ATA Guideline in a View Point of Nuclear Medicine

Ju Won Seok

doi:10.11106/ijt.2015.8.2.129

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Seok: ATA Guideline in a View Point of Nuclear Medicine

Review Article

Int J Thyroidol 2015;8(2):129-136.

Published online: 20 November 2015

DOI: https://doi.org/10.11106/ijt.2015.8.2.129

ATA Guideline in a View Point of Nuclear Medicine

Ju Won Seok

Department of Nuclear Medicine, College of Medicine, Chung-Ang University, Seoul, Korea

Correspondence: Ju Won Seok, MD, PhD, Department of Nuclear Medicine, College of Medicine, Chung-Ang University, 102 Heukseok-ro, Dongjak-gu, Seoul 156-755, Korea Tel: 82-2-6299-2897, Fax: 82-2-6299–2899, E-mail: joneseok@cau.ac.kr

Received 18 March 2015 Revised 18 May 2015 Accepted 15 June 2015

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Since the American Thyroid Associationʼ s guidelines for the management of thyroid nodule and differentiated thyroid cancer were published in 1996 and revised in 2006 and 2009, significant scientific advances have occurred in the field. The new revised guideline for informing clinicians, patients, researchers, and health policy makers on updated published evidence relating to the diagnosis and management of thyroid nodules and differentiated thyroid cancer is recently announced. We reviewed the part which is related the nuclear medical diagnosis and treatment in the new guideline and expected it will be made the new guideline for nuclear medicine physician based on the consensus among nuclear medicine physicians and the verification through further research.

Keywords: Thyroid nodule, Differentiated thyroid cancer, Guideline, Nuclear medicine

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Table 1.

Clinical implications of response to therapy re-classification in differentiated thyroid cancer patients treated with total thyroidectomy and RAI remnant ablation

Category	Definitions	Clinical outcomes	Management implications
Excellent response	Negative imaging and either Suppressed Tg＜0.2 ng/mL∗ or TSH stimulated Tg＜1 ng/mL∗	1–4% recurrence ＜1% disease specific death	An excellent response to therapy should lead to an early decrease in the intensity and frequency of follow up and the degree of TSH suppression
Biochemical incomplete response	Negative imaging and Suppressed Tg＞1 ng/mL∗ or Stimulated Tg＞10 ng/mL∗ or Rising anti-Tg Ab levels	At least 30% spontaneously evolve to NED 20% achieve NED after additional therapy 20% develop structural disease ＜1% disease specific death	If associated with stable or declining serum Tg values, a biochemical incomplete response should lead to continued observation with ongoing TSH suppression in most patients.
Biochemical incomplete response			Rising Tg or Tg antibody values should prompt additional investigations and potentially additional therapies.
Structural incomplete response	Structural or functional evidence of disease With any Tg level +/- Tg Ab	50–85% continue to have persistent disease despite additional therapy Disease specific death rates as high as 11% with loco-regional metastases and 50% with structural distant metastases	A structural incomplete response may lead to additional treatments or ongoing observation depending on multiple clinico-pathologic factors including the size, location, rate of gro-wth, RAI avidity, FDG avidity, and specific pathology of the structural lesions.
Structural incomplete response		Disease specific death rates as high as 11% with loco-regional metastases and 50% with structural distant metastases
Indeterminate response	Non-specific findings on imaging studies Faint uptake in thyroid bed on RAI scanning Non-stimulated Tg detectable, but less than 1 ng/mL Stimulated Tg detectable, but less than 10 ng/mL or Tgantibodies stable or declining in the absence of structural or functional disease	15–20% will have structural disease identified during follow-up In the remainder, the non-specific changes are either stable, or resolve ＜1% disease specific death	An indeterminate response should lead to continued observation with appropriate serial imaging of the non-specific lesions and serum Tg monitoring. Non-specific findings that become suspicious over time can be further evaluated with additional imaging or biopsy.
	Non-stimulated Tg detectable, but less than 1 ng/mL	In the remainder, the non-specific changes are either stable, or resolve ＜1% disease specific death
	Stimulated Tg detectable, but less than 10 ng/mL or Tgantibodies stable or declining in the absence of structural or functional disease

^∗ In the absence of anti-Tg antibodies

FDG: flourodeoxyglucose, RAI: radioactive Iodine, Tg: thyroglobulin, Tg Ab: thyroglobulin antibody, TSH: thyroid stimulating hormone

Table 2.

Characteristics according to the ATA risk stratification system and AJCC/TNM staging system that may impact post-operative RAI decision-making

ATA recurrence risk Staging T N M	Description	Body of evidence suggests RAI improves disease-specific survival?	Body of evidence suggests RAI improves disease-free survival?	Post-surgical RAI indicated?
ATA low risk T1a N0, Nx M0, Mx	Tumor size ≤1 cm (uni-or multi-focal)	No	No	No
ATA low risk T1b, T2 N0, Nx M0, Mx	Tumor size ＞1–4 cm	No	Conflicting observational data	Not routine – May be considered for patients with aggressive histology or vascular invasion (ATA intermediate risk)
ATA low to intermediate risk T3 N0, Nx M0, Mx	Tumor size ＞4 cm	Conflicting data	Conflicting observational data	Consider – Need to consider presence of other adverse features. Advancing age may favor RAI use in some cases, but specific age and tumor size cut-offs subject to some uncertainty
ATA low to intermediate risk T3 N0, Nx M0, Mx	Microscopic extra-thyro-idal extension, any tu-mor size	No	Conflicting observational data	Consider – Generally favored based on risk of recurrent disease. Smaller tumors with microscopic ETE may not require RAI
ATA low to intermediate risk T1–3 N1a M0, Mx	Central compartment ne-ck lymph node meta-stases	No, except possibly in subgroup of patients ≥45 years of age (NTCTCSG stage III)	Conflicting observational data	Consider – Generally favored, due to somewhat higher risk of persistent or recurrent disease, especially with increasing number of large (＞2–3 cm) or clinically evident lymph nodes or presence of extra-nodal extension. Advancing age may also favor RAI use. However, there is insufficient data to mandate RAI use in patients with few (＜5) microscopic nodal metastases in central compartment in absence of other adverse features.
ATA low to intermediate risk T1–3 N1b M0, Mx	Lateral neck or medias-tinal lymph node me-tastases	No, except possibly in subgroup of patients ≥45 years of age	Conflicting observational data	Consider – Generally favored, due to higher risk of persistent or recurrent disease, especially with increasing number of macroscopic or clinically evident lymph nodes or presence of extra-nodal extension. Advancing age may also favor RAI use
ATA high risk T4 Any N Any M	Any size, gross extra- thyroidal extension	Yes (observational data)	Yes (observational data for disease persistence and recurrence)	Yes
ATA high risk M1 Any T Any N	Distant metastases	Yes (observational data)	Yes (observational data)	Yes

AJCC: American Joint Committee on Cancer, ATA: American Thyroid Association, NTCTCSG: National Thyroid Cancer Treatment Cooperative Study Group, RAI: radioactive Iodine, TNM: tumor node metastasis

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