Clinical Report: Determining a Safe Thermal Ablation Margin for Follicular Adenoma

Overview

This study quantifies the microscopic extent of follicular carcinoma invasion to propose a safe thermal ablation margin for follicular adenoma. The findings suggest an extended ablation margin of 2mm beyond the sonographic tumor boundary to effectively cover occult minimally invasive follicular carcinoma.

Background

Differentiating between follicular adenoma and follicular carcinoma is challenging prior to surgery, which raises concerns about the potential for thermal ablation to treat undetected malignancies. Accurate assessment of the invasion depth in follicular carcinoma is critical for establishing safe ablation margins. This study aims to address these concerns by measuring the infiltration distances in follicular carcinoma.

Data Highlights

Key Findings

• The capsule infiltration distance ranged from 0.14 to 6.10 mm, with a mean of 1.49 ± 1.22 mm.
• The minimally invasive infiltration distance ranged from 0.09 to 1.36 mm, with a mean of 0.56 ± 0.37 mm.
• Infiltration distances did not differ significantly by tumor stage, pathological classification, sex, or lymph node metastasis.
• Age was associated with a larger capsule infiltration distance (P = 0.040).
• The study supports an extended ablation safety margin of 2mm beyond the sonographic tumor boundary.

Clinical Implications

Clinicians should consider the proposed 2mm ablation margin when performing thermal ablation for follicular adenoma to mitigate the risk of inadvertently treating an occult follicular carcinoma. This margin accounts for the potential microscopic invasion that may not be detectable via imaging techniques.

Conclusion

The study provides critical insights into the safe thermal ablation margin for follicular adenoma, emphasizing the need for careful consideration of invasion depth in follicular carcinoma. Implementing the recommended margin may enhance treatment safety and efficacy.

Related Resources & Content

1. Catherine F. Sinclair et al., General Principles for the Safe Performance, Training, and Adoption of Ablation Techniques for Benign Thyroid Nodules: An American Thyroid Association Statement, 2023
2. Five-year follow-up results of thermal ablation for benign thyroid nodules: Systematic review and meta-analysis, PubMed
3. The relationship between ablation range and ablation energy in papillary thyroid microcarcinoma: a comparison between microwave ablation and laser ablation, PubMed
4. European Radiology — Examining the Correlation Between Ablation Energy and Range in Papillary Thyroid Microcarcinoma: A Comparative Study of Microwave and Laser Ablation Techniques
5. The ASCO Post — Margins for Breast-Conserving Surgery With Whole-Breast Irradiation in Ductal Carcinoma in Situ
6. European Radiology — Evaluation of Ablative Margins Following Thermal Ablation of Colorectal Liver Metastases: A Multicenter and Inter-Software Study
7. The ASCO Post — SSO-ASTRO Consensus Guideline on Margins for Breast-Conserving Surgery in Stage I/II Invasive Breast Cancer
8. Examining the Correlation Between Ablation Energy and Range in Papillary Thyroid Microcarcinoma
9. Margins for Breast-Conserving Surgery With Whole-Breast Irradiation in Ductal Carcinoma in Situ
10. Evaluation of Ablative Margins Following Thermal Ablation of Colorectal Liver Metastases
11. General Principles for the Safe Performance, Training, and Adoption of Ablation Techniques for Benign Thyroid Nodules: An American Thyroid Association Statement - Catherine F. Sinclair, Jung Hwan Baek, Kathleen E. Hands, Steven P. Hodak, Timothy C. Huber, Iram Hussain, Brian Hung-Hin Lang, Julia E. Noel, Maria Papaleontiou, Kepal N. Patel, Gilles Russ, Jonathon Russell, Stefano Spiezia, Jennifer H. Kuo, 2023
12. Five-year follow-up results of thermal ablation for benign thyroid nodules: Systematic review and meta-analysis - PubMed
13. The relationship between ablation range and ablation energy in papillary thyroid microcarcinoma: a comparison between microwave ablation and laser ablation - PubMed