Association of Childhood Acute Leukemia With Autoimmune Diseases.

Emerging evidence indicates a possible association between acute leukemia and type 1 diabetes mellitus (T1DM). However, the relationship between acute leukemia and other autoimmune diseases (AIDs) remains less well understood. To address this gap, we conducted a case-control study using detailed Finnish register-based data. We identified 1626 childhood leukemia cases (diagnosed 1990-2019) from the Finnish Cancer Registry and sampled three age- and sex-matched controls per case. Information on 29 AIDs, based on previous literature, was obtained from the Care Register of the Finnish Institute for Health and Welfare and on T1DM from the Social Insurance Institution of Finland. Subjects with Down syndrome were excluded. Conditional logistic regression, adjusted for maternal smoking and large for gestational age, was used to estimate associations. After excluding T1DM, AIDs remained associated with an increased risk of childhood leukemia (OR 1.8, 95% CI 1.4-2.4), the association primarily driven by acute lymphoblastic leukemia (OR 1.9, 95% CI 1.4-2.6). Of the AIDs, the association was strongest with rheumatoid diseases (OR 2.6, 95% CI 1.3-4.9). Using lag periods to account for potential sources of bias did not materially change the results. Childhood leukemia, particularly acute lymphoblastic leukemia, was associated with a higher prevalence of AID, independent of T1DM. The findings warrant further investigation on potential shared immune dysregulation or environmental triggers.