Northeast Florida Medicine
Vol. 66, No. 2 2015
31
Pediatric Oncology
Introduction
The purpose of this article is to provide the clinician with
the knowledge necessary to reach an informed clinical deci-
sion supported by the existing body of literature in the care
of the child and adolescent with thyroid cancer. However,
great difference of opinion continues to exist on almost every
facet of care delivery.These controversies will be individually
addressed, though some bias of the author is acknowledged
when recommendations are givenon individual case scenarios
at the end of the manuscript. For this the author hopes to be
absolved in the reader’s mind of any misrepresentation, for
none is intended. To facilitate understanding of the article
the following are provided for clarity; the term childhood
refers to both children and young adults (up to age 21-25),
both of which are often included in published series of pe-
diatric thyroid cancer; differentiated thyroid cancer (DTC)
comprises the vast majority of childhood thyroid cancer
and is the primary focus of this review; medullary thyroid
cancer (MTC) is briefly reviewed in a separate paragraph;
several review articles are used as references – the reader is
encouraged to refer to these for references to the original
supportive scientific publications.
Incidence and Risk Factors
Thyroid cancer is rare in childhood accounting for only
three percent of all solid tumor malignancies in children
and two percent of all thyroid cancer cases regardless of
age.
1,2
However, whereas DTC in preputeral children
accounts for only one percent of solid tumors in this age
group, this rises to seven percent in adolescents and fe-
male predominance becomes more pronounced.
2
Annual
incidence rates are approximately 1/1,000,000 prior to
puberty, rising to 30/1,000,000 in adolescent girls and
6/1,000,000 in adolescent boys.
3
The predominant his-
tologic variant of DTC is papillary (PTC), accounting
for 80 percent of tumors, with follicular (FTC) making
up 20 percent.
1
Significant variants of PTC include the
follicular variant, the diffuse sclerosing variant and the
solid variant, the latter two being associated with increased
aggressiveness.
2,4
The classic papillary histology is found in
older children, but the solid variant is more common in
children less than 10 years of age.
5
The association between
radiation exposure and DTC is well known and includes
both external radiation exposure and internally absorbed
radio-iodide exposure.
6
First reported by Winship and
Rosvall in 1961, this association resulted in preventing
further use of radiation to treat common pediatric benign
diseases.
3
More recently the Chernobyl disaster in 1986
again demonstrated radiation as a direct cause of DTC.
Incidence rates in nearby contaminated areas increased
to 6.2/1000, with the majority being the aggressive solid
variant of PTC.
4
The relatively iodine deficient population,
with resultant increased thyroid absorption of ingested RAI
in the contaminated areas, was felt to be a contributing
factor as well.The increased risk of a second malignant neo-
plasm (SMN) in childhood cancer survivors is well known.
Standardized incidence rates (observed over expected) for
thyroid cancers following treatment for leukemia, hodgkins
lymphoma and non-hodgkin’s lymphoma were 18.8, 52.5
and 40.4 respectively in a review of 16,540 patients from
13 international tumor registries.
7
A review of childhood
cancer survivors from the ChildhoodCancer Survivor Study
(CCSS) also found excess incidence of thyroid cancers
among 14,054 patients.
8
Furthermore researchers were
able to associate radiation exposure to the occurrence of
SMNs in this cohort at a relative risk of 2.5 and noted an
Pediatric Thyroid Cancer
By Daniel K. Robie, MD, FACS
Address Correspondence to:
Daniel K. Robie, MD
Division of Pediatric Surgery
Nemours Children’s Clinic
807 Children’s Way
Jacksonville, Fl 32207
Abstract:
Thyroid cancer in children and adolescents occurs far
less frequently than in adults, but is more locally advanced and has
a higher incidence of distant metastases at presentation. Risk factors
for more aggressive disease are age, specifically young children (<10
years of age), radiation associated tumors, the solid or sclerosing
histologic variant and the RET/PTC3 gene rearrangement.
Thorough examination, neck ultrasound and whole body scanning
with radioiodine are essential to define the extent of disease. Total
thyroidectomy with central lymph node dissection, followed by
RAI (radioactive iodine) therapy, is the treatment of choice, with
more extended formal lymphatic dissection required for those with
palpable or ultrasound (US) identified lymphadenopathy. Surgical
complications can be reduced in the hands of experienced surgeons
and with parathyroid autotransplantation, when appropriate. RAI
carries short and long term risks associated with size of dose and
accumulative dose. Close surveillance and long term follow-up are
critical due to the high incidence of local and systemic recurrence.
Paradoxically, despite more advanced disease at presentation and high
incidence of recurrence, childhood thyroid cancer has a long term
survival over 90-95%.
1
