RESUMEN
PURPOSE: Although minimally invasive follicular thyroid carcinoma (MIFTC) is considered a thyroid tumor with low malignant potential, some MIFTC can spread, metastasize, and eventually lead to death. This study investigates the risk factors for distant metastasis in MIFTC patients. METHODS: Between 1981 and 2014, the records of 365 consecutive patients who underwent thyroidectomy for MIFTC at Seoul National University Hospital were reviewed. Univariate and multivariate analyses were performed to identify risk factors associated with distant metastasis. RESULTS: Of 351 patients, 10 (2.9%) presented with distant metastasis. Of these, two (0.6%) were found at the time of thyroidectomy, while eight (2.3%) were detected at later exams, over a median of 7.3 years (range, 0.2~30.8). In univariate analysis, lymph node metastasis (P<0.001) was significantly associated with distant metastasis. In multivariate analysis, lymph node metastasis (P<0.001) and locoregional recurrence (P=0.008) were significantly associated with distant metastasis. CONCLUSION: Distant metastasis in MIFTC patients were associated with high-risk clinicopathologic features and more aggressive clinical courses. Further study will be needed to ascertain these results with long-term surveillance.