. 2019 Feb;31(1):99–116. doi: 10.21147/j.issn.1000-9604.2019.01.06

2.

Stratification of ongoing assessment of response to therapy

Stratification	Definition (serology and imaging meet simultaneously)		Level I recommendation
Stratification	Serology	Imaging	Level I recommendation
Tg, thyroglobulin; TgAb, thyroglobulin antibody; TSH, thyroid stimulating hormone; FDG, fluorodeoxyglucose. ^a, The risk of recurrence ranged from 1% to 4% over 5−10 years among ER patients. ^b, 15%−20% of IDR patients are reclassified as persistent/recurrent disease over approximately 10 years. ^c, 8%−17% of BIR patients developing structurally identifiable disease over 5−10 years. ^d, Death from disease was seen in 11% of patients with a loco-SIR and in 57% of patients with distant SIR.
Excellent response^a (ER)	Suppressive Tg <0.2 ng/mL or stimulated Tg <1 ng/mL	Negative	Decrease of the intensity and frequency of follow-up and the degree of TSH suppression (1A)
Indeterminate response^b (IDR)	Non-stimulated Tg detectable, but less than 1 ng/mL. Stimulated Tg detectable, but less than 10 ng/mL. Or Tg antibodies stable or declining in the absence of structural or functional disease	Non-specific findings on imaging studies. Or faint uptake in thyroid bed on RAI scanning	Continuing observation with appropriate serial imaging of the nonspecific lesions and serum Tg monitoring. Nonspecific findings that become suspicious over time can be further evaluated with additional imaging or biopsy (1A)
Biochemical incomplete response^c (BIR)	Suppressed Tg >1 ng/mL, Stimulated Tg >10 ng/mL. Or rising TgAb levels	Negative	Those with stable or decreasing serum Tg levels may continue TSH suppression therapy and follow-up; patients with elevated serum Tg or TgAb should prompt additional investigations and potentially additional therapies (1A)
Structural incomplete response^d (SIR)	Serum Tg or TgAb at any level	Structural or functional evidence of disease	Additional treatments or ongoing observation depending on multiple clinicopathologic factors including the size, location, rate of growth, RAI avidity, ¹⁸FDG avidity, and specific pathology of the structural lesions (1A)