Radioiodine can substitute for surgery to
complete thyroidectomy in patients with thyroid cancer
(March 2003)
The background of the study. Some
patients who have a thyroid nodule that proves at surgery to be
a thyroid cancer are advised to have the opposite thyroid lobe removed
because that lobe may contain cancer, and removing it facilitates
the detection of recurrent cancer by radioiodine imaging or measurements
of serum thyroglobulin. This study evaluated the efficacy of radioiodine
(iodine-131) to destroy the opposite lobe of the thyroid in patients
who had undergone thyroid lobectomy.
How the study was done. The study
subjects were 50 adults who had undergone unilateral thyroid lobectomy
for a thyroid nodule that proved to be a papillary or follicular
carcinoma. After an average interval of 14 months (range, 0.25 to
286), the patients were treated with 29.9 mCi (1106 MBq) of iodine-131,
followed by thyroxine therapy. Months later, thyroxine was stopped,
and serum thyrotropin (TSH) and thyroid uptake of iodine-131 were
measured.
The results were compared with the results in a control group of
50 patients who had undergone total or near-total thyroidectomy
for thyroid cancer and had been treated with thyroxine. The thyroxine
was then discontinued, and serum TSH and iodine-131 uptake were
measured later as in the study group.
The results of the study. The mean
serum TSH concentration in the 50 patients in the study group six
months after treatment with iodine-131 was 77 mU/L (range, 12 to
284), and it was 71 mU/L (range, 7 to 184) in the 50 patients in
the control group. Before iodine-131 treatment, the mean 24-hour
thyroid radioiodine uptake in the study group was 19 percent (range,
5 to 36). The mean uptake after iodine-131 treatment was 0.8 percent
(range, 0 to 12). In contrast, the mean iodine-131 uptake in the
control group was 2.4 percent (range, 0 to 10).
The conclusions of the study. A
single dose of iodine-131 is sufficient to destroy the remaining
thyroid lobe in patients who have undergone thyroid lobectomy.
The original article. Randolph GW,
Daniels GH. Radioactive iodine lobe ablation as an alternative to
completion thyroidectomy for follicular carcinoma of the thyroid.
Thyroid 2002;12:989-96.
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