A 55-year-old woman with a 4 cm papillary thyroid carcinoma and no lymph node involvement (T3aN0M0) undergoes total thyroidectomy. She is found to have a germline RET mutation consistent with familial non-medullary thyroid carcinoma. Post-thyroidectomy, which radioactive iodine (RAI) adjuvant therapy approach is recommended by current ATA guidelines for intermediate-risk PTC?

• A RAI is absolutely contraindicated in germline mutation carriers
• B All intermediate-risk PTC requires high-dose RAI (3.7–7.4 GBq; 100–200 mCi)
• C External beam radiotherapy to the neck instead of RAI
• D RAI ablation with low-dose 1.1 GBq (30 mCi) remnant ablation may be considered; high-dose not routinely required ✓

Explanation

ATA 2015 guidelines classify this patient as intermediate risk (T3a = microscopic extra-thyroidal extension or tumour >4 cm). For intermediate-risk PTC, low-dose RAI remnant ablation (1.1 GBq/30 mCi) has equivalent efficacy to high-dose (3.7 GBq/100 mCi) for remnant ablation per the ESTIMABL and HiLo trials. High-dose RAI is reserved for high-risk features (distant metastases, incomplete resection, aggressive histology). Germline mutations in familial PTC are not a contraindication to RAI. External beam radiotherapy is not standard for PTC without unresectable gross residual disease.

Reference: Bailey & Love's Short Practice of Surgery, 27th ed.

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Written and medically reviewed by the StethoPrep medical team.