Background: With the exception of Down syndrome the association between congenital anomalies and acute lymphoblastic leukaemia (ALL) is presently unclear. We investigated this association in a population-based case-control study carried out in the province of Québec, CANADA:
Methods: A total of 491 incident cases diagnosed between 1980 and 1993 and aged 0-9 years were included in the study. Healthy controls (n = 491) matched on age, sex, and region of residence at the time of diagnosis were selected from government family allowance files. Using a structured questionnaire and the International Classification of Diseases (Ninth Revision) list of congenital anomalies, presence of an anomaly was determined by interviewing the parents of the study subjects; mothers gave information on anomalies in the study subject, their siblings and her family, whereas fathers provided information on anomalies in their family.
Results: The adjusted risk for ALL was not increased in children who had any anomaly (odds ratio [OR] = 1.07 [95% CI : 0.70-1.65]) whereas compared to control siblings, case siblings had a higher risk of anomalies (OR = 1.54, 95% CI : 0.99- 2.42). This increase was likely due to excesses in anomalies of the heart (OR = 2.49, 95% CI : 1.23-5.04). Risk for ALL was elevated in children with a history of a congenital anomaly in their mother (OR = 1.61, 95% CI : 0.80-3.22) or her family (OR = 1.45, 95% CI : 0.94-2.25).
Conclusions: Although based on small numbers for specific anomalies, these findings suggest that congenital anomalies are more prevalent in siblings and maternal family of ALL cases than in controls.