Risk of recurrence in patients with papillary thyroid carcinoma and minimal extrathyroidal extension not treated with radioiodine.

Purpose: This study evaluated the recurrence rate in patients with papillary thyroid carcinoma (PTC) and minimal extrathyroidal extension (mETE) who had low thyroglobulin (Tg) after total thyroidectomy, and therefore, did not receive radioactive iodine (RAI).
Methods: This was a prospective study including 182 patients with tumors ≤ 4 cm and mETE without aggressive histology or clinically apparent lymph node involvement (cN0pNx). After thyroidectomy, all patients had nonstimulated Tg ≤ 0.3 ng/ml, negative antithyroglobulin antibodies (TgAb), and neck ultrasonography (US) showing no anomalies. Because of these results, the patients were not submitted to RAI.
Results: The time of follow-up ranged from 24 to 132 months (median 72 months). One hundred and seventy-eight patients (97.8%) continued to have nonstimulated Tg ≤ 0.3 ng/ml and negative US. Four patients (2.2%) exhibited an increase in Tg and lymph node metastases (structural recurrence). After surgery, these patients obtained nonstimulated Tg < 1 ng/ml and no apparent tumor was detected by the imaging methods.
Conclusion: The results suggest that patients with mETE and without other adverse features, who have low nonstimulated Tg and negative neck US after thyroidectomy, do not require ablation with RAI.