Freeze or fry—cryoablation or radiofrequency ablation in liver surgery?

Updates on the Management of Advanced, Metastatic, and Radioiodine Refractory Differentiated Thyroid Cancer

Differentiated thyroid cancer (DTC) accounts for 95% of all thyroid cancers and is generally an indolent tumor, treated effectively with surgery, radioactive iodine, and thyroid-stimulating hormone suppressive therapy. However, 5-10% of patients have advanced disease, with aerodigestive tract invasion, distant metastases, or radioiodine refractory disease, with poor prognosis. This review focuses on the approaches for treating advanced DTC, including management of gross extra-thyroidal extension, recurrent loco-regional or distant metastatic disease, the role of external beam radiation therapy and systemic treatment. Locally ablative treatment modalities, including surgery, radiation therapy, and thermal ablation are evolving and can be used in selected patients. In recent years, new therapeutic agents with molecular targets have become available and two multi-kinase inhibitors, Sorafenib and Lenvatinib, have been licensed for iodine refractory DTC showing an advantage in terms of progression-free survival, although an impact on overall survival has not been proven yet. Management of advanced thyroid cancer can be challenging but a multidisciplinary approach can significantly improve outcomes for this patient population.

Evidence for tumor cell spread during local hepatic ablation of colorectal liver metastases

INTRODUCTION

The aim of the present study was to analyze the impact of cryosurgery (CRYO) on liver metastases compared to other thermoablative techniques. In a rat liver metastases model, evidence for tumor cell spread was analyzed comparing CRYO, radiofrequency ablation (RFA), and laser-induced thermotherapy (LITT).

METHODS

In an experimental study, we compared cell spillage in the washout of isolated perfused rat livers undergoing thermal ablation. Within the same model, CC531-GFP rat liver tumors were treated with CRYO, RFA, or LITT and the number of vital tumor cells within the perfusate was measured. Matrix metalloproteinases (MMP-2, MMP-9) were analyzed after in vivo ablation of rat colorectal liver metastases in the third experimental model.

RESULTS

Our data showed pronounced washout of cells after CRYO with a higher amount of intravascular cells and cell detritus compared to RFA and LITT. Only the effluent fluid of cryosurgery-treated livers revealed GFP-stained tumor cells. MMP-2 and MMP-9 expression was significantly higher after cryosurgery than after RFA and LITT.

CONCLUSION

When using thermoablative techniques, intravascular metastatic cell spillage is highest in CRYO, and increased expression of matrix metalloproteinases may further facilitate tumor cell spread. Therefore, RFA and LITT may be preferable whenever surgical resection of liver tumors is impossible.

Radiofrequency ablation of hepatic metastases from thyroid carcinoma

BACKGROUND

Radiofrequency ablation (RFA) is performed for various types of liver tumors. It might also have a role in the palliative treatment of liver metastases from thyroid carcinoma.

SUMMARY

Three patients with liver metastases of thyroid carcinoma were retrieved from our database of 125 patients who had been treated with RFA for liver tumors. In all three patients, the metastases were a sign of widespread disease, and several other treatment modalities had been performed earlier. Two patients had metastases from medullary thyroid carcinoma and had severe diarrhea. The third patient had a rapidly progressive metastasis of a follicular thyroid carcinoma. The aim of the treatment was cytoreduction with amelioration of symptoms (n = 2) and debulking with increased sensitivity for subsequent (131)I treatment. The ablation was performed via laparotomy (n = 1), laparoscopically (n = 1), or percutaneously (n = 1). One patient experienced superficial burn wounds after a long-lasting RFA procedure. Severity of symptoms was reduced significantly after RFA for a prolonged period of time. RFA induced partial tumor necrosis because of hypervascularization of the tumor in one patient. After arterial embolization the second RFA treatment induced total tumor necrosis. Local recurrences at the site of the ablated liver metastases were not encountered during follow-up.

CONCLUSIONS

RFA is a useful treatment modality in patients with liver metastases from thyroid carcinoma. It should be considered an adjunct to other types of treatment or for those patients in whom more regular treatment modalities are not effective or possible or are associated with increased risks.

Analysis and experimental validation of a triaxial antenna for microwave tumor ablation

We apply a new triaxial antenna for microwave ablation procedures. The antenna consists of a coaxial monopole inserted through an 18-gauge biopsy needle positioned one quarter-wavelength from the antenna base. The biopsy needle creates a triaxial structure, which enhances return loss by more than 10 dB, thus limiting return currents along the feed line. Numerical simulations are used to optimize the antenna design. Numerical and ex-vivo experimental results are presented to quantify the field distribution, heating pattern and return loss of the antenna.