cancer , as the second - leading cause of death in the pediatric population of the united states , accounts for a significant number of deaths among the pediatric population . among several different cancer categories identified in this population , head and
neck tumors account for approximately 5% of all reported pediatric tumors . although the majority of head and neck masses in children are inflammatory , etiologies may include congenital or neoplastic lesions .
gurney et al . reported that the overall prevalence of head and neck tumors within the infant and adolescent populations is significantly low .
states that over the last 3 decades , the incidence rates of cancer in the pediatric population have increased with certain malignancies , such as lymphomas and rhabdomyosarcomas . however , due to lack of information , whether this trend can be applied to head and neck cancers remains unclear .
there are differing opinions among authors and clinicians as to what exactly constitutes head and neck tumors .
prior investigations of these tumors were either limited by a criterion that was not anatomically or histologically exclusive to the head and neck or were focused primarily on a particular race and specific tumor site affected [ 511 ] .
for instance , neuroblastomas and lymphomas are the most common head and neck malignancies among infants , children , and adolescents .
however , neuroblastomas are typically considered neuroendocrine neoplasms not specific to one location , while lymphomas are neoplasms of the immune system . in essence
, there are many overlapping definitions , and neither of the cancer types is exclusive to the head and neck .
additionally , rhabdomyosarcoma , a soft - tissue sarcoma with one - third of the cases seen in the head and neck region , may be histologically identified as skeletal muscle tumors that can originate anywhere .
therefore , rhabdomyosarcoma can not be categorized exclusively as a cancer of the head and neck .
investigation of head and neck tumors should be devoid of such discrepancy and variation ; clarity in the definition and the incidence rates of these cancers is important and should be established .
as such , the national institutes of health ( nih ) has categorized head and neck tumors as squamous cell carcinomas that affect the mouth , nose , and throat . typically , these are sub - categorized as 1 ) the oral cavity , including the lips , front two - thirds of the tongue , gingiva , buccal mucosa , floor of tongue and hard palate ; 2 ) the salivary glands , paranasal , and nasal cavities , 3 ) the pharynx ; and 4 ) the larynx .
these selections were contrived to manage the variations among head and neck cancer classification studies .
thus , through the utilization of the established nih categories , the objective of this study was to identify most common pediatric head and neck tumors , using the seer database , and to compare prevalence rates intra - demographically according to race and age .
the national cancer institute compiles cancer related data made publicly available as the surveillance , epidemiology , and end results ( seer ) cancer registry . following the november 2010 submissions , seer 17 covered 26% of the united states population , which included 17 registered areas .
this study utilized the seer database to extrapolate pediatric patient information regarding head and neck cancers .
patients included in this study were infants ( within the first year of life ) , children ( 112 years old ) , and adolescents ( 1319 years old ) diagnosed with head and neck cancers in the united states from 1973 to 2008 . only 11 categories ( lip , tongue , salivary gland , floor of mouth , gum and other mouth , nasopharynx , tonsil , oropharynx , hypopharynx , nose , nasal cavity and middle ear , and larynx ) , distinguished as head and neck cancers according to the classification proposed by the us department of health and human services national cancer institute ( nci ) , were included in this study .
tumors arising from the cns , thyroid , lymphoid , vasculature , scalp , skin , bones , and skeletal muscles of the head or neck are not part of the nci criteria , and therefore were not included in this study . after running a frequency session using the seer 17 database ,
five specific tumor types were shown to account for 95% of reported cases of head and neck tumors : salivary glands ; nasopharynx ; nose , nasal cavity , and middle ear ; gum and other mouth ; and tongue tumors .
since the remaining 6 tumor types combined accounted for only a small percentage , they were grouped under the heading other head and neck tumors .
the data were grouped into twelve 3-year periods of diagnosis : 19731975 , 19761978 , 19791981 , 19821984 , 19851987 , 19881990 , 19911993 , 19941996 , 19971999 , 20002002 , 20032005 , and 20062008 .
covariates of year of diagnosis , site and morphology , age , and race were used .
race was identified as white , black , or other ( american indian / ak native , asian / pacific islander ) .
incidence rates were then calculated as cases per 100 000 population using the seer 9 registry ( 19732008 ) , and age - adjusted incidence rates were calculated using the 2000 us census data for 019 year olds and graphed over 3-year periods from 1973 to 2008 .
these rates were further analyzed by race individually for each of the 6 tumor groups , and collectively for all head and neck tumors .
comparative proportional analysis of incidence rates was done using chi - square test to identify variability of head and neck neoplasms within the individual races , as well as between the 3 race groups .
confidence intervals were calculated to provide the percentile range of differences between white - black , white - other , and black - other ethnic groups .
comparisons were graphed to identify which racial group(s ) had a greater propensity for a particular neoplasm using graphpad prism version 5.04 ( graphpad software inc , 2012 , la jolla , ca , www.graphpad.com/prism ) .
from 1973 to 2008 , the seer registry reported 1088 head and neck tumor cases among pediatric patients 019 years of age .
