title: Serum thyrotropin level of 30 μIU/mL is inadequate for preablative thyroglobulin to serve as a prognostic marker for differentiated thyroid cancer.
abstract: OBJECTIVE
  Preablative-stimulated thyroglobulin (ps-Tg) has manifested its potential for predicting prognosis in patients with differentiated thyroid carcinoma (DTC), but its level can be affected by thyrotropin (TSH). The objective of this study was to evaluate the utility of ps-Tg in predicting individual response after radioactive iodine (RAI) therapy, and further explore the appropriate TSH level for ps-Tg to serve as a prognostic marker in DTC without initial distant metastasis (DM).
  
  
  METHODS
  A total of 208 consecutive non-DM DTC patients with serial ps-Tg, TSH, and anti-Tg antibody (TgAb) measured simultaneously were enrolled. The initial and last measurements of ps-Tg were marked as Tg1 and Tg2, respectively, with a median interval of 8 days, so does TSH. Clinical response was retrospectively evaluated as excellent, indeterminate, biochemical incomplete, or structural incomplete response (ER, IDR, BIR, or SIR) after a mean follow-up of 21.5 months. Tg1 and Tg2 were tested and compared for their performances in predicting ER and incomplete response (IR, including BIR and SIR) by receiver operating characteristic (ROC) curve analysis. The 416 ps-Tg levels (Tg1 and Tg2) were then categorized by their corresponding TSH grouping of 30-<60 (n = 100), 60-<90 (n = 131), 90-<120 (n = 99), and ≥120 μIU/mL (n = 86), and the predictive performances were further compared among TSH groups.
  
  
  RESULTS
  Tg2, with a higher corresponding TSH level than Tg1 (median: 104.763 vs. 65.046 μIU/mL), presented higher area under the ROC curve (AUC) in predicting both ER and IR (ER: 0.889 vs. 0.836, P = 0.003; IR: 0.925 vs. 0.869, P = 0.046). The performances of ps-Tg in predicting ER and IR were both improved significantly as TSH rose from 30-<60 to 60-<90 μIU/mL, with an increase in AUC from 0.810 to 0.888 in predicting ER (P = 0.006) and from 0811 to 0.937 in predicting IR (P = 0.014), respectively. However, this kind of benefit was not further enlarged as TSH rose from 60-<90 to 90-<120 μIU/mL (both P > 0.05).
  
  
  CONCLUSIONS
  In comparison with the TSH context of 30 μIU/mL, a higher preablative TSH level of 60-<90 μIU/mL might be more appropriate for ps-Tg to serve as a prognostic marker for DTC.
authors.affiliation: Department of Nuclear Medicine, Peking Union Medical College Hospital, No. 1 Shuaifuyuan, Wangfujing St., Dongcheng District, Beijing, 100730, China.|Department of Oncology, The Affiliated Hospital of Qingdao University, No. 59 Haier St., Laoshan District, Qingdao, 266000, China.
authors.forename: Teng
authors.initials: T
authors.lastname: Zhao
authors.affiliation: Department of Oncology, Peking University International Hospital, No. 1 Life Park St., Zhongguancun Life Science Park, Haidian District, Beijing, 102206, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Liang
authors.affiliation: Department of Medical Records, The Affiliated Hospital of Qingdao University, No. 16 Jiangsu St., Shinan District, Qingdao, 266000, China.
authors.forename: Zhenqing
authors.initials: Z
authors.lastname: Guo
authors.affiliation: Department of Oncology, The Affiliated Hospital of Qingdao University, No. 59 Haier St., Laoshan District, Qingdao, 266000, China.
authors.forename: Jiao
authors.initials: J
authors.lastname: Li
authors.affiliation: Department of Nuclear Medicine, Peking Union Medical College Hospital, No. 1 Shuaifuyuan, Wangfujing St., Dongcheng District, Beijing, 100730, China. linys@pumch.cn.
authors.forename: Yansong
authors.initials: Y
authors.lastname: Lin
mesh_terms: D055011:Ablation Techniques / Q000379:methods*; D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D057234:Preoperative Period; D011379:Prognosis; D012189:Retrospective Studies; D013954:Thyroglobulin / Q000097:blood*; D013964:Thyroid Neoplasms / Q000097:blood* / Q000473:pathology / Q000601:surgery; D013972:Thyrotropin / Q000097:blood*; D016896:Treatment Outcome
chemical_list: D013972:Thyrotropin; D013954:Thyroglobulin
keywords: Differentiated thyroid cancer; Radioactive iodine therapy; Thyroglobulin; Thyrotropin