To assess the effectiveness of low-dose (30 mCi) I-131 ablation therapy for remnant thyroid tissue following total thyroidectomy for differentiated thyroid cancer.

Between March 1995 and December 1997, 48 patients were given ablative doses (30 mCi) of I-131 following total thyroidectomy for differentiated thyroid cancer in the presence of I-131 uptake in remnant thyroid tissue. The effective ablation of remnant thyroid tissue was determined using a subsequent I-131 whole body scan. If any remnant thyroid tissue remained, we repeated the same management protocol at 6-month intervals.

Thirty-eight (79.1%) patients displayed papillary, 8 (16.7%) follicular, 1 (2.1%) medullary and 1 (2.1%) Hurthle cell type cancer. Forty-eight patients underwent total thyroidectomy, 35 cases of which underwent central neck dissection, and 14 cases modified radical neck dissection. Postoperative complication developed in 8 cases, including 4 cases of transient hypoparathyroidism, 1 case of permanent hypoparathyroidism, 2 cases of transient recurrent laryngeal nerve palsy, and 1 case of wound hematoma. There was significant remnant thyroid tissue detected in 46 cases (95.8%) following total thyroidectomy, which were able to be ablated by low dose (30 mCi) I-131. There was no statistical difference between the operative procedures or the numbers of treatment of I-131.

This data suggests that low-dose (30 mCi) I 131 therapy is effective for the ablation of remnant thyroid tissue following total thyroidectomy for differentiated thyroid cancer.