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.