Socioeconomic characteristics and relapse-free and overall survival from childhood cancer - a nationwide study based on data from the Danish Childhood Cancer Registry.

Background and purpose: Over the past decades, childhood cancer survival has increased substantially in Europe, including Denmark. However, families with fewer social resources may have benefitted less from these improvements. In this nationwide register-based study, we assessed associations between parental socioeconomic position (SEP) and 5-year relapse-free survival (RFS) and overall survival (OS) in childhood cancer patients.

Material and methods: All children aged <16 years diagnosed with cancer in Denmark between 1998 and 2017 were identified in the Danish Childhood Cancer Registry (N = 3245). Parents, with whom the children resided, were identified, and data on the parents' education, cohabitation status, affiliation to work market, country of origin, and vital status of the children were obtained through individual-level linkage across Danish nationwide registries. Cox proportional hazards models were used to estimate the association between SEP indicators and 5-year RFS and OS.

Results and interpretation: Tendencies towards lower 5-year RFS and OS were observed among children whose parents were unemployed/not in workforce (RFS: HR [hazard ratio] = 1.14, 95% CI [confidence interval]: 0.90-1.45, OS: HR = 1.28, 95% CI: 0.95-1.71) or from non-Western countries (RFS: HR = 1.21 95% CI: 0.96-1.52, OS: HR = 1.44, 95% CI: 1.09-1.90). Results by diagnostic groups revealed particularly low OS for children with non-central nervous system tumors whose parents were from non-Western countries (HR = 1.92, 95% CI: 1.24-2.97). Targeted strategies are needed to promote social equity and ensure optimal diagnosis, care, and management of childhood cancer across social groups.