Indications for Radioactive Iodine Therapy in Papillary Thyroid Carcinoma

High-Risk Disease: RAI Therapy Strongly Recommended

The National Comprehensive Cancer Network recommends radioactive iodine therapy for high-risk papillary thyroid carcinoma features, including gross extrathyroidal extension, distant metastases, tumor >4 cm, or macroscopic lymph node metastases (>5 nodes or any node >3 cm) 1, 2, 3
Gross extrathyroidal extension is an absolute indication for RAI therapy, as recommended by the National Comprehensive Cancer Network and the European Society for Medical Oncology 1, 2
Distant metastases are an absolute indication for RAI therapy, as recommended by the National Comprehensive Cancer Network and the European Society for Medical Oncology 1, 2
Macroscopic lymph node metastases (>5 involved nodes or any node measuring >3 cm) are an absolute indication for RAI therapy, as recommended by the European Society for Medical Oncology 2
Tumor size >4 cm with positive margins is an absolute indication for RAI therapy, as recommended by the National Comprehensive Cancer Network 1, 4
Poorly differentiated histology or aggressive variants (tall cell, columnar cell) are absolute indications for RAI therapy, as recommended by the National Comprehensive Cancer Network 1, 4

The European Society for Medical Oncology recommends considering RAI therapy for intermediate-risk features, including microscopic extrathyroidal extension, vascular invasion, aggressive histology, clinical N1 or pathological N1 disease with ≤5 involved lymph nodes, each <3 cm, multifocal papillary microcarcinoma with extrathyroidal extension and BRAF V600E mutation, and RAI-avid metastatic foci in the neck on post-treatment scan 2, 3
Microscopic extrathyroidal extension is a relative indication for RAI therapy, as recommended by the European Society for Medical Oncology 2
Vascular invasion is a relative indication for RAI therapy, as recommended by the European Society for Medical Oncology 2
Aggressive histology is a relative indication for RAI therapy, as recommended by the National Comprehensive Cancer Network and the European Society for Medical Oncology 1, 2
Clinical N1 or pathological N1 disease with ≤5 involved lymph nodes, each <3 cm, is a relative indication for RAI therapy, as recommended by the European Society for Medical Oncology 2
Multifocal papillary microcarcinoma with extrathyroidal extension and BRAF V600E mutation is a relative indication for RAI therapy, as recommended by the European Society for Medical Oncology 2
RAI-avid metastatic foci in the neck on post-treatment scan is a relative indication for RAI therapy, as recommended by the National Comprehensive Cancer Network 4, 5

The European Society for Medical Oncology recommends avoiding RAI therapy in patients with low-risk criteria, including intrathyroidal tumor ≤1 cm, no locoregional invasion or metastases, clinical N0 or pathological N1 with <5 micrometastases, each <0.2 cm, no distant metastases, no vascular invasion, and non-aggressive histology 2, 3
Intrathyroidal tumor ≤1 cm is a low-risk feature that does not require RAI therapy, as recommended by the European Society for Medical Oncology 2, 3
No locoregional invasion or metastases is a low-risk feature that does not require RAI therapy, as recommended by the European Society for Medical Oncology 2
Clinical N0 or pathological N1 with <5 micrometastases, each <0.2 cm, is a low-risk feature that does not require RAI therapy, as recommended by the European Society for Medical Oncology 2
No distant metastases is a low-risk feature that does not require RAI therapy, as recommended by the European Society for Medical Oncology 2
No vascular invasion is a low-risk feature that does not require RAI therapy, as recommended by the European Society for Medical Oncology 2
Non-aggressive histology is a low-risk feature that does not require RAI therapy, as recommended by the European Society for Medical Oncology 2

The National Comprehensive Cancer Network recommends TSH suppression with levothyroxine to maintain TSH <0.1 mIU/L for high-risk patients 3
The European Society for Medical Oncology recommends TSH maintained at 0.1-0.5 mIU/L for intermediate-risk patients with biochemical incomplete response 3
The European Society for Medical Oncology recommends TSH in low-normal range (0.5-2 mIU/L) for patients with excellent response to treatment 3
The National Comprehensive Cancer Network recommends surveillance thyroglobulin measurements at 6 and 12 months, then annually 4, 5
The European Society for Medical Oncology recommends neck ultrasound for structural disease monitoring 3