of these cases , salivary gland ( n=319 ) , nasopharyngeal ( n=311 ) , nose , nasal , and middle ear ( n=208 ) , gum and other mouth ( n=134 ) , and tongue ( n=61 ) neoplasms had the 5 highest prevalence rates of the 11 categories analyzed ( figure 1 ) .
an intra - demographic analysis of prevalence of each head and neck cancer showed that patients within the white racial group overall had the greatest number of cases per 100 000 population .
although white patients had the highest prevalence for most of the tumor categories , the proportion of nasopharyngeal cancer was highest among blacks and others , and hence showed a higher prevalence when compared to white patients ( table 1 ) .
comparative proportional analysis showed differences between whites / blacks for salivary gland tumors , between whites / blacks and whites / others for nasopharyngeal tumors , and between whites / blacks for gum and other mouth tumors . among 319 patients with salivary gland tumors , 246 ( 31.20% ) reported salivary gland cases among whites ( ci=28.034.4% ) , 49 ( 23.80% ) cases among blacks , and 24 cases ( 25.5% ) among others .
when a comparison analysis of frequency proportions was performed , there was a trend toward intra - demographic distribution , specifically between whites and blacks ( ci 0.814.1% ) ( figure 2 ) .
comparison of incidence rates further elucidates the significant difference between whites and blacks ( ci 0.617.1% ) .
comparatively , blacks had a higher proportion of nasopharyngeal cases , with 89 ( 43.2% ) when compared to whites 187 ( 23.7% ) and others 35 ( 37.2% ) .
this suggests that black and other populations have a greater propensity toward developing nasopharyngeal tumors .
proportion analysis of nasopharyngeal cases shows that the incidence rate reiterates the previous data showing a significant proportional difference between whites / blacks and white / others .
blacks ( p=0.406 ) have a greater proportion of nasopharyngeal tumors over time relative to whites ( p=0.239 ) and other ( p=0.397 ) . a comparison of incidence rates between whites - blacks ( wb ) , whites - others ( wo ) , and blacks - others ( bo ) demonstrates that there is likely ( 95% ci , p<.05 ) a greater incidence rate for nasopharyngeal tumors among blacks ( ci=25.8 to 7.6% ) and others ( ci=28.8 to 2.8% ) when compared to whites ( figure 2 ) .
there is also a greater incidence of gum and other mouth tumors among whites when compared to blacks ( ci=4.412.6% ) .
the remaining comparisons had thresholds that crossed the zero line , indicating a likelihood of no difference in frequency or incidence rates .
overall , the incidence of all 11 categorized head and neck tumors from 1973 to 2008 across 3-year intervals showed a positive correlation ( figure 3 ) .
head and neck tumors account for 5% of all childhood cancers . according to albright et al .
, the increase in the incidence of head and neck tumors among children younger than 15 years has exceeded the overall rise in all cancers for this specific age group .
epidemiological studies have shown that inheritable types of cancer form only a minor portion of childhood tumors .
however , previous studies had inconsistencies in defining pediatric head and neck tumors , particularly with the inclusion and exclusion criteria used .
some of these studies have included histological categories not exclusive to the head and neck , such as lymphomas as a part of the head and neck tumors , which in turn increased the overall incidence rates of these tumors .
additional analysis of categorization has yielded concerns about head and neck criteria , particularly when analyzing trends in incidence rates .
thus , it was imperative to adopt standard criteria in defining head and neck tumors , such as that offered by the national cancer institute ( nci ) , for this study . from 1973 to 2008 , the inclusion population ( n=788 ) had an overall increase in incident rates , showing a positive correlation ( r=0.3014 ) in head and neck cancers among infants , children , and adolescents .
additionally , from 1985 to1993 , there was a rising incidence in the reported cancers among this age group , followed by a decrease into the early 2000s .
although slight increases and decreases are seen , the overall correlation is positive , and linabery et al .
suggest that factors such as improved genetic screening , increasingly sensitive diagnostic modalities , and increased reporting among races accounts for the overall increase in reported incidence .
bleyer also states that during the last 25 years , the incidence of cancer in this age range has increased faster , while the increase of cancer survival rates has been significantly slower than in younger or older patients . from the data in this study ,
the 5 highest incidence rates and relative frequencies of squamous cell carcinomas of the head and neck region were found in : ( 1 ) salivary glands , ( 2 ) nasopharynx , ( 3 ) nose , nasal cavity , and middle ear , ( 4 ) gum and other mouth , and ( 5 ) tongue . of
further investigation of intra - demographic incidence rates of the top 5 tumor sites indicated white patients had the greatest overall prevalence of the above - mentioned tumors .
unique intra - demographic differences among salivary gland , nasopharyngeal , and gum and other mouth tumors were also significant [ 2124 ] .
the data from this study shows that salivary gland tumors had the greatest incidence of all reported cancers within the identified categories .
sultan et al . presented information pertaining to salivary gland tumors and identified the peak incidence at 15 years of age .
other studies indicated that tumors , in comparison to inflammatory diseases affecting the salivary gland , are quite rare , with an annual incidence of 1 per 100 000 cases .
