Patients with thyroid cancer who have low
serum thyroglobulin concentrations after surgery have a low risk
of tumor recurrence
(July 2005)
The background of the study. High serum thyroglobulin
concentrations indicate the presence of persistent or recurrent
tumor in patients with papillary or follicular carcinoma of the
thyroid. This study was done to determine whether measurements of
serum thyroglobulin at the time of initial radioactive iodine (I-131)
therapy predict recurrence in patients with these tumors.
How the study was done. The study subjects were
268 patients with thyroid carcinoma localized to the neck at the
time of initial surgery and I-131 therapy. Serum thyroglobulin was
measured five to six weeks after surgery, during which time no thyroid
hormone had been given and hypothyroidism developed. The patients
were given I-131 to destroy any remaining thyroid tissue and then
given thyroid hormone. Subsequently, the patients were evaluated
for tumor recurrence at 6- to 12-month intervals.
The results of the study. At the time of I-131
therapy, 64 of the 268 patients (24 percent) had a serum thyroglobulin
value >10 ng/ml, of whom 27 (42 percent) had a recurrence during
follow-up. The serum thyroglobulin value was >2 to 10 ng/ml in
79 patients, of whom 6 (8 percent) had a recurrence, and the value
was ≤2 ng/ml in 125 patients, of whom 2 (2 percent) had a
recurrence.
The conclusions of the study. Patients with thyroid
carcinoma who have a low serum thyroglobulin concentration when
hypothyroidism is present at the time of I-131 therapy after surgery
are unlikely to have a recurrence of their tumor.
The original article. Kim TY, Kim WB, Kim ES,
Ryu JS, Yeo JS, Kim SC, Hong SJ, Shong YK. Serum thyroglobulin levels
at the time of 131I remnant ablation just after thyroidectomy are
useful for early prediction of clinical recurrence in low-risk patients
with differentiated thyroid carcinoma. J Clin Endocrinol Metab 2005;90:1440-5.
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