Unusual Cancers of Childhood Treatment (PDQ®): Treatment - Health Professional Information [NCI] - Head and Neck Cancers
Table 2. Thyroid Carcinomas in Children continued...
Recurrent papillary thyroid cancer is usually responsive to treatment with radioactive iodine ablation. Tyrosine kinase inhibitors such as sorafenib have shown to induce responses in up to 15% of adult patients with metastatic disease. Responses to sorafenib have also been documented in pediatric cases. Given the high incidence of BRAF mutations in older patients with papillary thyroid carcinoma, the use of selective RAF/MEK inhibitors is being investigated.[78,90,91]
Treatment of medullary thyroid carcinoma
Medullary thyroid carcinomas are commonly associated with the MEN2 syndrome (refer to the Multiple Endocrine Neoplasia (MEN) Syndromes and Carney Complex section of this summary for more information). They present with a more aggressive clinical course; 50% of the cases have hematogenous metastases at diagnosis. Patients with medullary carcinoma of the thyroid have a guarded prognosis, unless they have very small tumors (microcarcinoma, defined as <1.0 cm in diameter), which carry a good prognosis.
Treatment for children with medullary thyroid carcinoma is mainly surgical. A recent review of 430 patients aged 0 to 21 years with medullary thyroid cancer reported older age (16–21 years) at diagnosis, tumor diameter greater than 2 cm, positive margins after total thyroidectomy, and lymph node metastases were associated with a worse prognosis. This suggests that central neck node dissection and dissection of nearby positive nodes should improve the 10-year survival for these patients. Most cases of medullary thyroid carcinoma occur in the context of the MEN 2A and MEN 2B syndromes. In those familial cases, early genetic testing and counseling is indicated, and prophylactic surgery is recommended in children with the RET germline mutation. Strong genotype-phenotype correlations have facilitated the development of guidelines for intervention, including screening and age at which prophylactic thyroidectomy should occur. A natural history study of children and young adults with medullary thyroid cancer is being conducted by the National Cancer Institute (NCT01660984).
A number of tyrosine kinase inhibitors have been evaluated for patients with unresectable medullary thyroid cancer. Vandetanib (an inhibitor of RET kinase, vascular endothelial growth factor receptor, and epidermal growth factor receptor signaling) is FDA-approved for the treatment of symptomatic or progressive medullary thyroid cancer in adult patients with unresectable, locally advanced, or metastatic disease. Approval was based on a randomized, placebo-controlled, phase III trial that showed a marked progression-free survival improvement for patients randomly assigned to receive vandetanib (hazard ratio, 0.35); the trial also showed an objective response rate advantage for patients receiving vandetanib (44% vs. 1% for the placebo arm).[95,96] A phase I trial of vandetanib for children has been completed. Cabozantinib (an inhibitor of the RET and MET kinases and vascular endothelial growth factor receptor) has also shown activity against unresectable medullary thyroid cancer (10 of 35 patients [29%] had a partial response).