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Only and Autopsy Only” in order to prevent the inclusion of pa-
tients who would skew the disease specific survival calculations.
Data was then combined for each of the pediatric thyroid subtypes
and standard error of the mean and 95% confidence intervals were
calculated. Disease specific survival data points at each study in-
terval were compared using T-Test analysis to determine significant
difference between the treatment groups.
2.3.2. Statistical analysis calculations
Statistical analysis was performed utilizing the Minitab Inc.
software (State College, PA) to determine statistical differences
between treatment groups. Fifteen-Year Disease Specific Survival
data was compared utilizing the Student's T test to determine
benefit of each treatment modality. The log rank test was not uti-
lized for statistical comparison because the disease specific survival
curves do not reflect a patient's full life span from the point of
diagnosis, but rather illustrate survivorship at fifteen years from the
time of initial diagnosis. The disease specific survival calculations
were weighted similarly to prevent bias of survivorship within the
earlier or later time periods. Calculations were considered statis-
tically significant if P-values were less than 0.05 and 95% con fi-
dence intervals did not overlap between the two groups of interest.
3. Results
3.1. Patient cohort demographics
A total of 1723 pediatric patients were located in the SEER
Database and further stratifi ed based on age, sex, and ethnicity.
According to our analysis, teenage Caucasian females maintained
the highest frequency of obtaining a diagnosis of thyroid carcinoma
when evaluating rates per 100,000 patients. Furthermore, females
maintained an age-adjusted rate of diagnosis compared to males of
approximately 4.4:1 per 100,000 patients. Lastly, African Americans
and the unspecified cohorts demonstrated less frequent diagnoses
across each age group when compared to the Caucasian cohort
(Table 1).
3.2. Average age adjusted incidence rate of pediatric thyroid cancer
subtypes
The overall age adjusted average rate of pediatric thyroid cancer
from 2007 to 2012 was determined to be 0.59 new diagnoses per
100,000 individuals (see Table 2 ). When evaluating papillary thy-
roid carcinoma, follicular thyroid carcinoma, medullary thyroid
carcinoma, and papillary follicular carcinoma thyroid subtypes, the
average rates of incidence were determined to be: 0.30 (47.6%), 0.14
(23.8%), 0.05 (6.7%), and 0.13 (21.9%) per 100,000 reported patients,
regardless of age, respectively. Furthermore, papillary, follicular,
and papillary follicular variant became more prominent in terms of
frequency of diagnosis as pediatric patients reached the fifteen to
nineteen age groups (Fig. 1). Medullary thyroid cancer was the most
frequent in terms of incidence in the zero to four years of age group,
but subsequently declined once the five to nineteen years of age
group demographics were analyzed (Fig. 1).
3.3. Overall fifteen year disease specific survival of individuals
diagnosed with pediatric thyroid cancer
At fifteen years post diagnosis, the disease specific survival for
each age group, regardless of tumor subtype, demonstrated greater
than ninety percent survival. Specifically, the younger de-
mographics, including the zero to four and five to nine years of age
groups, maintained a fifteen-year disease specific survival of
approximately ninety-nine percent when surgery and radiation
therapy, radioactive iodine uptake or external beam therapy, were
utilized. Interestingly, patients who were diagnosed in the ten to
fourteen and fifteen to nineteen age groups maintained excellent
survival outcomes, yet fifteen-year disease specific survival were
significantly lower compared to the two younger age groups
(p < 0.05). Despite this statistically significant difference, the two
older cohorts still demonstrated a disease specific survival greater
than 95% (Fig. 2).
3.4. Fifteen year disease specific survival based on cancer subtype
and therapeutic intervention
Pediatric patients, regardless of age group, demonstrated
excellent fifteen-year disease specific survival after intervention
with surgery or surgery with adjuvant radiation, radioactive iodine
uptake or external beam therapy. Individuals demonstrated signif-
icantly improved survival outcomes if they underwent radiation
therapy in conjunction with their primary surgery management
regardless of tumor subtype (p < 0.001). The fifteen-year disease
Table 1
Demographics of pediatric patients diagnosed with papillary thyroid cancer as rate
per 100,000 patients from 2007 to 2012.
Age group 1e4 5e9 10e14 15e19
Sex Male 0.001 0.04 0.11 0.31
Female 0.01 0.05 0.36 1.48
Ethnicity Caucasian 0.01 0.08 0.38 0.27
African American 0.00 0.007 0.03 0.08
Unspecified 0.001 0.003 0.05 0.19
Table 2
Demographics of pediatric patients diagnosed with thyroid cancer.
Carcinoma subtype Diagnosis count Frequency of total
Papillary 1014 58.8
Papillary follicular variant 397 23.0
Follicular 173 10.1
Medullary 139 8.1
Fig. 1. Incidence of pediatric thyroid carcinoma based on most frequent subtype per
100,000 as a percent of total cohort. (For interpretation of the references to colour in
this figure legend, the reader is referred to the web version of this article.)
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