Low-Dose Radioactive Iodine Ablation Is Sufficient in Patients With Small Papillary Thyroid Cancer Having Minor Extrathyroidal Extension and Central Lymph Node Metastasis (T3 N1a).

PURPOSE: The aim of this study was to evaluate the effectiveness of low-dose radioactive iodine (RAI) ablation in patients with small papillary thyroid cancer (PTC) exhibiting microscopic extrathyroidal extension (mETE) and central lymph node (CLN) metastasis.

METHODS: Among patients who underwent RAI ablation between March 2007 and February 2014, those who had small PTCs (≤2 cm), as well as mETE and CLN metastasis (T3 N1a M0), were enrolled. Response to ablation and long-term outcomes were assessed and compared according to the administered RAI dose. Factors associated with unsuccessful ablation were also determined.

RESULTS: A total of 180 patients were included in the study. Eighty-eight patients had been treated with 1110 MBq (low-dose group) and 92 with 2960 MBq (high-dose group) of RAI. There were no significant differences in the responses to ablation (P = 0.810) and long-term outcomes (P = 0.663) between both groups. Among all patients enrolled, 13 did not achieve successful ablation at long-term follow-up. Logistic regression found that a high ratio of metastatic nodes was a significant factor for predicting unsuccessful ablation.

CONCLUSIONS: Low-dose RAI ablation did not produce significantly different responses or long-term outcomes in patients with small PTCs exhibiting mETE and CLN metastasis. These findings suggest that low-dose ablation may be sufficient in this specific group of intermediate-risk patients, although careful selection is required for patients with a high ratio of metastatic nodes.