Exploring the Influence of Parental Mental Illness on Childhood Cancer Mortality: A Nationwide Cohort Study in Sweden.

Background: Parents face mental health challenges following their child's cancer diagnosis. However, it is unknown whether parental mental illness following a childhood cancer diagnosis influences the child's mortality.

Patients and methods: Using several nationwide registers in Sweden, we identified children diagnosed with cancer between ages 0 to 14 from 2005 to 2016. Parental mental illness was determined from the National Patient Register, Prescribed Drug Register and primary health care data, which was based on hospitalization records, specialist clinic visits, or prescribed medication for mental disorders after the child's diagnosis. Time-dependent Cox regression models were used to examine the association between parental mental illness and child survival, adjusting for potential confounders.

Results: Among 2,867 children diagnosed with cancer, 1,801 (62.8%) had parents who experienced mental disorders following the diagnosis. Children with affected parents had a 47% higher mortality risk (adjusted HR, 1.47; 95% CI, 1.18-1.84) compared with children whose parents remained free of mental illness. The risk increased to 2.16 (95% CI, 1.58-2.97) for children with both parents affected. Notably, children whose parents had no prior history of mental disorders but developed newly onset mental illness after the diagnosis had a 77% higher risk of mortality risk (adjusted HR, 1.77; 95% CI, 1.33-2.36) compared with those whose parents remained free of mental illness throughout the follow-up period. Landmark analysis findings were consistent with primary results.

Conclusions: Parental mental well-being following a child's cancer diagnosis can significantly impact the child's survival. Addressing parental mental illness, particularly when it emerges after the diagnosis, is crucial for improving child prognosis. These findings strengthen the call to action for targeted interventions that support parental mental health as an integral component of pediatric cancer care to improve child outcome.