Clinical Significance of Successful Ablation in Follicular Thyroid Carcinoma.

Objective: The purpose of this study is to investigate the clinical characteristics of follicular thyroid carcinoma (FTC) patients who received postoperative ablation, the predictive factors for successful ablation, and the association between successful ablation and the clinical outcomes of FTC.

Patients: The study included 428 patients with FTC (216 in ablation group and 212 in observation group). A multivariate logistic regression model was used to identify factors independently associated with successful ablation.

Results: Patients in the ablation group were significantly older (p < 0.001), had a higher prevalence of widely invasive-FTC histology (p < 0.001), had vascular invasion ≥ 2, and had a higher rate of anti-thyroglobulin antibody positivity (p = 0.007) in comparison to patients in the observation group. Among the 116 patients with postoperative ablation following diagnostic I-131 scintigraphy, 65 (56%) achieved successful ablation. In the multivariate analysis, the thyroglobulin level at ablation as the only independent predictor successful ablation (odds ratio, 0.952; 95% confidence interval, 0.909-0.996; p = 0.034). Among the ablation group, the 10-year cause-specific survival (CSS) rates of patients with (n = 65) and without successful ablation (n = 151) were 100% and 98.4% (p = 0.246), respectively. None of the patients with successful ablation died during the follow-up period. The 10-year distant-metastasis free survival (DMFS) rates of patients with and without successful ablation were 100% and 81.7% (p < 0.001), respectively. None of the patients with successful ablation experienced distant metastatic recurrence during the follow-up period.

Conclusions: FTC patients with successful ablation achieved excellent 10-year CSS and DMFS rates of 100%. Therefore, careful follow-up may be unnecessary for these patients even if they have negative prognostic factors.