title: Clinical Outcome of Remnant Thyroid Ablation with Low Dose Radioiodine in Korean Patients with Low to Intermediate-risk Thyroid Cancer.
abstract: Radioiodine activity required for remnant thyroid ablation is of great concern, to avoid unnecessary exposure to radiation and minimize adverse effects. We investigated clinical outcomes of remnant thyroid ablation with a low radioiodine activity in Korean patients with low to intermediate-risk thyroid cancer. For remnant thyroid ablation, 176 patients received radioiodine of 1.1 GBq, under a standard thyroid hormone withdrawal and a low iodine diet protocol. Serum levels of thyroid stimulating hormone stimulated thyroglobulin (off-Tg) and thyroglobulin-antibody (Tg-Ab), and a post-therapy whole body scan (RxWBS) were evaluated. Completion of remnant ablation was considered when there was no visible uptake on RxWBS and undetectable off-Tg (<1.0 ng/mL). Various factors including age, off-Tg, and histopathology were analyzed to predict ablation success rates. Of 176 patients, 68.8% (n = 121) who achieved successful remnant ablation were classified into Group A, and the remaining 55 were classified into Group B. Group A presented with significantly lower off-Tg at the first radioiodine administration (pre-ablative Tg) than those of Group B (1.2 ± 2.3 ng/mL vs. 6.2 ± 15.2 ng/mL, P = 0.027). Pre-ablative Tg was the only significant factor related with ablation success rates. Diagnostic performances of pre-ablative Tg < 10.0 ng/mL were sensitivity of 99.1%, specificity of 14.0%, positive predictive value of 71.1%, and negative predictive value of 87.5%, respectively. Single administration of low radioiodine activity could be sufficient for remnant thyroid ablation in patients with low to intermediate-risk thyroid cancer. Pre-ablative Tg with cutoff value of 10.0 ng/mL is a promising factor to predict successful remnant ablation.
authors.affiliation: Department of Nuclear Medicine, Seoul National University College of Medicine, Seoul, Korea. ; Department of Nuclear Medicine, Seoul National University Boramae Medical Center, Seoul, Korea.
authors.forename: Seunggyun
authors.initials: S
authors.lastname: Ha
authors.affiliation: Department of Nuclear Medicine, Seoul National University Boramae Medical Center, Seoul, Korea.
authors.forename: So Won
authors.initials: SW
authors.lastname: Oh
authors.affiliation: Department of Nuclear Medicine, Seoul National University Boramae Medical Center, Seoul, Korea.
authors.forename: Yu Kyeong
authors.initials: YK
authors.lastname: Kim
authors.affiliation: Department of Surgery, Seoul National University Boramae Medical Center, Seoul, Korea.
authors.forename: Do Hoon
authors.initials: do H
authors.lastname: Koo
authors.affiliation: Department of Otolaryngology, Seoul National University Boramae Medical Center, Seoul, Korea.
authors.forename: Young Ho
authors.initials: YH
authors.lastname: Jung
authors.affiliation: Department of Internal Medicine, Seoul National University Boramae Medical Center, Seoul, Korea.
authors.forename: Ka Hee
authors.initials: KH
authors.lastname: Yi
authors.affiliation: Department of Nuclear Medicine, Seoul National University College of Medicine, Seoul, Korea. ; Department of Biomedical Sciences, Cancer Research Institute, Seoul National University College of Medicine, Seoul, Korea. ; Laboratory of Molecular Imaging and Therapy, Cancer Research Institute, Seoul National University College of Medicine, Seoul, Korea. ; Tumor Microenvironment Global Core Research Center, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: June-Key
authors.initials: JK
authors.lastname: Chung
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D056910:Republic of Korea; D013954:Thyroglobulin / Q000097:blood / Q000276:immunology; D013961:Thyroid Gland / Q000473:pathology* / Q000528:radiation effects*; D013964:Thyroid Neoplasms / Q000532:radiotherapy*; D013972:Thyrotropin / Q000097:blood; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D007457:Iodine Radioisotopes; D013972:Thyrotropin; D013954:Thyroglobulin
keywords: Differentiated Thyroid Carcinoma; Radioiodine; Remnant Thyroid Ablation; Thyroglobulin