Head and Neck Cancers
The management of differentiated thyroid cancer in children has been reviewed in detail.
Surgery by an experienced thyroid surgeon is the treatment required for all thyroid neoplasms. For patients with papillary or follicular carcinoma, total or near-total thyroidectomy plus cervical lymph node dissection, when indicated, is the most common surgical approach.[44,62] For patients with obvious metastatic disease or heavy nodal invasion, total thyroidectomy and treatment with radioactive iodine is indicated. For patients with a small (<1 cm) unifocal nodule, treatment may involve only a lobectomy.[42,44,63] During the 4- to 6-week period following surgery, patients who undergo total or near-total thyroidectomy will develop hypothyroidism. 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 to 200 mCi) of I-131 are required. In children, the I-131 dose may be adjusted for weight and other age-dependent safety factors.[64,65] After surgery and radioactive iodine therapy, hormone replacement therapy must be given to compensate for the lost thyroid hormone and to suppress thyrotropin (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.[69,70,71,72]
Patients with differentiated thyroid cancer generally have an excellent survival with relatively few side effects.[68,73,74] 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.[39,75,76] Recurrent papillary thyroid cancer is usually responsive to treatment with radioactive iodine ablation. 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. (Refer to the PDQ summary on adult Thyroid Cancer Treatment for more information.)