What are the guidelines for managing thyroid cancer?

Thyroid Cancer Management Guidelines

Total thyroidectomy followed by risk-stratified radioactive iodine therapy and TSH suppression is the standard management approach for most thyroid cancers, with specific protocols tailored to different histological subtypes. 1

Diagnosis

• Thyroid ultrasound with fine needle aspiration cytology (FNAC) is the first-line diagnostic procedure for thyroid nodules [I, A] 1
• Serum calcitonin measurement should be included in the diagnostic evaluation of thyroid nodules [IV, B] 1
• If FNAC is inadequate, repeat the procedure; for follicular neoplasia with normal TSH and "cold" appearance on scan, consider surgery [IV, B] 1

Management by Thyroid Cancer Type

Differentiated Thyroid Cancer (DTC)

Initial Treatment

1. Surgery

   • Total or near-total thyroidectomy is the standard initial treatment [I, A] 1
   • Less extensive procedures may be acceptable for unifocal tumors that are small, intrathyroidal, and of favorable histology 1
   • Prophylactic central node dissection remains controversial but helps with accurate staging 1

2. Risk Stratification

   • Use established staging systems (AJCC, ATA, ETA) to guide treatment decisions [II, B] 1
   • Risk assessment should be dynamic, with re-stratification based on response to therapy 2

3. Radioactive Iodine (RAI) Therapy

   • High-risk patients: RAI is indicated [IV, B] 1
   • Low-risk patients: RAI is not indicated [IV, D] 1
   • Intermediate-risk patients: Individualize decision based on specific risk factors 1
   • For patients requiring RAI: 30-100 mCi (1.1-3.7 GBq) based on risk factors 1
   • Preparation via rhTSH administration or levothyroxine withdrawal 1

4. Thyroid Hormone Therapy

   • Initiate post-surgery to replace thyroid hormone and suppress TSH 1
   • TSH suppression levels:
     • High-risk patients with persistent disease: <0.1 μIU/mL [III, B] 1
     • Intermediate/high-risk with biochemical incomplete response: 0.1-0.5 μIU/mL [IV, B] 1
     • Low-risk or excellent response: 0.5-2 μIU/mL [IV, B] 1

Follow-up

1. Short-term (2-3 months post-treatment)

   • Thyroid function tests (FT3, FT4, TSH) to assess LT4 therapy adequacy 1

2. Medium-term (6-12 months)

   • Physical examination
   • Neck ultrasound
   • Basal and rhTSH-stimulated serum thyroglobulin with/without diagnostic whole-body scan [I, A] 1
   • High-sensitivity (<0.2 ng/ml) basal Tg assays can replace TSH-stimulated testing [II, B] 1

3. Long-term (annually if disease-free)

   • Physical examination
   • Basal serum Tg measurement on LT4 therapy
   • Neck ultrasound 1

Management of Recurrent/Metastatic Disease

• Locoregional recurrence: Surgery + RAI, supplemented by external beam radiotherapy if surgery is incomplete or RAI uptake is lacking [IV, B] 1
• RAI-refractory disease: Consider lenvatinib or sorafenib [I, A] 1, 3
• Distant metastases: Better outcomes if RAI-avid, small, and located in lungs; otherwise, palliative care 1

Medullary Thyroid Cancer (MTC)

Pre-surgical Workup

• Basal serum calcitonin, CEA, calcium
• Plasma metanephrines/normetanephrines or 24-hour urine collection [IV, A] 1

Treatment

• Without lymph node metastases: Total thyroidectomy with bilateral prophylactic central lymph-node dissection [IV, B] 1
• With positive imaging: Include lateral neck dissection [IV, B] 1
• Post-thyroidectomy, maintain TSH within normal range [IV, B] 1
• Monitor serum markers (calcitonin, CEA) [IV, B] 1
• For advanced disease: Consider vandetanib for locally advanced/metastatic MTC 1

Poorly Differentiated Thyroid Carcinoma (PDTC)

• Total thyroidectomy with consideration of lymph node dissection 1
• TSH suppressive therapy immediately following surgery 1
• Note: PDTC responds poorly to RAI and often requires more aggressive management 1

Anaplastic Thyroid Cancer (ATC)

• Complete or near-complete resection (R0/R1) followed by high-dose EBRT with/without chemotherapy [V, A] 1
• Post-operative radiotherapy should be delivered as soon as possible [IV, A] 1
• Multidisciplinary team discussion is strongly recommended [V, A] 1

Special Considerations

• For bone metastases: Consider bone resorption inhibitors (bisphosphonates, denosumab) [V, B] 1
• Clinical trial enrollment should be encouraged for patients with good performance status [V, B] 1
• BRAF V600E-positive malignancies may benefit from dabrafenib plus trametinib [V, B] 1

Common Pitfalls to Avoid

• Undertreatment of high-risk patients
• Overtreatment of low-risk patients, especially with RAI
• Inadequate TSH suppression in patients with persistent disease
• Failure to re-stratify risk based on response to therapy
• Overlooking the need for completion thyroidectomy in patients initially treated with lobectomy who have pathologic findings requiring RAI 4

The management of thyroid cancer requires a careful balance between effective treatment to reduce mortality and morbidity while avoiding overtreatment that could impact quality of life. Regular monitoring and adjustment of therapy based on disease response is essential for optimal outcomes.