Cigarette smoke contains dozens of well-established human carcinogens and it is known to increase the risk of various adult cancers including myeloid leukemia. Likewise, parental cigarette smoking may also increase the risk of childhood leukemia.
Parental Smoking and Childhood Leukemia
CIRCLE Dirctor, Dr. Catherine Metayer, and her colleague, Dr. Jeffrey Chang, have evaluated the risk of childhood leukemia associated with parental smoking in the California Childhood Leukemia Study. Their study included 902 children with leukemia and 1139 control children without leukemia. Parental cigarette smoking histories were obtained via interviews, primarily with the biological mother. The study found that a child whose father smoked before conception was at an increased risk of leukemia compared to a child with a nonsmoking father. The risk of leukemia was greatest when preconception paternal smoking was combined with a child’s exposure to passive smoking after birth. Specific molecular subtypes of leukemia were associated with parental smoking. Interestingly, maternal smoking during pregnancy was not associated with childhood leukemia risk in this study. It is challenging to obtain accurate histories of maternal smoking during pregnancy using interviews, because mothers may have trouble remembering their past smoking habits or they may be reluctant to discuss their smoking habits during pregnancy. Moreover, maternal smoking causes other negative birth outcomes, which obscure our ability to measure leukemia risk. Both of these factors could help explain why we did not observe an association between maternal smoking during pregnancy and childhood leukemia. The full article is available here.
Parental Smoking in the Childhood Leukemia International Consortium
The Childhood Leukemia International Consortium strengthened the evidence of a modest association between paternal smoking and the second-most common subtype of childhood leukemia — acute myeloid leukemia (AML) — using a pooled analysis. The study found dose-response relationships, meaning that leukemia risk increased with an increasing number of cigarettes smoked. No associations were observed with maternal smoking any time before or after birth.