84th Annual Meeting of the American Thyroid Association:

Thyroid Nodules and Thyroid Cancer in Pediatric Endocrinology

The evaluation and management of thyroid nodules and thyroid cancer in pediatrics was the topic presented by Stephen Huang, MD, Professor of Pediatrics at Harvard Medical School and Associate Physician in Medicine at Boston Children’s Hospital, Division of Endocrinology. Several of Dr. Huang’s comments reflect what will be published in the pediatric consensus guidelines.

Prevalence
The occurrence of thyroid nodules is uncommon in children, although the frequency increases with age. Approximately 4% to 7% of adults have a palpable thyroid nodule. By comparison, the prevalence of thyroid nodules in children is 0.05% to 1.8%. Dr. Huang said, “Early pediatric series were notable for reports of very high cancer prevalence, as high as even 70%. But no series from the mid-1980s forward seem to cite the lower cancer prevalence in children of around 20%. It’s more similar to the cancer prevalence of the adult population.”

Diagnosis
Management of thyroid cancer centers on the patient’s prognosis, which is determined from the size and type of the cancer at diagnosis. Ultrasound and fine-needle aspiration (FNA) are the diagnostic gold standard. Diagnostic evaluation is the same for adults and children. “In the upcoming 2014 American Thyroid Association (ATA) Guidelines, there’s also a specific recommendation to use FNA in reticular ultrasound evaluation,” noted Dr. Huang.

Suspected Thyroid Nodule: Diagnostic Steps

  • Medical history: Prior childhood neck irradiation increases thyroid cancer risk.
  • Family history of thyroid cancer, endocrine tumors, especially medullary thyroid cancer.
  • Suspicion of non-medullary thyroid cancer (eg, PTEN Hamartoma Tumor Syndrome/ Cowden’s Disease/ Cowden’s Syndrome).
  •  Examination: Nodule(s) fixed to an adjacent structure(s) or growing in size are of concern.
  • Scintigraphy with either radioiodine or technetium
  • Ultrasound, which allows a nodule (or nodules) to be followed

Dr. Huang stated, “The diagnosis of nodular autonomy requires that you see uptake of the tracer into the nodule itself even when the patient’s serum TSH [thyroid-stimulating hormone] is low. If you’re confident that you have that pattern, you’ve diagnosed an autonomous nodule [rare]. And as the majority of those are benign, that can be considered reassurance against cancer risk.” A patient with a normal or high TSH requires prompt imaging, and if the lesion is of size, it should be biopsied.

According to Dr. Huang, in a study conducted at the Brigham and Women’s Hospital of 173 adults with suspected masses, ultrasound alone demonstrated either no nodule or met the criteria for biopsy. Biopsy needle guidance with ultrasound guidance images the lesion(s), great vessels, trachea and other structures and enhances procedural safety.

Thyroid Cancer
Similar to the incidence of thyroid nodules, the incidence of thyroid cancer is less common in children than in adults. Survival rates are quite good. “Often that’s attributed to the concept that many young children with thyroid cancer have excellent avidity for radioiodine and appear to be very radio-sensitive, stated Dr. Huang. However, very few pediatric series follow the patients past childhood, so we may underestimate mortality.

In the management of papillary cancer, surgery is the primary treatment. In pediatrics the operative risks differ, which Dr. Huang pointed out was established by multicenter studies in the 1980s and 1990s. These studies showed the risk for serious complications were not only related to the extent of surgical resection, but inversely related to the patient’s age at the time of surgery. Individual surgeon experience is probably one of the most critical determinants of operative risk.

“In some cases it will be best if a thyroid surgeon is given privileges to operate on children in concert with pediatric anesthesia. At other sites there will be a pediatric surgeon and an adult thyroid surgeon operating together. At our center we sort the different combinations, and see that our pediatric surgeons work very close with the adult thyroid surgeon. We prefer that the young surgeon spend a year training in a common fellowship just to get the techniques in his head.” —Stephen Huang, MD

Adjunctive Therapy
Most papillary follicular thyroid cancers have mean expression of the TSH receptor, therefore they have TSH-dependent growth. For that reason, suppression of serum TSH alone is corrective. It’s one of the mainstays in the chronic care of patients with thyroid cancer to reduce their risk of disease progression to recurrence, because most differentiated thyroid cancers alter the gene expression of the sodium-iodide symporter (NIS). NIS can be exploited by the expression of liver radioiodine, either as a diagnostic tracer or with high-dose iodine 131 as a cytotoxic for a disease that is inoperable.

There is an effort to view preoperative data together with the surgical pathology to place patients within categories of risk that allows physicians to predict the likelihood of progression. This enables the physician to individualize adjunctive therapy and monitor their pediatric patients based on that risk. In some respects, this is similar to adult risk stratification.

Conservative Tools to Monitor for Response and Recurrence

  • Serum thyroglobulin
  • Head and neck ultrasound
  • CT imaging
  • Venography and scintigraphy

Resources in Collaborating
“It wasn’t evident to me before I started that in order for this to work well we need to have collaboration across different disciplines,” stated Dr. Huang. It’s helpful to have a pediatrician in pediatric oncology, “… not just for the use of tyrosine kinase inhibitors … but just because they are a lot more sophisticated than I am as a pediatric endocrinologist who is trying to recruit support for families that are dealing with children who are very ill. For this second part I’m thankful for a long period of time, “recalled Dr. Huang.

January 27, 2015

 

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Thyroid Surgery Guidelines for Voice Preservation
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