New guidelines to call for more selective use of radioactive iodine treatment in pediatric differentiated thyroid cancer

HALIFAX, Nova Scotia — Radioactive iodine treatment should be more selectively used in children with differentiated thyroid cancer, according to guidelines soon to be released by the American Thyroid Association and endorsed by the Pediatric Endocrine Society.

Speaking here at the annual meeting of the Canadian Pediatric Endocrine Group, Steven Waguespack MD, FAAP, FACE, Professor and Deputy Department Chair, Department of Endocrine Neoplasia & Hormonal Disorders at the University of Texas MD Anderson Cancer Center in Houston, explained that thyroid cancer in children can present aggressively but that the prognosis is better in children than in adults. Waguespack is a [SW1] co-chair of the inaugural ATA task force that developed guidelines for pediatric differentiated thyroid cancer.

Steven Waguespack

“[Children] present with a higher likelihood of lymph node and lung metastases,and there is an overall higher chance of recurrence compared with adults," Waguespack said. "However, the long-term prognosis is excellent and one can't assume that a child with thyroid cancer should be treated the same as you would an adult."

Recent studies suggest that the incidence of pediatric differentiated thyroid cancer might be increasing, particularly in adolescents, but long-term disease-specific mortality is quite low, around 2%. One of the theories as to why prognosis is far better for children than for adults is that children do not typically carry the same oncogenic mutations that cause more aggressive disease.

“For example, the prevalence of BRAF mutations in children is quite low compared with adults," Waguespack said.

A major change in recent clinical practice has been less reliance on radioactive iodine to evaluate and treat pediatric thyroid cancer, Waguespack said. Given that accumulating data point to a possible elevated risk of secondary malignancies with radioactive iodine use, and understanding that children with thyroid cancer may develop persistent yet stable disease despite previous therapy, most thyroid cancer experts have started to tailor treatment and reserve radioactive iodine (especially in the retreatment setting) for those children who are most likely to benefit, Waguespack said.

Chief in the successful treatment of pediatric differentiated thyroid cancer is surgery, and the current recommendation is that all children with thyroid cancer be seen at centers with high-volume thyroid surgeons who perform at least 30 procedures annually, Waguespack said.

With less-experienced surgeons performing surgery, which often needs to include compartment-focused neck dissections, the risk of complications is increased and the chance of all malignant tissue being removed is decreased, according to Waguespack.

Post-operatively, pathologic staging and knowledge regarding clinical presentation is used to determine which children should proceed to further evaluation and treatment and which children can be safely monitored without radioactive iodine. “It's a natural evolution in our thought process about the role of radioactive iodine.” Waguespack said.

The upcoming guidelines will recommend that children be stratified post-operatively into low-, intermediate-, and high-risk categories, which will help to predict the risk of residual cervical or distantly metastatic disease and help to guide appropriate strategies for radioactive iodine use and long-term surveillance. – by Louise Gagnon

Reference:

Waguespack SG. Oral Presentation: Differentiated thyroid cancer in childhood: long-term outcomes and new treatment options. Presented at: Canadian Pediatric Endocrine Group Scientific Meeting; Feb. 19-21, 2015; Halifax, Nova Scotia, Canada.

Disclosure: Waguespack reports no relevant financial disclosures.

[SW1]I was one of two co-chairs.