Thyroid Research Thyroid Research Archive Thyroid Cancer

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.