Radiofrequency Ablation Safe, Effective in Metastatic Papillary Microcarcinomas of the Thyroid

Radiofrequency ablation was found to be a safe and effective option for treating low-risk metastatic papillary microcarcinomas of the thyroid (PTCs), based on results from a systemic review and meta-analysis published in JAMA Otolaryngology-Head & Neck Surgery.

At the end of a median follow-up of 33.0 months, the complete disappearance rate was 79% (95% CI, 65%-94%). Additionally, the overall tumor progression rate was 1.5% (n = 26) and local residual metastatic PTC in the ablation area was observed in 7 tumors. Additionally, new metastatic PTC in the thyroid was found in 15 patients and 4 patients developed lymph node metastases during follow-up.

A total of 15 studies were eligible to be included this analysis and included in the review, 12 of which were case studies and 3 were retrospective cohorts. Additionally, studies from China or Korea that were published after 2016 were included.

Investigators analyzed 1770 patients, of whom 77.9% were women, with a median age of 45.4 years. A total of 1822 tumors were treated with 1872 radiofrequency ablation sessions. Seven articles were identified that included 1069 patients and focused on exclusion of aggressive histologic variants of metastatic PTC. Overall, 49 tumors received an additional radiofrequency ablative session, and 1 tumor received 2 additional sessions.

Complete disappearance rates were observed on tumor tissue with the use of ultrasonography after radiofrequency ablation. After 12 months, the complete disappearance rate was between 27.8% and 91.0%, and the disappearance rate at the end of follow-up was 29.3% to 100%. At 12 months, the pooled proportion of complete disappearance was 66% (95% CI, 52%-81%).

Investigators identified high heterogeneity between studies at 12 months (I2 = 96.8%; P <.001) and at the end of follow-up (I2 = 99.7%; P <.001).A second ablation instead of follow-up was given to 24 patients across 3 studies who had their metastatic PTC completely ablated without pathologically confirmed metastatic PTC following first ablation. The pooled proportion of tumor progression was 1% (95% CI, 0%-1%), and no evidence of heterogeneity was found (I2 = 4.9%; P = .38). In 25 patients, additional radiofrequency ablative sessions were administered following tumor progression, and 1 patient was given active surveillance.

Of the 15 studies, 9 reported complications which included 2 patients having voice changes that were resolved after 2 months, and 1 report of cardiac arrhythmia during the radiofrequency ablative procedures. It was also noted that 45 minor complications occurred with investigators reporting postoperative pain (n = 20), transient voice changes that resolved within 1 month (n = 14), skin burns (n = 5), hematomas (n = 4), transient hypoparathyroidism (n = 1), and fever (n = 1). The total complication rate was 2% (95% CI, 1%-3%), and there was moderate heterogeneity between studies (I2 = 60.9%; P <.001). The pooled proportion of major complication rate was 0% and there was no heterogeneity between studies (I2, 0.00%; P = .99).

After 12 months, 10 studies reported that the mean tumor volume reduction rate was 92.1% (95% CI, 85.0%-99.2%). Of note, there was high heterogeneity between studies (I2 = 99.8%; P <.001). Volume reduction was observed in 11 studies and was higher than 98.0%.

In 9 studies, most patients had tumor volume increase directly after ablation and then decrease between 1 and 6 months. The pooled proportion of the mean tumor volume was 95.0 mm3 (95% CI, 83.2-106.8), and high heterogeneity between studies (I2 = 87.7%; P <.001). The mean follow-up was 29.8 months.

Reference

van Dijk SPJ, Coerts HI, Gunput STG, et al. Assessment of radiofrequency ablation for papillary microcarcinoma of the thyroid: a systematic review and meta-analysis. JAMA Otolaryngol Head Neck Surg. 2022;148(4):317-325. doi:10.1001/jamaoto.2021.4381