The link identified by the Danish Cancer Society applies particularly to boys and is regardless of the type of cancer they had. Researchers admit there is no obvious explanation as to why male cancer survivors in particular have an increased risk of being admitted to a psychiatric department.
Through the national Danish disease databases, the researchers from Copenhagen University Hospital have followed 7,085 children who were treated for cancer from 1975-2010, and their 13,000 siblings.
Siblings sensitive to problems in the family
The results also showed a 20% higher risk of mental illness for children who were under the age of five when their brother or sister was diagnosed with cancer. This suggests that children in this early period of development can be particularly sensitive to problems in the family.
On the other hand, siblings who were older than 15 years when their brother or sister got cancer seem to have a lower risk of developing psychological problems than the general public.
Study lead Professor Kjeld Schmieglow, from the department of paediatrics and adolescent medicine at Rigshospitalet’s Juliane Marie Centre, said: “The study stresses the importance of long-term follow-up of childhood cancer survivors in order to help the patients and their families as best as possible during and after treatment,” he said.
The study concludes that this higher risk of psychological problems for children who have survived cancer stresses the need to continue following the children from the day they are diagnosed with cancer and regularly thereafter.
"Therefore, we must prepare guidelines for how and how often children should be monitored and offered support so that we can prevent mental illness,” said fellow researcher Lasse Lund.
"Siblings react to their parents’ anxiety and worries about whether the sick child will survive. Therefore, parents and physicians providing treatment must be aware that younger siblings also have a higher risk of developing psychological problems."
The risk of developing a mental illness is higher even 20 years after the children have discontinued their cancer treatment, although the risk is highest for children who were diagnosed with cancer before the age of 10, according to the findings, which are published in the journal Lancet Oncology.
For full details of the study visit www.thelancet.com