Table 2. Thyroid Carcinomas in Children continued...
However, for patients with a small (<1 cm) unifocal nodule, treatment may involve only a lobectomy.[51,58,70]
The use of radioactive iodine ablation for the treatment of children with differentiated thyroid carcinoma has increased over the years. Despite surgery, most children have a significant radioactive iodine uptake in the thyroid bed, and studies have shown increased local recurrence rates for patients who did not receive radioactive iodine after total thyroidectomy compared with those who did receive radioactive iodine. Thus, it is currently recommended that children receive an ablative dose after initial surgery.[46,51,56] For successful remnant ablation, serum TSH levels must be elevated to allow for maximal radioactive iodine uptake; this can usually be achieved with thyroid hormone withdrawal for 3 to 4 weeks after thyroidectomy. A radioactive iodine (I-131) scan is then performed to search for residual, functionally active neoplasm. If there is no disease outside of the thyroid bed, an ablative dose of I-131 (approximately 30 mCi) is administered for total thyroid destruction. If there is evidence of nodal or disseminated disease, higher doses (100–200 mCi) of I-131 are required.[Level of evidence: 3iDiv] In younger children, the I-131 dose may be adjusted for weight (1–1.5 mCi/kg).[46,73,74] After surgery and radioactive iodine therapy, hormone replacement therapy must be given to compensate for the lost thyroid hormone and to suppress TSH production.
Initial treatment (defined as surgery plus one radioactive iodine ablation plus thyroid replacement) is effective in inducing remission for 70% of patients. Extensive disease at diagnosis and larger tumor size predict failure to remit. With additional treatment, 89% of patients achieve remission.
Periodic evaluations are required to determine whether there is metastatic disease involving the lungs. Lifelong follow-up is necessary. T4 and TSH levels should be evaluated periodically to determine whether replacement hormone is appropriately dosed. If thyroglobulin levels rise above postthyroidectomy baseline levels, recurrence of the disease is possible, and physical examination and imaging studies should be repeated. The use of various tyrosine kinase inhibitors or vascular endothelial growth factor receptor inhibitors has shown promising results in patients with metastatic or recurrent thyroid cancer in adults.[78,79,80,81]
Treatment of recurrent papillary and follicular thyroid carcinoma
Patients with differentiated thyroid cancer generally have an excellent survival with relatively few side effects.[77,82,83] Recurrence is common (35%–45%), however, and is seen more often in children younger than 10 years and in those with palpable cervical lymph nodes at diagnosis.[48,84,85] Even patients with a tumor that has spread to the lungs may expect to have no decrease in life span after appropriate treatment. Of note, the sodium-iodide symporter (a membrane-bound glycoprotein cotransporter), essential for uptake of iodide and thyroid hormone synthesis, is expressed in 35% to 45% of thyroid cancers in children and adolescents. Patients with expression of the sodium-iodide symporter have a lower risk of recurrence.