Is surgery and medication, including levothyroxine (thyroid hormone suppression therapy) and possibly sorafenib (tyrosine kinase inhibitor) or lenvatinib (tyrosine kinase inhibitor), medically indicated for a patient with thyroid carcinoma who has a new growth on the right thyroid gland and is status post (s/p) left-sided thyroidectomy?

Surgery and Medication Are Medically Indicated for This Patient

For a patient with thyroid carcinoma who has developed a new growth on the remaining right thyroid lobe after previous left thyroidectomy, completion thyroidectomy is indicated, followed by levothyroxine therapy and consideration of radioactive iodine (RAI) treatment based on final pathology and risk stratification. 1

Surgical Management

Completion thyroidectomy (removal of the remaining right thyroid lobe) is the appropriate surgical intervention for this patient with a new growth on the contralateral thyroid after previous lobectomy. 1

Indications for Surgery:

• New growth on remaining thyroid tissue in a patient with known thyroid carcinoma history warrants total thyroidectomy to enable complete disease staging, facilitate RAI therapy if needed, and allow reliable thyroglobulin monitoring. 1
• The surgery should include central neck dissection (level VI) if lymph node metastases are suspected on preoperative imaging or physical examination. 1
• Lateral neck dissection (levels II-IV) should be performed only if there is evidence of lateral neck lymph node involvement on preoperative ultrasound or other imaging. 1

Preoperative Evaluation:

• Obtain preoperative vocal cord assessment to document baseline laryngeal nerve function, especially important given the previous thyroidectomy. 1
• Perform neck ultrasound to evaluate for lymph node metastases and assess the extent of disease. 1
• Consider CT or MRI for fixed, bulky, or substernal lesions, avoiding iodinated contrast if possible to preserve future RAI treatment options. 1

Medication Management

Levothyroxine (Thyroid Hormone Therapy)

Levothyroxine therapy is mandatory after completion thyroidectomy and serves dual purposes: thyroid hormone replacement and TSH suppression. 1, 2

TSH Suppression Strategy Based on Risk:

• For high-risk patients (extensive disease, metastases, aggressive histology): maintain TSH <0.1 μIU/mL to suppress potential tumor growth stimulus. 1
• For intermediate-risk patients: maintain TSH 0.1-0.5 μIU/mL during initial follow-up period. 1
• For low-risk patients who achieve excellent response to therapy: TSH can be maintained at 0.5-2 μIU/mL (low-normal range). 1, 3
• TSH suppression should be maintained for 3-5 years in high-risk patients even if they appear disease-free after initial treatment, due to significant long-term relapse risk. 1

Administration:

• Administer as a single daily dose on an empty stomach, 30-60 minutes before breakfast with a full glass of water. 2
• Administer at least 4 hours before or after drugs that interfere with absorption (calcium, iron, proton pump inhibitors). 2

Radioactive Iodine (RAI) Therapy

RAI treatment should be considered based on final pathology and risk stratification after completion thyroidectomy. 1

Indications for RAI:

• High-risk features: extrathyroidal extension, lymph node metastases, distant metastases, aggressive histology, or tumor >4 cm. 1
• Intermediate-risk features may warrant RAI remnant ablation to facilitate subsequent thyroglobulin monitoring and disease surveillance. 1
• Low-risk patients with excellent response (thyroglobulin <1 ng/mL, negative imaging) may not require RAI. 1

Tyrosine Kinase Inhibitors (Sorafenib/Lenvatinib)

TKIs are NOT indicated at this stage unless the patient develops RAI-refractory, progressive, metastatic disease. 1, 4

When TKIs Become Appropriate:

• Sorafenib or lenvatinib should only be considered for locally recurrent or metastatic, progressive differentiated thyroid carcinoma that is refractory to RAI treatment. 4
• Lenvatinib demonstrates superior progression-free survival (18.3 months vs 3.6 months placebo) with 64.7% objective response rate in RAI-refractory disease. 5
• In real-world comparative studies, lenvatinib showed longer PFS (35.3 months) compared to sorafenib (13.3 months) as first-line therapy for RAI-refractory disease. 6
• Common grade 3-4 adverse events with lenvatinib include hypertension (16%), proteinuria (32%), and hand-foot skin reaction, requiring close monitoring. 6, 7

Post-Treatment Surveillance

After completion thyroidectomy and any adjuvant RAI therapy, implement risk-stratified surveillance:

For Excellent Response (no evidence of disease):

• Measure serum thyroglobulin and thyroglobulin antibodies every 12-24 months. 1
• Neck ultrasound can be repeated every 12-24 months or deferred if thyroglobulin remains undetectable. 1
• Maintain TSH in low-normal range (0.5-2 μIU/mL) for low-risk patients with excellent response. 1

For Biochemical Incomplete Response (detectable thyroglobulin, negative imaging):

• Measure thyroglobulin every 6-12 months and monitor trends. 1, 3
• Rising thyroglobulin levels (especially doubling time <1 year) are highly suspicious for recurrence and should prompt imaging with neck ultrasound and potentially FDG-PET. 1, 3
• Maintain TSH 0.1-0.5 μIU/mL in this scenario. 1

For Structural Incomplete Response (visible disease on imaging):

• Measure thyroglobulin every 3-6 months. 1
• Perform neck ultrasound and other imaging every 3-6 months to assess disease progression. 1
• Maintain TSH <0.1 μIU/mL to maximally suppress tumor growth. 1

Critical Pitfalls to Avoid

• Do not initiate TKIs for localized disease or as adjuvant therapy – these are reserved exclusively for RAI-refractory, progressive, metastatic disease due to significant toxicity and lack of benefit in earlier stages. 1, 4
• Do not use TSH suppression in medullary thyroid cancer – C cells lack TSH receptors, making suppression ineffective and potentially harmful. 1
• Do not rely on single thyroglobulin measurements – trends over time are more reliable, and rising levels warrant investigation even if absolute values are low. 1, 3
• Ensure adequate TSH stimulation (>30 μIU/mL) before RAI therapy or diagnostic scanning to maximize iodine uptake. 1
• Screen for iodine contamination before RAI therapy – avoid iodinated contrast for at least 6-8 weeks prior. 1