Population mixing and the risk of childhood leukaemia in Switzerland: a census-based cohort study

Area of Science:

• Epidemiology
• Pediatric Oncology
• Environmental Health

Background:

• Childhood leukaemia (CL) may be linked to infectious agents, suggesting population mixing could elevate risk.
• Understanding environmental factors influencing CL incidence is crucial for public health.
• Previous research has explored associations between CL and population density, but the role of population mixing requires further investigation.

Purpose of the Study:

• To examine the association between childhood leukaemia (CL) and population mixing in Switzerland.
• To determine if population growth, in-migration, or diversity of origin correlates with CL risk.
• To investigate these associations stratified by urbanisation levels.

Main Methods:

• A nationwide cohort study using the Swiss National Cohort (1990-2008) and Swiss Childhood Cancer Registry.
• Inclusion of 2,128,012 children aged <16 years, with 536 CL cases identified.
• Calculation of hazard ratios for CL, acute lymphoblastic leukaemia (ALL), and early-onset CL (<5 years) based on measures of population mixing (growth, in-migration, origin diversity).

Main Results:

• Population growth showed no significant association with CL risk in rural areas but a negative association in urban areas.
• In-migration demonstrated a negative association with ALL risk in both urban and rural settings.
• Diversity of origin did not show a clear association with CL risk.

Conclusions:

• This nationwide cohort study provides limited support for the population mixing hypothesis regarding childhood leukaemia.
• The findings suggest that population dynamics like growth and in-migration may not be significant drivers of CL risk.
• Further research may be needed to explore other potential environmental or genetic factors contributing to childhood leukaemia.