A systematic review and meta-analysis of the association between childhood infections and the risk of childhood acute lymphoblastic leukaemia.

BACKGROUND

To determine whether childhood infections were associated with the development of childhood acute lymphoblastic leukaemia (ALL).

METHODS

We included studies that assessed any infection in childhood prior to the diagnosis of ALL in children aged 0-19 years compared to children without cancer. The primary analysis synthesised any infection against the odds of ALL, and secondary analyses assessed the frequency, severity, timing of infections, and specific infectious agents against the odds of ALL. Subgroup analyses by data source were investigated.

RESULTS

In our primary analysis of 12 496 children with ALL and 2 356 288 children without ALL from 38 studies, we found that any infection was not associated with ALL (odds ratio (OR)=1.10, 95% CI: 0.95-1.28). Among studies with laboratory-confirmed infections, the presence of infections increased the odds of ALL by 2.4-fold (OR=2.42, 95% CI: 1.54-3.82). Frequency, severity, and timing of infection were not associated with ALL.

CONCLUSIONS

The hypothesis put forward by Greaves and others about an infectious aetiology are neither confirmed nor refuted and the overall evidence remains inadequate for good judgement. The qualitative difference in the subgroup effects require further study, and future research will need to address the challenges in measuring infectious exposures.