Environmental, maternal, and reproductive risk factors for childhood acute lymphoblastic leukemia in Egypt: a case-control study

BACKGROUND: Acute lymphocytic leukemia (ALL) is the most common pediatric cancer. The exact cause is not known in most cases, but past epidemiological research has suggested a number of potential risk factors. This study evaluated associations between environmental and parental factors and the risk for ALL in Egyptian children to gain insight into risk factors in this developing country. Methods: We conducted a case-control design from May 2009 to February 2012. Cases were recruited from Children’s Cancer Hospital, Egypt (CCHE). Healthy controls were randomly selected from the general population to frequency-match the cumulative group of cases by sex, age groups (<1; 1 – 5; >5 – 10; >10 years) and region of residence (Cairo metropolitan region, Nile Delta region (North), and Upper Egypt (South)). Mothers provided answers to an administered questionnaire about their environmental exposures and health history including those of the father. Odds ratios (ORs) and 95 % confidence intervals (CI) were calculated using logistic regression with adjustment for covariates. RESULTS: Two hundred ninety nine ALL cases and 351 population-based controls frequency-matched for age group, gender and location were recruited. The risk of ALL was increased with the mother’s use of medications for ovulation induction (OR(adj) = 2.5, 95 % CI =1.2 –5.1) and to a lesser extend with her age (OR(adj) = 1.8, 95 % CI = 1.1 – 2.8, for mothers ≥ 30 years old). Delivering the child by Cesarean section, was also associated with increased risk (OR(adj) = 2.01, 95 % CI =1.24–2.81). CONCLUSIONS: In Egypt, the risk for childhood ALL appears to be associated with older maternal age, and certain maternal reproductive factors.