Table 1. Clinical implications of response to therapy reclassification in patients with differentiated thyroid cancer treated with total thyroidectomy and radioiodine remnant ablation.

Binary variable	Category	Definitions	Clinical outcomes
GPG	Excellent response	Negative imaging and either suppressed Tg < 0.2 ng/ml1 or TSH-stimulated Tg < 1 ng/ml1	1–4% recurrence <1% disease-specific death
	Indeterminate response	Non-specific findings on imaging studies Faint uptake in thyroid bed on RAI scanning Non-stimulated Tg detectable, but <1 ng/ml Stimulated Tg detectable, but <10 ng/ml or Anti-Tg antibodies 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
PPG	Biochemical incomplete response	Negative imaging And Suppressed Tg ≥ 1 ng/ml1 Or Stimulated Tg ≥ 10 ng/ml1 Or Rising anti-Tg antibody levels	At least 30% spontaneously evolve to NED 20% achieve NED after additional therapy 20% develop structural disease <1% disease-specific death
	Structural incomplete response	Structural or functional evidence of disease With any Tg level With or without anti-Tg antibodies	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

¹In the absence of anti-Tg antibodies.

Abbreviation: NED, a patient having no evidence of disease at final follow-up.