B. De Keizer et al., Efficacy of high therapeutic doses of iodine-131 in patients with differentiated thyroid cancer and detectable serum thyroglobulin, EUR J NUCL, 28(2), 2001, pp. 198-202
Citations number
23
Categorie Soggetti
Radiology ,Nuclear Medicine & Imaging","Medical Research Diagnosis & Treatment
Serum thyroglobulin (Tg) is usually the best marker of residual or metastat
ic disease after treatment of differentiated thyroid cancer. We evaluated t
he effect of so-called blind therapeutic doses of iodine-131 in patients wi
th detectable Tg during suppressive levothyroxine treatment (Tg-on), and in
patients with a negative diagnostic scintigram but detectable Tg during th
e hypothyroid phase (Tg-off). Twenty-two patients with differentiated thyro
id carcinoma underwent total thyroidectomy and radioiodine ablation. During
the follow-up, six patients with detectable Tg-on and 16 patients with det
ectable Tg-off were identified. All patients were treated with a blind ther
apeutic dose of 7,400 MBq iodine-131. Diagnostic scintigrams were compared
with post-treatment scintigrams. Tg-off was measured in 16 cases, 1 year af
ter the administration of the blind therapeutic dose, at the time of the fo
llow-up diagnostic scintigram. Six patients were followed up by Tg-on only.
Post-therapy scintigrams revealed previously undiagnosed local recurrence
or distant metastases in 13/22 cases (59%); the remaining nine post-therapy
scintigrams were negative. At the time of the blind therapeutic doses, Tg-
off values ranged from 8 to 608 mug/l. After 1 year of followup, Tg-off dec
reased in 14/16 (88%) patients. In all patients who were followed by Tg-on
only (n=6), a decrease in Tg Values was measured. It is concluded that blin
d therapeutic doses resulted in a decrease in Tg levels in the majority of
patients with suspected recurrence or metastases. The post-treatment scinti
grams revealed pathological uptake in 59% of patients.