A 45-year-old man undergoes total thyroidectomy for a 4.5 cm follicular thyroid carcinoma with widely invasive histology and 6 foci of vascular invasion. Postoperative radioactive iodine whole body scan shows uptake in the thyroid bed and two pulmonary nodules. What is the TNM stage (AJCC 8th edition) and appropriate RAI dose?

• A Stage I; 30 mCi (1.11 GBq) low-dose RAI
• B Stage II; 100 mCi (3.7 GBq) standard-dose RAI
• C Stage II; 150 mCi (5.55 GBq) high-dose RAI ✓
• D Stage IVB; 150 mCi (5.55 GBq) high-dose RAI

Explanation

Under AJCC 8th edition, any patient aged 55 or younger with distant metastases is Stage II (not Stage IV as in the 7th edition). This 45-year-old man has pulmonary metastases, making him Stage II. Widely invasive follicular carcinoma with distant metastases warrants high-dose RAI (150-200 mCi). Low-dose RAI (30 mCi) is for low-risk ablation. Standard dose (100 mCi) is for intermediate-risk. The presence of distant metastases and widely invasive histology mandates high-dose therapy.

Reference: AJCC Cancer Staging Manual, 8th ed.

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Written and medically reviewed by the StethoPrep medical team.