherapy are introduced.

Resection vs thermal ablation of small hepatocellular carcinoma: What's the first choice?

Nowadays, hepatocellular carcinoma (HCC) is frequently diagnosed at an early stage, opening good perspectives to radical treatment by means of liver transplantation, surgical resection, or percutaneous ablation. Liver transplantation is considered the best option, but the lack of liver donors represents a major limitation. Therefore, surgical resection, offering a 5-year-survival rate of over 50%, is considered the first-choice treatment for patients with early stage HCC, whereas percutaneous ablation is usually reserved to patients who are not candidate to surgery. However, in the recent years some trials showed that percutaneous radiofrequency ablation (RFA) can be as effective as surgical resection in terms of overall survival and recurrence-free survival rates in patients with small HCC, and a retrospective comparative study reported 1-, 3-, and 5-year overall survival rates and recurrence-free survival rates significantly better in patients with central HCC measuring 2 cm or smaller treated with RFA than in those treated with surgical resection. RFA is less expensive, less invasive, with lower complication rate and shorter hospital stay than surgical resection, and on the basis of the results of these studies it should be considered the first option in the treatment of very early HCC. However, RFA is size-dependent, so at present the need to achieve an adequate safety margin around the tumor limits to about 2 cm the diameter of the nodules that can be ablated with long-term outcomes comparable to or better than surgical resection. The main goal of the next technical developments of the thermal ablation systems should be the achievement of larger ablation areas with a single needle insertion. In this regard, the recent improvements in microwave energy delivery systems seem to open interesting perspectives to percutaneous microwave ablation, which could become the ablation technique of choice in the next future.

Patterns of recurrence after ablation of colorectal cancer liver metastases

PURPOSE

To determine the local recurrence rate and factors associated with recurrence after intraoperative ablation of colorectal cancer liver metastases.

METHODS

A retrospective analysis of a prospectively maintained database was performed for patients who underwent ablation of a hepatic colorectal cancer metastasis in the operating room from April 1996 to March 2010. Kaplan-Meier survival curves and Cox models were used to determine recurrence rates and assess significance.

RESULTS

Ablation was performed in 10% (n = 158 patients) of all cases during the study period. Seventy-eight percent were performed in conjunction with a liver resection. Of the 315 tumors ablated, most tumors were ≤ 1 cm in maximum diameter (53%). Radiofrequency ablation was used to treat most of the tumors (70%). Thirty-six tumors (11%) had local recurrence as part of their recurrence pattern. Disease recurred in the liver or systemically after 212 tumors (67%) were ablated. On univariate analysis, tumor size greater than 1 cm was associated with a significantly increased risk of local recurrence (hazard ratio 2.3, 95% confidence interval 1.2-4.5, P = 0.013). The 2 year ablation zone recurrence-free survival was 92% for tumors ≤ 1 cm compared to 81% for tumors >1 cm. On multivariate analysis, tumor size of >1 cm, lack of postoperative chemotherapy, and use of cryotherapy were significantly associated with a higher local recurrence rate.

CONCLUSIONS

Intraoperative ablation appears to be highly effective treatment for hepatic colorectal tumors ≤ 1 cm.