CIO 2021-28 Review of Thermal Ablation for Papillary Thyroid Cancer

Purpose: The focus of this educational exhibit is to present a concise review of the utility of thermal ablation in the treatment of papillary thyroid carcinoma (PTC).

Material and Methods: We present a review of the utility of thermal ablation as a treatment for PTC in both text and figure form detailing the supporting data, patient selection, technique.

Results: While there is no clear consensus on the treatment approach for PTC, the initial treatment of choice is surgery. Surgery has a low rate of recurrence, but it is associated with intraoperative injury to the recurrent laryngeal nerve and parathyroid glands. Patients may elect active surveillance (AS) as it as been shown to have an acceptable tumor progression rate. However, AS provides anxiety and concern to patients and physicians alike due to the indwelling cancer. Contrast-enhanced (CE) ultrasound (US) guided thermal ablation, including microwave ablation (MWA) and radiofrequency ablation (RFA) is a treatment modality that has been increasingly studied as it is minimally invasive and effective in treating early-stage (T1a/T1b) PTC. Prior to ablation, a CE US is performed to evaluate tumor enhancement patterns. In the supine position, local anesthesia is administered in the designated ablation site. To reduce injury to adjacent critical structures, a core needle is inserted along the thyroid capsule between the thyroid lobe beside the tumor and adjacent structures for hydrodissection and a distance of at least 5 mm was maintained during ablation. Slow continuous saline infusion may be used to maintain this distance. The power of ablation was maintained at 30-50 W and the ablation was terminated once the hyperechoic ablation zone covered the entirety of the original tumor. CE US is completed to assess ablation effect and determine if further ablation is needed. Data favorably supports the use of thermal ablation in PTC in which >60% of patients experience tumor disappearance. Complications are relatively rare following thermal ablation. Patients with voice hoarseness generally improve within 6 months. Complication rates may be decreased through the use of a high-frequency probe with higher spatial and temporal resolution to guide the ablative procedure and through the use of continuous saline hydrodissection.

Conclusions: Thermal ablation using MWA or RFA under US guidance has been shown to be minimally invasive, safe, and effective in treating early-stage PTC.