2017 Sec 1 Green Book

188 / 232

most common head and neck malignancy in the pediatric popu-
lation, accounting for 21% of all head and neck cancer in pediatric
patients [3]. Differentiated thyroid carcinomas in children include
papillary, follicular, and variant subtypes. Specifically, the papillary
subtype accounts for approximately 90% of pediatric thyroid car-
cinomas and maintains an excellent prognosis, which parallels
findings in the adult literature [3]. The overall prognosis of pediatric
thyroid cancer may be skewed due to the large number of papillary
thyroid cancer diagnoses, which inherently yield excellent out-
comes [4]. Very few studies have stratified each variant subtype by
disease speci fic survival to determine if this statistical finding is, in
fact, true [6].
Of the differentiated thyroid carcinomas, follicular subtype is
less common in children, but is considered more aggressive and
maintains a poorer prognosis if vascular invasion is present [3] . Also
of note, medullary thyroid carcinoma in pediatric patients is asso-
ciated with markedly shorter mean survival even if individual risk
factors such as metastatic spread or lymphovascular invasion are
absent [6]. Among those diagnosed with thyroid carcinomas, pe-
diatric patients present with more advanced manifestation of dis-
ease than adult patients, yet mortality is comparatively infrequent
[4,6]. In the pediatric population, thyroid carcinomas typically
present in teenage years, especially in Caucasian females, with a
mean age of diagnosis of 16 years [6] . Previous studies have char-
acterized the female predominance of pediatric thyroid carcinomas
and have identified papillary carcinoma as the most common his-
tological subtype within this population [3,6].
Currently, the American Thyroid Association Guidelines dictate
that there is no indicated disease screening for thyroid cancer in
the pediatric population aside from genetic testing and periodic
ultrasound evaluation for patients with mutated genes such as
BRAF, RET oncogene mutations (MEN2A/2B), Cowden Syndrome,
Werner Syndrome and PTEN Related Syndromes. Further consid-
erations include patients who received radiation for Hodgkin
Lymphoma, Leukemias and CNS Tumors especially with radiation
doses between 20 and 29 Gy [7e9,11]. The American Thyroid As-
sociation Task Force on Pediatric Thyroid Cancer reports insuffi-
cient evidence for utilizing ultrasound to screen for non-palpable
thyroid nodules in patient populations not already described due to
the likelihood of false positives associated with an enlarged thymus
or simple cysts [9,11]. As such, pediatricians and otolaryngologists
are forced to rely on early identi fication of neck masses by physical
examination in order to yield the excellent prognosis for pediatric
patients currently described in the literature [9]. While mortality is
rare, past studies have identified factors associated with poorer
prognosis of well-differentiated pediatric thyroid carcinomas, such
as presence of distant metastases, large primary tumor size, lym-
phovascular invasion, and male sex [5,6]. Interestingly, one recent
study has demonstrated that the V600 BRAF mutation implicated
in adult papillary thyroid carcinoma does not significantly
contribute to the development of pediatric thyroid cancer at the
same rate as currently described in older cohorts [10] . The findings
of this study are significant because they provide primary care
providers with a more re fined risk factor approach when evalu-
ating patients [8].
This population-based analysis is imperative since children
maintain a greater chance of recurrence of differentiated thyroid
cancer compared to the adult population [9]. Thus, our group
analyzed the new SEER Database updates provided up until the
year 2012 and compared them to the current literature to deter-
mine if there have been any signi ficant changes in incidence and
disease specific survival based on the various risk factors reported
in previous studies [10]. This study provides the most recent
analysis of the SEER database with respect to pediatric thyroid
carcinoma.
2. Materials and methods
2.1. Description of source database
This manuscript was deemed exempt from Georgetown Uni-
versity IRB review due to the use of de-identified data and was
approved for data collection. The Surveillance, Epidemiology and
End Results (SEER) Database was queried to identify pediatric pa-
tients with pathologically confirmed “thyroid carcinoma” between
0 and 19 years of age from the years 2007e2012. The SEER Data-
base, available at: “seer.cancer.gov”, provides the public with
population-based data regarding cancer incidence, frequency, and
disease speci fic survival data from 1973 to 2012. At this time, the
SEER database includes approximately 10% of the United States
cancer population and is updated annually by the National Cancer
Institute coding technicians. The SEER registry includes patient
information from Atlanta, Connecticut, Detroit, Hawaii, Iowa, New
Mexico, San Francisco, Louisiana, Seattle, Utah, Los Angeles, Alaska,
and San Jose in order to provide its users with a normalized dis-
tribution of patient cohorts in terms of geographic location and age
groups.
2.2. Patient cohort selection
The SEERstat analysis program was downloaded from “seer.-
cancer.gov” as previously described. Our study group utilized the
“Incidence - SEER 18 Regs Research Data þ Hurricane Katrina
Impacted Louisiana Cases 1973e2012 ” database and performed a
multivariable frequency analysis to determine the total number of
patients with the below described pediatric thyroid subtypes. Each
specific thyroid cancer subtype was queried using the following
criteria: “malignant behavior”, “known age”, “cases in research
database” for the initial query. Additional clinicopathologic factors
including age, sex, ethnicity, extent of disease, and lymphovascular
invasion were also included within the aforementioned multivari-
able outcomes query.
Within the Case Selection Statement, the following search lim-
itations were applied to obtain frequency data regarding our pa-
tient cohorts: Pediatric Thyroid Subtypes, “Papillary”, “Follicular”,
“Medullary”, and “Papillary Follicular Variant.” Coding for each of
the described thyroid carcinoma subtypes were collected from the
SEER Database Manual and inputted into the Case Selection Com-
mand Feature [9]. Tumor recurrence events were not available in
the SEER database at the time the query was performed and
consequently were not included. Patients that expired within the
first four months after surgery were excluded since these in-
dividuals were likely unable to complete a full course of radioactive
iodine uptake or external beam therapy. Patients with uncoded
primary tumor subsite were excluded from this study as well as
those with anaplastic thyroid carcinomas and non-epithelial can-
cers, such as lymphomas, due to paucity of data. The cohort was
then further subdivided according to treatment modality into a
“surgery alone” group and “surgery with adjuvant radiation” group,
which included individuals who received radioactive iodine uptake
as well as those who received external beam therapy.
2.3. Statistical analysis
2.3.1. Fifteen-year disease speci fic survival curves
Fifteen-year disease speci fic curves were generated for the
surgery group and surgery with adjuvant radiation group utilizing
the SEERstat, “Survival Session” search query. Within the survival
session, the Observed Survival “Method” was employed to include
fifteen years with intervals of twelve months. Exclusion criteria
included: “Alive with No Survival Time” and “All Death Certificate
S. Dermody et al. / International Journal of Pediatric Otorhinolaryngology 89 (2016) 121e126
166