Seasonal variations in childhood leukaemia incidence in France, 1990–2014
Menée en France à partir des données du registre national des cancers de l'enfant sur la période 1990-2014, cette étude analyse les variations saisonnières dans l'incidence des leucémies pédiatriques
Background : Several studies have addressed the potential seasonality of childhood acute leukaemia (AL) without conclusive results. Using data from the National Registry of Childhood Cancers over 1990–2014 in mainland France, we investigated the seasonal variations in childhood AL taken together, and lymphoblastic (ALL) and myeloid (AML) leukaemia separately. Methods : Assuming constant variations over 1990–2014, we used a Poisson regression model to evaluate variations in standardized incidence ratios (SIRs) by month of birth or diagnosis. A scan method for temporal cluster detection was used to identify windows of several consecutive months with high or low SIR. The yearly reproducibility of the observed monthly variations was then evaluated. Results : We included 11,528 AL, of which 9493 ALL and 1,843 AML. No seasonal variation was detected for ALL. With a clear seasonal pattern, differences in AML incidence rates were evidenced between January–April and May–December birth periods (SIR = 0.85, 95% CI 0.77–0.94 and SIR = 1.07, 95% CI 1.01–1.14, respectively). AML incidence variations by month of diagnosis were less clear-cut. Conclusion : Based on a large number of cases from a high-quality registry, we did not evidence any seasonality in ALL incidence rates but evidenced seasonal variations in AML incidence rates by month of birth.