it is vital to consider that although salivary gland tumors are relatively rare , the incidence within the white pediatric population is significantly higher than for any other racial group . when analyzing the incidence rate for each specific tumor type intra - demographically , comparisons ( figure 3 ) that included zero in their ranges , indicating a p value greater than 0.05 , showed no statistical difference between races .
such a difference was identified and showed that ( figure 3 ) whites ( ci=0.814.1% ) have more salivary gland tumors relative to blacks and other races .
the analysis of nasopharyngeal tumors showed a greater propensity among blacks and other races relative to the white population .
presenting at a median of 13 years of age , nasopharyngeal tumors have been historically exhibited at incidences 30 times greater in southeastern asia in comparison to the incidence found in the united states .
the opposing rate values seen in this study were not a surprise , as it had been noted in prior studies .
these studies showed black pediatric patients in the united states , when compared to asian pediatric patients , have an incidence rate ratio to white patients for nasopharyngeal cancers of 1.69 per 100 000 versus 0.95 , respectively .
finally , there were 134 reported cases of gum and other mouth tumors from 1973 to 2008 . despite the small population size
, comparisons of white and black ( ci=4.4% to 12.6% ) showed a ci not including zero , thus indicating that whites have a greater tendency to present with gum and other mouth tumors .
the remaining tumor site comparisons either expressed no significant differences between the groups , or the population size was too small to make a comparison .
the limitations of the present study include the narrow scope of the search and lack of information on the contributors of incidence change .
while these limitations exist , it was the focus of the study to determine the incidence rates of tumors exclusive to the head and neck .
it is also critical to note that although the incidence rates have been identified along with intra - demographic comparisons , there are still many unknowns regarding the etiology of pediatric head and neck tumors , thus the inability to note the contributors of incidence changes .
etiological presumptions may be made and include , among all races , environmental and exogenous exposures , such as cigarette smoking , excessive alcohol consumption , viral susceptibility , congenital abnormalities , and genetic dysregulation [ 22,2628 ] .
between 1973 and 2008 , the 5 most common head and neck cancers among infants , children and adolescents were ( in order of prevalence ) : salivary gland ; nasopharyngeal ; nose , nasal cavity , and middle ear ; gum and other mouth ; and glossal tumors .
relative to intra - demographic comparisons , whites have the greatest overall incidence of these conditions , particularly salivary gland , gum , and other mouth tumors .
however , blacks and other racial populations have a greater proportion of nasopharyngeal tumors when compared to the white population .
while the scope of the current study did not include data on staging of disease , survival rates , or treatment , it is critical that future projects provide up - to - date analyses of pediatric head and neck tumors .
it also remains to be seen if future researchers will adopt the criteria set forth by the national cancer institute , and whether previous classifications will be re - adopted under those new categories . if the classification criteria continue to overlap and consensus is not reached between studies , then the identification of head and neck tumors among pediatric populations will remain relatively inconsistent .
it is necessary for clinicians and researchers to utilize a system that is consistent and yields statistical information that is clinically representative and accurate of all pediatric head and neck tumors .
more importantly , the rise in head and neck tumors among pediatric patients between 1973 and 2008 is alarming , and the identification of risk factors to prevent future increase is important . among data obtained in this study ,
racial differences in incidence rates recognize ethnic background as a significant risk factor for pediatric head and neck tumors ; a significant finding that may contribute to future research .
 backgroundthe aim of this study was to determine the most frequently presenting tumors exclusive to the head and neck within the pediatric population , and to identify racial disparities within the existing incidence rates.material/methodsthe population - based surveillance , epidemiology , and end results ( seer ) registry was utilized to identify the frequency and incidence rates of various tumors found exclusively in the head and neck , diagnosed between 1973 and 2008 in pediatric patients . 
 the tumor categories were based on those defined by the us department of health and human services national cancer institute ( nci ) . 
 proportional comparisons were applied to evaluate the intra - demographic incidence rate differences.resultsamong the 11 categories defined , the 5 most prevalent head and neck cancers within the pediatric population were salivary gland tumors ( n=319 ) ; followed by nasopharyngeal neoplasms ( n=311 ) ; tumors of the nose , nasal cavity and middle ear ( n=208 ) ; gum and other mouth tumors ( n=134 ) ; and glossal tumors ( n=61 ) . 
 proportional comparisons between racial frequency rates indicated that salivary gland tumors were greatest among white pediatric patients ( n=246 , ci=0.8 to 14.1% , p<.05 ) . 
 nasopharyngeal cancers were highest among blacks ( ci=26.8 to 12.1% ) and other races ( ci=23.6 to 3.4% ) relative to the white population.conclusionssalivary gland tumors were the most commonly seen head and neck tumors overall among pediatric patients between 1973 and 2008 . 
 incidence rate differences between white , black , and other racial background pediatric patients revealed that overall , head and neck tumors are most prevalent among pediatric patients within the white ethnic population , while nasopharyngeal tumors showed a strong prevalence in blacks and other ethnic populations . 
Background
Material and Methods
Results
Discussion
Conclusions