Dr.Guttler’s Patient Thyroid Blog Post: Radiofrequency Ablation for Thyroid Papillary Microcarcinoma

Review of: van Dijk SPJ, Coerts HI, Gunput STG, van Velsen EFS, Medici M, Moelker A, Peeters RP, Verhoef C, van Ginhoven TM 2022 Assessment of radiofrequency ablation for papillary microcarcinoma of the thyroid: A systematic review and meta-analysis. JAMA Otolaryngol Head Neck Surg. Epub 2022 Feb 10. PMID: 35142816.

SUMMARY

Background

Thyroid cancer is projected to be the fourth-leading cancer diagnosis by 2030 (1). The rise in thyroid cancer is likely due to the increased opportunities for detection and management of subclinical disease, including papillary thyroid microcarcinomas (mPTCs), defined as neoplasms measuring 10 mm or less (2,3). Surgery has historically been the therapy of choice, but there are compelling studies reporting excellent oncologic outcomes for surgical alternatives, including active surveillance and thermal ablation. Avoiding surgery can potentially reduce complications such as recurrent laryngeal-nerve injury and harm from overtreatment. Radiofrequency ablation (RFA) is a nonsurgical, minimally invasive technique that uses alternating electromagnetic current to generate molecular frictional heat to destroy cancer cells. Currently, the literature lacks large-scale studies studying the effectiveness of RFA in mPTCs. The primary goal of this article was to analyze the effectiveness and safety of RFA for low-risk mPTC (4).

Methods

This meta-analysis included studies with adult patients diagnosed with mPTC treated with RFA. Exclusion criteria included articles with patients with preablation lymph node or distant metastasis, recurrence of disease, or extrathyroidal extension. The meta-analysis was conducted in accordance with the Meta-analysis of Observational Studies in Epidemiology (MOOSE) guidelines.

Results

A total of 1770 patients from 15 studies were included in the meta-analysis. All studies took place in Asia, including 11 from China and 4 from South Korea. A total of 79% of patients with mPTC who underwent RFA had complete disappearance of tumor tissue on ultrasonography (95% CI, 65–94). Twenty-two patients (1.2%) had FNA-confirmed residual mPTC or a new mPTC. Overall tumor progression was found in 26 patients (1.5%), local residual mPTC in the ablation area was found in 7 tumors (0.4%), new mPTC was found in 15 patients (0.9%), and 4 patients (0.2%) developed lymph node metastases on follow-up. The mean follow-up time was 33 months (range, 6–131). All residual tumors were removed by additional RFA. No patients developed distant metastases. Major complications (defined as temporary voice changes and temporary cardiac arrhythmias during RFA) occurred in 0.17% of patients. All major and minor complications spontaneously resolved within 3 months after RFA treatment.

Conclusions

This study supports that RFA is a potentially safe and efficient tool to treat low-risk mPTCs. Complication rates were low and manageable, typically resolving within 3 months after RFA treatment. Long-term follow-up is needed to determine its oncologic utility in comparison to surgery and active surveillance.

COMMENTARY

In 2015, the American Thyroid Association guidelines incorporated active surveillance as an option for carefully selected patients (5). This study supports RFA as an efficacious option for patients who are unwilling or unable to undergo active surveillance for mPTC. Its utility also includes patients undergoing active surveillance who have local growth or patients with significant comorbidities. RFA as an alternative to surgery may offer benefits that include absence of a scar, elimination of the possibility of hypothyroidism, and a lower risk of complications.

Whether these mPTCs and residual mPTCs are clinically significant is an important topic for discussion. For over 50 years, pathologists have reported papillary thyroid cancer as a common autopsy finding in asymptomatic patients (6–9). Indeed, to date studies of active surveillance have demonstrated that, in most cases, no intervention is ever needed. Although some thyroid cancers can metastasize; confer local symptoms involving speech, airway, and swallowing; and cause death, mPTC has an overall survival rate over 99% (10). For most situations, these cancers have long been recognized to exist in a subclinical form.

The utility of RFA may lie in the middle ground between surgery and active surveillance. It is less invasive than surgery, yet its role in eliminating most cancers may satisfy patients who are too anxious for active surveillance and for clinicians concerned about disease progression or metastasis. For instance, although the incidence of regional metastasis over time in patients under active surveillance is low (11), a commonly voiced concern is that leaving the primary cancer intact may theoretically invite future nodal spread. Current guidelines (12) also support RFA for patients who decline active surveillance or surgery. Nonetheless, RFA has its own concerns: for instance, >20% of cases will have residual nodule tissue that can often be challenging to interpret and follow on ultrasonography. Such ambiguity may further complicate monitoring protocols. It also remains to be seen whether the results from the Chinese and Korean studies in this meta-analysis are reproducible in other countries, which have varying rates of diagnostic workup patterns (13).

Diagnostic techniques such as high-resolution ultrasonography have improved detection of thyroid cancers, many of which are subclinical. In turn, there remains concern that treatment of these mPTCs has negligible impact on outcomes or, worse yet, increases the risk of patient harm. Future studies of RFA should include longer patient follow-up and meticulous reporting of outcomes. Active surveillance and the use of RFA, as supported by this study, have the potential to reshape current treatment for mPTC.

Disclosures: The authors have no conflicts of interest to declare.