Thick tumor capsule is a valuable risk factor for distant metastasis in follicular thyroid carcinoma

Objective: While the biological behavior of follicular thyroid carcinoma (FTC) has been studied in great detail using clinical experience, few studies have investigated pre- or intraoperative factors related to the risk of distant metastasis (DM) among patients with FTC. The aim of this study was to analyze the characteristics of FTC with DM. Methods: This study retrospectively investigated 102 patients with FTC who underwent surgery between 1988 and 2013. We compared clinicopathological characteristics between FTC with and without DM. Results: Univariate analysis revealed nodal metastasis (p = 0.045), serum thyroglobulin (Tg) at initial operation (>= 1000 ng/ml; p < 0.0001), widely invasive appearance according to macroscopic findings (p < 0.0001), thick tumor capsule (>= 1 mm; p < 0.0001), vascular invasion (p = 0.0003). extrathyroidal invasion (p = 0.047), and venous tumor embolism (p = 0.045) as significant risk factors for DM. Multivariate analysis conducted using pre- and intraoperative factors identified thick tumor capsule (>= 1 mm), serum Tg at initial operation (>= 1000 ng/ml), and macroscopically widely invasive appearance as risk factors independently associated with development of DM. Conclusion: Patients with these risk factors should undergo total thyroidectomy and radioactive iodine ablation. (C) 2017 Elsevier B.V. All rights reserved.