The prevalence of PTSD, including functional impairment and/or clinical distress as well as symptoms, was more than four times greater in young adult cancer survivors than in a comparison group of siblings. Prevalence of PTSD was associated with many of the specific demographic variables assessed, including marital status, education, employment, income and age at interview. However, the relationship of PTSD to cancer-related variables was more complex. The best predictors of risk for PTSD in the survivors were a composite variable of intensity of therapy or an interaction of age at diagnosis with cranial radiation.
Intensity of treatment, defined similarly as in this study, was not significantly correlated with PTSD in a previous study of 186 childhood cancer survivors (2
). However, other studies have found that brain tumors and treatments (like cranial radiation), which have an impact on cognitive function, were associated with long term emotional distress for survivors (26
). It may be that intensity of treatment in general, and cranial radiation in very young children in particular, is related to late effects which impair function and cause emotional distress. The association of PTSD with lower education, employment and income in survivors would be consistent with this subgroup being one with additional burdens and reminders posed by later physical and cognitive impact of cancer treatment.
The prevalence of PTSD in this study is far higher than the 3% reported by cancer survivors who were still children and adolescents (1
) and is similar to, or higher than, studies that included adolescents as well as adult survivors, where an elevated rate of 10.9% (31
) or a rate similar to controls (32
) was reported. If the symptoms of PTSD are a result of early trauma associated with specific childhood cancer experiences, how could it be that the symptoms are not seen until people are in their thirties and forties? Because none of these prior childhood cancer studies followed survivors longitudinally through childhood and into their thirties and forties, there is no definite answer to this question. It is possible that this and other cross-sectional studies are detecting a cohort effect. For example, newer, less toxic treatments, less reliance on cranial radiation for non-CNS tumors, and better supportive care may mean that younger survivors are now less traumatized and have fewer physical and cognitive late effects than the survivors in the past. This hypothesis appears to be supported by the higher risk of PTSD associated with older age at interview in this study. However, when specifically compared on year of treatment (which was not included as an independent variable in the general analytic model due to co-variance with age at interview) there was no significant difference in risk for PTSD between survivors treated in the 1970s and those treated in the 1980s. The effects of newer treatments and supportive care in the 1990's and 21st
century have yet to be explored.
Another potential explanation for the difference in prevalence of PTSD between children or adolescents and young adults is that the criteria for PTSD are more appropriate for adults than for younger individuals. However, there are many studies of adolescents exposed to a variety of traumatic events which have found that the PTSD criteria can be used with adolescents (33
). A recent study found a prevalence of PTSD symptoms in adolescent recipients of solid organ transplants of 20%, much closer to that seen in the young adult studies of childhood cancer survivors than in the studies of younger cancer survivors (34
). This finding suggests that child and adolescent organ transplant recipients are able to endorse symptoms of PTSD.
It may be that symptoms, clinical distress and functional impairment only emerge among the more vulnerable childhood cancer survivors as they contend with the developmental tasks of young adulthood (35
) and the added challenges of late effects of treatment (29
). The relative protection of the parental home is diminished as young adult survivors face the challenges of completing their education, finding a job, getting health insurance, establishing long-lasting intimate relationships, and starting a family. All of these tasks contain reminders that the survivors may be at a disadvantage relative to their peers as a result of the cancer and its treatment (e.g. due to infertility, decreased height, learning disabilities). The difficulty with developmental tasks may serve to remind the survivors of traumatic events, causing PTSD symptoms, clinical distress, or emotional impairment to surface that have been previously latent. Developmentally expected but difficult stressors (e.g. relationship difficulties, problems with school work, peer pressures, and challenges in finding and retaining employment) may overwhelm coping skills and precipitate the emergence of clinically significant symptoms.
It is not surprising, then, that lower levels of income, employment, and marriage are associated with PTSD in both the survivors and their siblings. Directionality is unclear in this association. People without the social and economic support of a job and partner are generally at greater risk for emotional distress. However, another interpretation is that PTSD is a cause or correlate of difficulty getting and keeping an education, a job or a relationship. PTSD may indicate psychological vulnerability in the survivors. As such, it may be a marker of people who are prone to other adverse life events, and a target population for mental health intervention.
Not all of those contacted for the baseline survey of this study chose to participate, and not all who were invited to participate in the psychosocial component completed these measures, suggesting that there may have been some self-selection in the respondents. Non-participants were younger at diagnosis, more likely to have had cancers of the central nervous system, more often male, younger, less well-educated, and less likely to be employed, married or making more than $20,000 a year. They were also more likely to have scores in the clinically significant range on the Brief Symptom Inventory in depression, anxiety, somatization, and global severity of emotional distress. These findings suggest that those who would appear to be at higher risk for PTSD were also less likely to participate in this study, and that the observed prevalence of PTSD in this study reflects a conservative estimate of the true population affected.