Parental cigarette smoking and the risk of acute leukemia in children

BACKGROUND. Studies of the relation between parental smoking and childhood leukemia have produced inconsistent results. In the largest case-control st udies of childhood acute lymphoblastic leukemia (ALL) and acute myeloid leu kemia (AML) conducted to date, the authors evaluated leukemia risk relative to parental self-report of cigarette smoking. METHODS. In telephone interviews in which a structured questionnaire was us ed, parents of 1842 ALL patients, 517 AML patients, and their matched contr ols were asked about their cigarette smoking habits before, during, and aft er the pregnancy with the index child. Risk of leukemia was examined by his tologic type, age of the child at diagnosis, immunophenotype (for ALL), and French-American-British morphology group (for AML). RESULTS. The risk of ALL was not associated with the father's ever having s moked (odds ratio [OR] = 1.04, 95% confidence interval [CI] 0.90-1.20) or t he mother's ever having smoked (OR = 1.04, 95% CI 0.91-1.19). Similarly no significant risk of AML was observed for paternal (OR = 0.88, 95% CI 0.67-1 .16) or maternal smoking (OR = 0.95, 95% CI 0.74-1.22). The relative risk o f leukemia was not significantly different from the null for parental smoki ng in any time period during or around the index pregnancy, nor was it rela ted to the number of cigarettes, the number of years of smoking, or the num ber of pack-years. A small number of sporadic, statistically significant as sociations were found, but overall there appeared to be no association betw een parental cigarette smoking and ALL or AML, or any subgroup of leukemia. CONCLUSIONS. Parenteral smoking while pregnant or exposure to cigarette smo ke shortly after birth is unlikely to contribute substantially to the risk of childhood leukemia in North America. Cancer 1999;85:1380-8. (C) 1999 Ame rican Cancer Society.