Introduction
Brain tumors are the most common type of solid tumor in
children.1 Radiation treatment is a life-saving
intervention that can be associated with neurocognitive, emotional, and
behavioral sequalae,2-7 although the use of proton
radiation treatment (PRT) has yielded more favorable outcomes due to its
dose-sparing properties.8-10 Many studies examining
the outcomes of PRT revealed cognitive and adaptive functioning in the
normal range more than 3 years post-treatment;11-13however, adaptive functioning challenges at 5 years post-PRT have been
observed, with greater vulnerability in survivors treated with
craniospinal irradiation (CSI).12 Studies of
psychosocial and executive functioning outcome following PRT in
pediatric brain tumor survivors are relatively recent, and require
replication to strategically guide intervention. Challenges with social
functioning have been described,14 most notably in
aspects of peer exclusion and isolation. While post-PRT studies
examining executive functioning have revealed normal functioning as a
group,15-16 relative weaknesses in processing
efficiency15-16 were observed and may contribute to
functional limitations among some
patients.
Studies have revealed higher rates of internalizing emotional problems
characterized by depression and anxiety following conventional
radiation17-19 whereas externalizing behavior problems
(aggression, defiance) are not elevated,20-21 with
rates lower than the normative mean.22 Greater
inattention (internally experienced symptom) has been reported on parent
questionnaires, whereas greater hyperactivity (externally observed
behavior) has not. 23-24 As a whole, pediatric
survivors treated with radiation tend to experience higher rates of
symptoms that are experienced inside one’s mind (internalizing) rather
than symptoms that are more readily observed and directed towards other
people (externalizing).
Social functioning is also impacted at higher rates following radiation
treatment with higher rates of social
isolation,6,23,25 reduced social
acceptance2,26 and withdrawal.17Pediatric brain tumor survivors were significantly less likely to be
able to name a friend compared with youth who underwent treatment for
non-central nervous system (CNS) tumors,27 suggesting
that treatment-related factors (e.g., school absence, reduced
socialization) cannot fully account for their challenges. Reduced
leadership skills among survivors have also been
described.2,23 Studies have collectively demonstrated
weaknesses in social responsiveness and engagement levels, rather than
deficits in social skills themselves. A recent post-PRT study examining
social functioning observed challenges with social relationships
characterized by social exclusion and reduced amount of
friendships.14
Executive functions are a group of higher ordered cognitive skills that
represent a constellation of behaviors required for task completion and
goal-directed behavior.24 Executive functions are
mediated by frontal-subcortical-cerebellar white matter circuits which
are highly susceptible to injury from radiation
treatment,28-29 affecting the developmental
trajectory. Executive functioning is affected at higher rates following
radiation compared to the general population.20,22,25,30-32 Ecological assessment using
parent-report is a valuable method to capture executive functioning
abilities in daily contexts.33 Parent reports have
revealed greater levels of executive dysfunction in pediatric brain
tumor survivors following radiation treatment, most notably in
metacognitive executive skills: working memory, planning/organization,
and initiation.19, 34-35 Reports of difficulty with
behavioral dysregulation are mixed, with some studies citing
significantly more difficulty34,36 and others
reporting lower rates of behavioral dysregulation.37Fewer problems with inhibition have been
reported.19,35
Several specific risk factors may lead to adverse outcomes for pediatric
brain tumor survivors. Younger age at diagnosis and treatment is a high
risk factor for greater
neurocognitive,12,13,22emotional, and behavioral22,37 sequalae. The extent of
radiation (CSI vs. focal) also impacts cognitive
outcomes,12,13,38 including executive
functioning.15 Socioeconomic status (SES) can
adversely impact functional outcomes in pediatric oncological
survivors,39 including pediatric patients diagnosed
with brain tumors.40-41 Examination of risk factors
following post-PRT is important to guide psychosocial treatment for
pediatric survivors treated with PRT, as current studies reveal
inconsistent relationships with specific treatment and demographic
variables.12-16 Identifying predictive variables can
help direct interventions to those most vulnerable.
The goal of the current study was to examine whether pediatric brain
tumor survivors treated with PRT had problems with psychosocial and
executive functioning at follow-up. The study examined demographic,
diagnostic, and treatment-related variables to identify those patients
at high risk for adverse outcome. For the purposes of this study,
psychosocial is broadly defined to include emotional, behavioral,
adaptive, and social domains of functioning. Executive functioning was
also examined given report of post-radiation impact in the
literature.12,14,16 It was anticipated that: 1)
psychosocial and executive functioning for the total sample would be
within the normal range; 2) significant problems with behavioral
dysregulation and externalizing behaviors would not be seen; 3) a longer
time interval between PRT and follow-up would be associated with greater
problems, and 4) demographic factors would impact outcomes.