Worldwide, more than 175,000 new cases of childhood cancer are diagnosed each year.

Georgie Johnstone, a recent vacation scholar at the Trauma Recovery Lab talks you through some thought-provoking new research on cancer and PTSD.

Overall, in children under 15 years living in the industrialised world, childhood cancer is the 4th most common cause of death. However, childhood cancer is no longer the death sentence it once was, with overall survival rates in high-income countries now at about 80 percent.

How are survivors affected by the potentially traumatic experience of their diagnosis and treatment, and how does it impact on the rest of their life and that of their family? Research has indicated that cancer survivors are at an increased risk not only from somatic late effects related to cancer and treatment, but also for depression, anxiety and antisocial behaviour. Lifetime prevalence of cancer-related PTSD has been estimated at 20-35% in survivors and 27-54% in their parents. However, new research in the Journal of Clinical Oncology has challenged these estimates.

The risk of a focusing illusion
The authors believed that previous PTSD studies had potentially created a ‘focusing illusion’, where the participants were cued to the cancer as a traumatic factor prior to reflecting on their mental health. Participants were therefore more likely to identify cancer as a traumatic event over other life events. This may lead to exaggeration of the importance of cancer as a traumatic event that influences their functioning and, consequently, their reports of their psychological state.A previous study that did not prime respondents to cancer as traumatic, found that less than 10% of children actually spontaneously identified their cancer experience as traumatic.

In the recent study at St Jude Children’s Research Hospital in Tennessee, over 250 participants diagnosed with cancer were compared to peers, and assessed for PTSD (diagnosis) via both parent and child interviews and for PTSS (symptom levels) via survey. About half of the children identified a cancer related event as their most traumatic, with this proportion differing significantly as time passed since diagnosis. Children <5 years since diagnosis identified cancer as their most traumatic event more than 50% of time, while only 23.8% of those >5 years since diagnosis did so.

Parental report also differed by time since diagnosis, with parents identifying cancer as their child’s most traumatic event in 75 % of cases <5 years since diagnosis, decreasing to 47.6% when >5 years since diagnosis.

Findings indicated very low PTSD/PTSS levels: the prevalence of current PTSD was only .4% and the lifetime prevalence of PTSS was 2.8%, numbers comparable to those in community samples. No evidence was found for an elevation in PTSS in youths with cancer in comparison to community peers.

The removal of the ‘focusing illusion’ in this study showed that perhaps cancer does not create the level of the traumatic stress in children that has been previously noted. When creating studies, especially questionnaires or introductory statements, practitioners should be aware of the potential impacts of signposting cancer as a traumatic event.

Contradictory evidence from Denmark
The study is seemingly contradicted by a large-scale study in Denmark that examined the long term risks of mental disorders in survivors of childhood cancer and their siblings. The analyses involved a sample of over 7000 children, comparing two groups from the Danish Cancer Registry and the Family Database with two population-based cohorts who were not (siblings of) childhood cancer survivors. Participants were grouped according to their cancer type, with three main diagnostic groups established: CNS tumours, solid tumours and haematological malignancies.

Overall, it was found that survivors of any of the cancer types were at increased risk for hospital contact for neurodevelopmental, emotional and behavioural disorders. Children younger than 10 years at the time of the cancer diagnosis had the highest risk. Specifically, survivors of CNS tumours were at an increased risk for organic psychosis (psychosis occurring as a symptom of the cancer), and males with any cancer were at an increased risk for unipolar depression.

Across all groups, siblings were at no increased risk for hospital contact, based on gender, or for any specific psychiatric subtype. Interestingly, it was found that the age of the sibling at the time of survivor’s cancer diagnosis was a modifying risk for mental disorders. Young age at diagnosis was associated with an increased risk for hospital contact for behavioural and emotional disorders in both sexes. Siblings who were not yet born at the time of the cancer diagnosis were at the highest risk for mental disorders. This increased risk for unborn siblings may be explained by changes in brain development, as it has previously been found that high levels of maternal stress hormones in utero are associated with an increased risk for depression and schizophrenia.

What to conclude?
It is beyond doubt that children who have cancer and their families should be given psychological support where needed. The Danish study suggests that childhood cancer survivors should be followed up for late mental effects, especially those diagnosed at a young age, as well as their young siblings, to provide the most beneficial outcome for all involved. Although it may appear on the surface that the two studies’ results are contradictory, both plausible results; they utilised different methods to examine different outcomes, with the American study only focusing on (symptoms of) PTSD, compared to the Danish study which looked at hospital contact for mental health issues. The individual differences that they point to, and the fact that PTSD symptoms may be primed, show that good assessment of children’s and siblings’ needs remains essential.

References:
1. Phipps, Klosky, Long, Hudson, Huang, Zhang, & Noll, R. (2014). Posttraumatic Stress and Psychological Growth in Children With Cancer: Has the Traumatic Impact of Cancer Been Overestimated? Journal of Clinical Oncology, 32, 641-646 DOI: 10.1200/JCO.2013.49.8212
2. Lund, Winther, Dalton, Cederkvist, Jeppesen, Deltour, Hargreave, M., Kjær, S., Jensen, A., Rechnitzer, C., Andersen, K., Schmiegelow, K., & Johansen, C. (2013). Hospital contact for mental disorders in survivors of childhood cancer and their siblings in Denmark: a population-based cohort study The Lancet Oncology, 14, 971-980 DOI: 10.1016/S1470-2045(13)70351-6