medwireNews: Children younger than 12 years should be carefully monitored after undergoing surgery for differentiated thyroid carcinoma (DTC) because of a high risk of residual or recurrent disease, study results indicate.

Researchers retrospectively assessed the outcomes of 62 patients with DTC, of whom 22 were younger than 12 years at diagnosis and 40 were aged between 13 and 18 years.

After surgical treatment, 41% of the younger age group had residual disease, compared with just 15% of the teenagers. Furthermore, 27% of the younger patients developed recurrent disease versus just 5% of the older group, equating to 50% versus 6% of those who had undetectable disease after surgery.

This was despite the two age groups having otherwise similar baseline characteristics and receiving comparable treatment, with around two-thirds undergoing primary total thyroidectomy, and also receiving equivalent initial radiation doses.

The researchers note that cumulative radiation dose was higher in the younger children, consistent with them receiving “more aggressive post-surgical treatment, reflecting the higher rates of residual and recurrent disease in this age group.”

The only other differences between the younger versus the older patients were a nonsignificant trend towards more pulmonary metastases, at 32% versus 12%, and a significantly higher rate of metastases in those who underwent lateral neck dissection (around a quarter of all DTC patients), at 64% versus 48%.

“Thus, it is possible that the intrinsic biology of paediatric thyroid cancer differs between children and adolescents”, write Jonathan Wasserman (The Hospital for Sick Children, Toronto, Ontario, Canada) and study co-authors in Clinical Endocrinology.

However, they say that there could be other explanations; for example, “a greater burden of recurrent disease in younger patients may reflect less aggressive neck dissection at the time of initial surgery, in an effort to limit the rate of surgical complications.”

They also note that six of the younger patients (but none of the adolescents) were diagnosed with residual or recurrent disease despite no evidence of metastasis at the time of surgery, suggesting these patients may have had subclinical extra-thyroidal disease.

Overall, the team believes their findings “obligate consideration of a more aggressive approach to primary treatment and post-operative surveillance of younger children”, and suggest that this age group should be automatically classified as intermediate or high risk.

Eleanor McDermid

Clin Endocrinol 2018; Advance online publication

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