7
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
locoregional
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
growth, RAI avidity,
18
FDG avidity, and
specific patholog y of
the structural lesions.
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 less than 10 ng/mL
OR
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
An indeterminate
response should
lead to continued
observation with
appropriate serial
imaging of the
nonspecific lesions
and serum Tg
monitoring. Non-
specific findings that
become suspicious
over time can be
further evaluated
with additional
imaging or biopsy.
NED denotes a patient as having no evidence of disease at final follow-up.
a
In the absence of Tg antibodies (Tg Ab)
Table 3. Clinical Implications of Response To Therapy
Re-Classification in Differentiated Thyroid Cancer
Patients Treated With Total Thyroidectomy and RAI
Remnant Ablation (cont'd)
Category Definitions Clinical Outcomes
Management
Implications
