title: Risk factors of distant metastasis in the follicular variant of papillary thyroid carcinoma.
abstract: OBJECTIVE
  The follicular variant of papillary thyroid carcinoma (FVPTC) is the most common variant of papillary thyroid carcinoma (PTC). A previous population-based study revealed its clinical behavior as a mix of classic papillary thyroid carcinoma (C-PTC) and follicular thyroid carcinoma. Whereas locoregional extension was lower in FVPTC than in C-PTC, the distant metastasis rate was higher in FVPTC than in C-PTC. The aim of this study was to evaluate the risk factors of distant metastasis in FVPTC postoperatively.
  
  
  METHODS
  A retrospective review of 359 patients with final pathological diagnosis of FVPTC treated at Chang Gung Memorial Hospital between January 2000 and January 2014 was performed. After excluding patients who had inadequate pathological data for analysis or did not attend regular follow up for >1 year, 346 patients were included in this study. Univariate and multivariate statistical analyses were performed to determine the significance of various factors.
  
  
  RESULTS
  Of the 346 patients with FVPTC, 19 (5.5%) had lymph node metastases and 32 (9.2%) had distant metastases. Two positive and one negative risk factors were predictive for distant metastasis using multivariate analysis: angiolymphatic invasion [odds ratio (OR), 3.085; 95% confidence interval (CI), 1.008-9.442], extrathyroidal extension (OR, 3.929; 95% CI, 1.330-11.602), and encapsulation (OR, 0.361; 95% CI, 0.154-0.850).
  
  
  CONCLUSIONS
  The presence of angiolymphatic invasion, extrathyroidal extension, or nonencapsulation was associated with distant metastasis in FVPTC in this study. In FVPTC patients, postoperative investigation for distant metastasis may be warranted by the presence of these two positive risk factors or the absence of the one negative risk factor.
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, Chang Gung Memorial Hospital, Chang Gung University College of Medicine Taoyuan City, Taiwan, ROC.
authors.forename: Yan-Rong
authors.initials: YR
authors.lastname: Li
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, Chang Gung Memorial Hospital, Chang Gung University College of Medicine Taoyuan City, Taiwan, ROC. Electronic address: stc1105@cgmh.org.tw.
authors.forename: Szu-Tah
authors.initials: ST
authors.lastname: Chen
authors.affiliation: Department of Pathology, Chang Gung Memorial Hospital, Taoyuan City, Taiwan, ROC.
authors.forename: Chuen
authors.initials: C
authors.lastname: Hseuh
authors.affiliation: Department of General Surgery, Chang Gung Memorial Hospital, Taoyuan City, Taiwan, ROC.
authors.forename: Tzu-Chieh
authors.initials: TC
authors.lastname: Chao
authors.affiliation: Department of Nuclear Medicine and Molecular Imaging Center, Chang Gung Memorial Hospital, Taoyuan City, Taiwan, ROC.
authors.forename: Tsung-Ying
authors.initials: TY
authors.lastname: Ho
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, Chang Gung Memorial Hospital, Chang Gung University College of Medicine Taoyuan City, Taiwan, ROC. Electronic address: einjd@adm.cgmh.org.tw.
authors.forename: Jen-Der
authors.initials: JD
authors.lastname: Lin
mesh_terms: D000328:Adult; D018265:Carcinoma, Papillary, Follicular / Q000473:pathology* / Q000601:surgery; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D016015:Logistic Models; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D011379:Prognosis; D012189:Retrospective Studies; D012307:Risk Factors; D013624:Taiwan; D013954:Thyroglobulin / Q000097:blood; D013961:Thyroid Gland / Q000473:pathology*; D013964:Thyroid Neoplasms / Q000473:pathology* / Q000601:surgery; D013965:Thyroidectomy
chemical_list: D013954:Thyroglobulin
keywords: distant metastasis; follicular variant of papillary thyroid carcinoma; risk factor