Clinical Outcome of Remnant Thyroid Ablation with Low Dose Radioiodine in Korean Patients with Low to Intermediate-risk Thyroid Cancer.
10.3346/jkms.2015.30.7.876
- Author:
Seunggyun HA
1
;
So Won OH
;
Yu Kyeong KIM
;
Do Hoon KOO
;
Young Ho JUNG
;
Ka Hee YI
;
June Key CHUNG
Author Information
1. Department of Nuclear Medicine, Seoul National University College of Medicine, Seoul, Korea.
- Publication Type:Original Article ; Research Support, Non-U.S. Gov't
- Keywords:
Remnant Thyroid Ablation;
Radioiodine;
Differentiated Thyroid Carcinoma;
Thyroglobulin
- MeSH:
Adolescent;
Adult;
Aged;
Female;
Humans;
Iodine Radioisotopes/*therapeutic use;
Male;
Middle Aged;
Republic of Korea;
Thyroglobulin/blood/immunology;
Thyroid Gland/*pathology/*radiation effects;
Thyroid Neoplasms/*radiotherapy;
Thyrotropin/blood;
Treatment Outcome;
Young Adult
- From:Journal of Korean Medical Science
2015;30(7):876-881
- CountryRepublic of Korea
- Language:English
-
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.
