What is the standard treatment for thyroid carcinoma?

Standard Treatment for Thyroid Carcinoma

The standard treatment for thyroid carcinoma is total or near-total thyroidectomy followed by risk-stratified radioactive iodine (RAI) therapy, with the specific approach determined by histological subtype and disease stage. 1

Diagnosis and Initial Assessment

• Fine needle aspiration cytology (FNAC) is the first-line diagnostic procedure for thyroid nodules
• Perform FNAC on:
  • Any thyroid nodule >1 cm
  • Nodules <1 cm with suspicious clinical or ultrasonographic features
• Serum calcitonin measurement should be included in the diagnostic evaluation to detect medullary thyroid cancer 2
• Neck ultrasound is essential to assess lymph node status before surgery 2

Treatment Algorithm by Histological Type

Differentiated Thyroid Carcinoma (DTC) - Papillary and Follicular

1. Surgery:

   • Total or near-total thyroidectomy for:
     • Nodules ≥1 cm
     • Any size with metastatic, multifocal, or familial disease 2
   • Less extensive procedures (lobectomy) may be considered for:
     • Unifocal tumors <1 cm (microcarcinomas)
     • Small, intrathyroidal tumors with favorable histology 2
   • Lymph node management:
     • Perform compartment-oriented lymph node dissection for clinically positive nodes
     • Prophylactic central node dissection remains controversial 1

2. Radioactive Iodine (RAI) Therapy:

   • High-risk patients: 100-200 mCi (3.7-7.4 GBq) 2
   • Intermediate-risk patients: 30-100 mCi (1.1-3.7 GBq) 2
   • Low-risk patients: 30 mCi (1.1 GBq) or may omit RAI 2
   • Very low-risk patients (unifocal T1 tumors <1 cm): RAI not indicated 2
   • Preparation via recombinant human TSH (rhTSH) or levothyroxine withdrawal 1

3. Thyroid Hormone Therapy:

   • TSH suppression levels based on risk:
     • High-risk with persistent disease: <0.1 μIU/mL
     • Intermediate/high-risk with incomplete response: 0.1-0.5 μIU/mL
     • Low-risk or excellent response: 0.5-2.0 μIU/mL 1

Medullary Thyroid Cancer (MTC)

1. Surgery:

   • Total thyroidectomy with bilateral prophylactic central lymph node dissection 2
   • Add lateral neck dissection for patients with positive preoperative imaging 2
   • No RAI therapy (MTC cells do not concentrate iodine)

2. Post-surgical Management:

   • Maintain serum TSH within normal range (not suppressed) 1
   • Monitor serum calcitonin and CEA levels 2

Poorly Differentiated and Anaplastic Thyroid Cancer

1. Poorly Differentiated Thyroid Cancer (PDTC):

   • Total thyroidectomy with consideration of lymph node dissection
   • TSH suppressive therapy immediately post-surgery
   • Note: PDTC responds poorly to RAI 2

2. Anaplastic Thyroid Cancer (ATC):

   • Complete resection (R0/R1) when possible
   • High-dose external beam radiotherapy (EBRT) with/without chemotherapy
   • Deliver post-operative radiotherapy as soon as possible 2
   • Multidisciplinary team discussion is essential 2

Management of Recurrent/Metastatic Disease

• Locoregional recurrence: Surgery + RAI when possible 1
• RAI-refractory disease: Consider tyrosine kinase inhibitors:
  • Lenvatinib for locally recurrent or metastatic, progressive, RAI-refractory DTC 3
  • Sorafenib for locally recurrent or metastatic, progressive DTC that is RAI-refractory 4
• Bone metastases: Consider bone resorption inhibitors 1

Follow-up Protocol

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

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

2. Medium-term (6-12 months):

   • Physical examination
   • Neck ultrasound
   • Serum thyroglobulin measurement (basal or stimulated)
   • Consider diagnostic whole-body scan 2, 1

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

   • Physical examination
   • Basal serum thyroglobulin measurement
   • Neck ultrasound 1

Common Pitfalls and Caveats

• Inadequate initial surgery may necessitate more extensive reoperation with higher complication rates 5
• Overtreatment of microcarcinomas (<1 cm) with aggressive surgery when active surveillance may be appropriate 6
• Underestimation of lymph node involvement due to inadequate preoperative imaging
• Inappropriate RAI dosing that doesn't match the patient's risk profile
• Excessive TSH suppression in low-risk patients, increasing risk of cardiac complications and osteoporosis

Despite the increasing incidence of thyroid cancer, mortality rates remain low due to effective treatment strategies and appropriate risk stratification 7, 6.