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Patterns of infection and day care utilization and risk of childhood acute lymphoblastic leukaemia
J P Neglia1, M S Linet, X O Shu
1Department of Pediatrics, University of Minnesota School of Medicine, Minneapolis, USA.
Insights
This study found that fewer ear infections in infancy were linked to a higher risk of childhood acute lymphoblastic leukemia (ALL). However, other common childhood infections and daycare exposure did not show a significant association with ALL risk.
Area of Science:
- Epidemiology
- Pediatric Oncology
- Immunology
Background:
- Childhood acute lymphoblastic leukemia (ALL) is the most common childhood cancer.
- The etiology of ALL is not fully understood, but environmental factors are suspected.
- The 'delayed infection hypothesis' suggests reduced exposure to common infections may increase ALL risk.
Purpose of the Study:
- To investigate the association between exposure to common childhood infections and the risk of childhood ALL.
- To examine the role of daycare attendance, sibship size, and specific infections in ALL development.
Main Methods:
- A case-control study was conducted in the US.
- 1842 newly diagnosed cases of childhood ALL (under 15) and 1986 matched controls were included.
- Data on infections, daycare, and sibship size were collected via parental interviews and analyzed stratified by leukemia type.
Main Results:
- Daycare attendance or duration was not associated with ALL risk overall or for 'common' ALL.
- Fewer ear infections in infancy showed a trend towards increased ALL risk (trend P = 0.026).
- No significant association was found between sibship size or birth interval and ALL risk.
Conclusions:
- The findings partially support the delayed infection hypothesis, specifically regarding ear infections.
- Reduced exposure to common childhood infections, with the exception of ear infections, does not appear to increase the risk of childhood ALL.
- Further research is needed to elucidate the complex relationship between infections and ALL etiology.
Abstract:
To investigate if decreased exposure to common childhood infections is associated with risk of childhood acute lymphoblastic leukaemia (ALL) we conducted a case-control study of 1842 newly diagnosed and immunophenotypically defined cases of ALL under age 15, and 1986 matched controls in the US. Data regarding day care, sibship size and common childhood infections were obtained through parental interviews. Data were analysed stratified by leukaemia lineage and separately for 'common' childhood ALL (age 2-5 years, CD19, CD10-positive). Neither attendance at day care nor time at day care was associated with risk of ALL overall or 'common' ALL. Ear infections during infancy were less common among cases, with odds ratios of 0.86, 0.83, 0.71 and 0.69 for 1, 2-4, 5+ episodes, and continuous infections respectively (trend P = 0.026). No effect of sibship size or birth interval was seen. With one exception (ear infections), these data do not support the hypothesis that a decrease in the occurrence of common childhood infection increases risk of ALL.