Surveillance for DTC

Approach

• Re-stratify patients each review (table under 'adjuvant therapy for DTC')
• Emphasise response to therapy - by using USS and measurements of serum Tg
• 'stimulated Tg' refers to whether or not the patient is having TSH suppression

Response to therapy definitions based on initial therapy

	Initial therapy
	Total thyroidectomy and RAI ablation	Total thyroidectomy without RAI ablation	Lobectomy
Excellent response	Nonstimulated Tg level <0.2 ng/mL* or stimulated Tg level <1 ng/mL* and undetectable TgAb and negative imaging	Nonstimulated Tg level <0.2 ng/mL* or stimulated Tg level <2 ng/mL* and undetectable TgAb and negative imaging	Stable, nonstimulated Tg level <30 ng/mL* and undetectable TgAb and negative imaging
Biochemical incomplete response	Nonstimulated Tg level >1 ng/mL* or stimulated Tg level >10 ng/mL* or increasing TgAb levels and negative imaging	Nonstimulated Tg level >5 ng/mL* or stimulated Tg level >10 ng/mL* or increasing Tg values over time with similar TSH levels or increasing TgAb levels and negative imaging	Nonstimulated Tg level >30 ng/mL* or increasing Tg level values over time with similar TSH levels or increasing TgAb levels and negative imaging
Structural incomplete response	Structural or functional evidence of disease regardless of Tg or TgAb	Structural or functional evidence of disease regardless of Tg or TgAb	Structural or functional evidence of disease regardless of Tg or TgAb
Indeterminate response	Nonspecific findings on imaging studies or faint uptake in thyroid bed on RAI scanning or nonstimulated Tg level 0.2-1 ng/mL* or stimulated Tg level 1-10 ng/mL* or TgAb levels stable or declining in the absence of structural or functional disease	Nonspecific findings on imaging studies or faint uptake in thyroid bed on RAI scanning or nonstimulated Tg level 0.2-5 ng/mL* or stimulated Tg level 2-10 ng/mL* or TgAb levels stable or declining in the absence of structural or functional disease	Nonspecific findings on imaging studies or TgAb levels stable or declining in the absence of structural or functional disease

Differentiated thyroid cancer: Monitoring during the first year after thyroid surgery

	Risk of recurrence
	Low	Intermediate	High
Nonstimulated Tg*	4 to 6 weeks 3 to 6 months 9 to 12 months	4 to 6 weeks 3 to 6 months 9 to 12 months	4 to 6 weeks 3 to 6 months 9 to 12 months
Neck ultrasound	At 6 to 12 months	At 6 to 12 months	Every 6 to 12 months
Diagnostic WBS	Usually not indicated	Case specific	Case specific
MRI, CT	Not indicated	Not indicated	If Tg elevated or high clinical suspicion
FDG-PET	Not indicated	Not indicated	If Tg >10 ng/mL
Serum TSH goal	0.1 to 0.5 mU/L if nonstimulated Tg detectable 0.5 to 2.0 mU/L if nonstimulated Tg undetectable	0.1 to 0.5 mU/L	<0.1 mU/L

Differentiated thyroid cancer: Ongoing monitoring

	Response to therapy
	Excellent	Biochemical incomplete	Structural incomplete	Indeterminate
Nonstimulated Tg	Every one to two years	Every six months	Every six months	6 to 12 months
Stimulated Tg	Not needed	May be repeated at two- to three-year intervals if needed to establish an excellent response to therapy	Not needed	May be repeated at two- to three-year intervals if needed to establish an excellent response to therapy
Neck ultrasound	Consider at three- to five-year intervals	Yearly for five years	Yearly for five years	6- to 12-month intervals for five years
Diagnostic WBS	Not indicated	Not usually done*	To evaluate RAI avidity of structural disease	Not usually done*
MRI, CT	Not indicated	Not indicated*	6- to 12-month intervals depending on rate of progression	Not indicated*
FDG-PET	Not indicated	Not indicated*	To identify additional sites of disease and for prognostic purposes	Not indicated*
Serum TSH¶	0.5 to 2 mU/L	0.1 to 0.5 mU/L	<0.1 mU/L	0.1 to 0.5 mU/L