This study provides new information on the prevalence of and risk for dependent living in adult survivors of childhood cancer. Survivors in our large, multi-site cohort had a significant 2-fold increased risk of living dependently when compared to siblings, and specific treatment variables, demographic factors, and the presence of medical, neurocognitive, and psychological late effects were predictive of independent living status. Through the relatively unique approach of using SEM in this analysis, we have demonstrated causal pathways connecting these diverse predictors, which may provide insight into points of intervention.
When survivors were compared across diagnostic groups, those diagnosed with CNS tumor and leukemia displayed the greatest risk of dependent living in adulthood. This increased risk may be at least partially explained through the impact of cranial radiation therapy on neurocognitive, physical, and behavioral functioning in protocols for these diagnostic groups. Risk for dependent living status increased with greater cranial radiation exposure (>24 Gy), consistent with previous studies documenting poor adaptive functioning after radiation therapy.20,32
Cranial radiation therapy also had indirect influences on dependent living status through neurocognitive late effects, use of neurologically-directed medication, and mental health concerns. Neurocognitive difficulties, particularly in task efficiency, influenced dependent living through poor mental health, depression, somatization, and use of neurologically-directed medication. These findings document the expected role of neurocognitive functioning on psychological well-being and adaptive behavior of survivors. Readily available pharmacologic approaches to managing neurocognitive late effects do not appear to mitigate risk for dependent living in adulthood. Rather, use of these medications more likely represents a marker for severity of neurocognitive dysfunction, which contributes to dependence into adulthood. Similarly, growth hormone deficiency is also likely a marker of neurologic sequelae from treatment, as endocrine dysfunction is a common late effect of cranial radiation therapy.
Psychological distress influences independent living status. Depression was strongly associated with dependent living, which points to the potentially debilitating impact of mental health problems. While the literature suggests that the majority of childhood cancer survivors are coping well after treatment, previous studies have highlighted that a small but distinct subgroup of survivors experience continued emotional distress.33
These individuals may represent a group at risk for concurrent adaptive skill deficits and dependency in adulthood. Stressors associated with dependency may also influence the likelihood of depressed mood. Given these findings, screening for mental health difficulties and intervention to address depression symptoms early on may have long-term benefit for functional independence in adulthood. While the literature suggests that use of a posttraumatic stress (PTS) model of survivorship may be beneficial in understanding the emotional sequelae of childhood cancer,12,13
PTS symptoms were not associated with independent living status in our analyses.
In our model, difficulties with emotional regulation were somewhat surprisingly associated with an increased likelihood of independent living. Poor emotional regulation is not necessarily associated with emotional distress, but rather implies enhanced emotional lability that may include either positive or negative emotions 34
. Thus, as opposed to a marker of psychological distress, this construct may represent a coping style or a personality trait that may either facilitate relationships with selected mates or make one more difficult to live with, unless that individual is in a selected and committed relationship. Alternatively, individuals who live alone or with selected loved one may be more comfortable in demonstrating emotional lability.
Physical functioning also emerged as an important predictor of independent living. Specifically, poor physical endurance appears to be a direct barrier to independent living, and is influenced by somatization (i.e., shortness of breath, numbness, and weakness), diagnosis/treatment variables, use of neurologically-directed medication, growth-hormone deficiency, and current age. Poor physical functioning has an impact on employment opportunities and income, which may also indirectly impact the ability to live independently.17
The association between endurance and independent living can also be partially explained by the increased risk for neurologic impairment in the survivor cohort. Cranial radiation therapy is associated with quantitative changes in brain integrity,35
and changes in brain integrity are associated with increased symptoms of limited physical endurance.36–38
While survivors with better physical endurance were more likely to live independently, those who were independent were more likely to report lower vitality, which may reflect fatigue associated with the demands of caring for oneself.
Our study is not without limitations. The current cohort was treated between 1970–1986, and given changes in treatment, our findings may have limited generalizability to future outcomes of modern treatment protocols. This may be particularly true for leukemia survivors given that current treatment protocols do not typically involve cranial radiation therapy. Nonetheless, our results do reflect the range of difficulties experienced by the cohort of current adult survivors. As our sample includes only survivors who agreed to and were capable of participating in the CCSS, these findings may underestimate deficits by excluding survivors who are having greater neurocognitive or emotional difficulty. While survivors from racial/ethnic minorities were less likely to live independently than Whites/Caucasians, this may reflect the role of cultural factors in the acceptability of multi-generational households as observed in the US Census data. The CCSS is under-represented in terms of racial minority survivors, limiting the conclusions that can be drawn regarding the impact of specific racial/ethnic identity on independent living. This should be examined in more diverse populations, as understanding the influence of race and ethnicity may provide insights into how to reduce social barriers to independence.
The results of the current study permit the development of a profile of survivors who are at risk for protracted dependent living. Neurocognitive late effects, psychological difficulties, medical late effects (i.e. growth hormone deficiency), and physical functioning play important roles in the independence of survivors during adulthood. Individuals who are less than 6 years of age at time of diagnosis, and who receive cranial radiation are at increased risk for dependent living. Furthermore, those who over of the course of early survivorship develop decreased physical endurance, reduced vitality, depression, and neurocognitive deficits warranting medication management are at greatest risk. From this framework, the development of interventions directed towards supporting the psychosocial, neurocognitive, and physical functioning of survivors may promote transition into independence. Monitoring and intervention for depression, evaluating the efficacy of novel approaches for addressing neurocognitive deficits (e.g., cognitive remediation), and promoting physical endurance through exercise/physical therapy programs will be important areas of study in childhood cancer survivors with potential benefit for independent living in adulthood.