Day-care, early common infections and childhood acute leukaemia: a multicentre French case-control study.

We conducted a case-control study to investigate the role of early infections in the aetiology of childhood acute leukaemias. The study included 280 incident cases (240 acute lymphoblastic leukaemia and 40 acute non-lymphoblastic leukaemia) and 288 hospital controls, frequency matched by age, gender, hospital, catchment area of the hospital and ethnic origin. Data were obtained from standardised face-to-face interviews of the mothers. The interviews included questions on early common infections, day-care attendance, breast-feeding, birth order and infantile diseases. Odds ratios were estimated using an unconditional regression model including the stratification variables, parental socio-economic status and perinatal characteristics. Birth order was not associated with childhood leukaemia (acute lymphoblastic or acute non-lymphoblastic). A statistically-significant inverse association was observed between childhood leukaemia and day-care attendance (odds ratio=0.6, 95% Confidence Interval=(0.4-1.0)), repeated early common infections (> or = 4 per year before age two, odds ratio=0.6 (0.4-1.0)), surgical procedures for ear-nose-throat infections before age two (odds ratio=0.5 (0.2-1.0)) and prolonged breast-feeding (> or = 6 months, odds ratio=0.5 (0.2-1.0)). In the multivariate model including day-care attendance, early common infections and breast-feeding, results concerning breast-feeding remained unchanged. A statistically significant interaction between day-care attendance and repeated early common infections was observed. When the interaction was taken into account, the simple effects of day-care and early common infections disappeared (odds ratio=1.1 (0.5-2.3) and odds ratio=0.8 (0.5-1.3), respectively) while the joint effect of day-care attendance and early common infections was negatively associated with childhood leukaemia (odds ratio=0.3 (0.1-0.8)). All the above associations were observed both for acute lymphoblastic leukaemia and acute non-lymphoblastic leukaemia. Our results support Greaves' hypothesis, even though they are not specific of common leukaemia.

Family cancer history and risk of childhood acute leukemia (France).

OBJECTIVE: A case-control study was carried out to investigate the role of a family history of solid tumor or hematologic neoplasm in the etiology of childhood acute leukemia. METHODS: Family cancer history in first- and second-degree relatives was compared in 279 incident cases (242 cases of acute lymphocytic leukemia and 37 of acute myeloid leukemia) and 285 controls. Recruitment was stratified by age, gender, hospital, area of residence, and ethnic origin. Odds ratios (OR) were estimated using an unconditional regression model taking into account the stratification variables, socioeconomic status, and familial structure. RESULTS: A significant association between childhood acute leukemia and a family history of hematologic neoplasm (OR = 2.7, confidence interval (CI) = 1.1-6.9) was found. This association was particularly clear-cut when the cases were restricted to acute myeloid leukemia (OR = 13.3, CI = 2.5-70.9). Childhood acute leukemia was associated with a family history of solid tumor (OR = 1.5, CI = 1.0-2.2), and elevated odds ratios were observed for family history of gastrointestinal cancer and melanoma. Those results are most unlikely to be explained by socioeconomic status and familial structure, which were very similar for the cases and controls. Differential misclassification is also unlikely for the first-degree relatives, even though it is difficult to rule it out for the second-degree relatives' history. CONCLUSION: The present study supports the hypothesis that a family history of cancer may be a risk factor for childhood acute leukemia.