Thyroid Cancer in Children 101: Is It A Different Animal Than In Adults?
Comments by Dr.G.
1. Thyroid nodules are uncommon in children.
2. However, nodules diagnosed in children carry a greater risk of malignancy compared to those in adults.
2.Children with papillary thyroid cancer are more likely to have regional lymph node involvement, extrathyroidal extension, and pulmonary metastasis.
3. Despite extensive disease at clinical presentation, children are much less likely to die from disease (2% or less long-term cause-specific mortality) than are adults.
4.Many children with pulmonary metastases (30%–45%) develop persistent albeit stable disease following 131I therapy.
5. This is associated with a more favorable progression-free survival in children compared to adults with persistent DTC.
6.There may be a continued clinical response demonstrated by a decline in Tg levels after cessation of RAI therapy in children with pulmonary metastases
7. Compared with adult PTC, childhood PTC is characterized by a higher prevalence of gene rearrangements and a lower frequency of point mutations in the proto-oncogenes implicated in PTC. Recent molecular studies have shown that BRAF mutations are the most common abnormality in adult PTC 36%–83% of cases, but they are rare in children with PTC and virtually absent from the youngest patients.
8. This may be important because point mutations of RAS and BRAF lead to genomic instability and dedifferentiation manifested by decreased expression of the sodium-iodide symporter (NIS).
9. RET/PTC rearrangements are more common in PTC from children and do not lead to genomic instability.
10. These molecular differences might be one of the reasons for better response to RAI therapy in children with PTC and could partially explain their low mortality and rare progression to less-differentiated tumors.
11. A small study of PTC from children and adolescents found distant metastases and recurrence only in tumors with undetectable NIS, and the activity of 131I required to achieve remission was greater in those cancers with undetectable NIS.
12. Molecular differences may have an impact on the utility of molecular testing for diagnosis of thyroid malignancies in children with thyroid nodules.
Children of parents with thyroid cancer need thyroid ultrasound case finding. Familial non-medullary thyroid cancer (FNMPTC)
Children with early Hashimoto’s without hypothyroidism should be treated when the diagnosis is made not when they are finally hypothyroid. Nodules and cancer can be growing during the long latent period before hypothyroidism or nodules and goiter occurs. Earliest thyriid cancer in Hashimoto’s child was 7 years old.
Richard Guttler MD,FACE,ECNU