F. Vermiglio et al., Short-term effectiveness of low-dose radioiodine ablative treatment of thyroid remnants after thyroidectomy for differentiated thyroid cancer, THYROID, 9(4), 1999, pp. 387-391
Twenty-five patients from a marginally iodine-deficient area with different
iated thyroid cancer who were referred to our unit between 1991 and 1997 ha
d a residual thyroid uptake (RTU) at 24 hours of 5% or more after surgery.
None of them underwent reoperation: 8 of 25 had RTU between 5% and 10% and
were considered at low risk for both local recurrences and/or distant metas
tases; 17 of 25 had RTU greater than 10% and up to 30% and refused re-inter
vention. After detection of their cervical uptake by using a I-131 tracer d
ose of 3.7 MBq (100 mu Ci), all 25 were treated with 1110 MBq (30 mCi) of I
-131. A whole-body scan (WBS) performed 5 days later revealed I-131 uptake
corresponding to metastatic lymph nodes in the anterior part of the neck in
1 patient and the persistence of only RTU in 24 of 25 patients. RTU and th
yroglobulin (Tg) levels were reevaluated 6 months later in all patients and
compared to preradioiodine treatment values. RTU, ranging at presentation
between 5% and 30%, decreased to below 1% in all but one patient. Serum Tg
values, ranging between 1.6 and 108 ng/mL before radioiodine treatment, dec
reased to below 1.6 ng/mL in all but 4 of them (whose serum Tg was between
2 and 3.4 ng/mL). Our data indicate that 1,110 MBq of I-131 can permit comp
lete ablation of 80% of thyroid remnants concentrating up to 30% of radioio
dine activity. A relation between this high success rate and iodine deficie
ncy can be hypothesized because an increasing uptake of radioiodine by thyr
oid remnants could result in overestimation of their size. Therefore, our o
bservations suggest that in iodine deficient areas, a hasty decision to car
ry out complete thyroidectomy should be avoided, even in the case of thyroi
d remnants with RTU up to 30%.