The Clinical Application of Core-Needle Biopsy after Radiofrequency Ablation for Low-risk Papillary Thyroid Microcarcinoma: A Large Cohort of 202 Patients Study

Purpose: To evaluate the clinical application of core-needle biopsy (CNB) for low-risk papillary thyroid microcarcinoma (PTMC) after radiofrequency ablation (RFA) Methods: A total of 202 patients with 211 low-risk PTMCs were included in this study. RFA procedure was used the hydrodissection technique and moving-shot technique. Patients were followed at 1, 3, 6, 12 months and every 6 months thereafter. The volume of ablation area and the volume reduction ratio (VRR) were calculated. At 3 or 6 months after RFA, CNB was performed to the central zone, the peripheral zone and surrounding thyroid parenchyma for post-ablation evaluation. Results: The mean volume of tumors was 102.34 +/- 93.84 mm(3) (range 4.19-424.10 mm(3)), which decreased significantly to 1.37 +/- 7.74 mm(3) (range 0-73.30 mm(3)) at a mean follow-up time of 24.42 +/- 9.15 months (range 3-42 months) with a mean VRR of 99.14 +/- 4.18% (range 71.88-100%). A total of 3 ablation areas had positive CNB in the peripheral zone and underwent additional RFA. No recurrent or suspicious metastatic lymph nodes were detected Conclusion: CNB is a feasible and effective evaluation for low-risk PTMC after RFA, which can detect residual cancer cells early.