Patterns of infection and day care utilization and risk of childhood acutelymphoblastic leukaemia

To investigate ii decreased exposure to common childhood infections is asso ciated with risk of childhood acute lymphoblastic leukaemia (ALL) we conduc ted a case-control study of 1842 newly diagnosed and immunophenotypically d efined cases of ALL under age 15, and 1986 matched controls in the US. Data regarding day care, sibship size and common childhood infections were obta ined through parental interviews. Data were analysed stratified by leukaemi a lineage and separately for 'common' childhood ALL (age 2-5 years, CD19, C D10-positive). Neither attendance at day care nor time at day care was asso ciated with risk of ALL overall or 'common' ALL. Ear infections during infa ncy 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 tear infections). these data do not support the hypothesis that a decrease in the occurrence of common childhood infection increases risk o f ALL. (C) 2000 Cancer Research Campaign.