The researchers found a link between parental smoking and an increased risk of a common form of cancer in children.
The dangers of passive smoking entails for growing children and unborn babies is well documented, but now researchers are adding a terrifying health risk to the list of genetic changes that are associated with a common form of cancer in children.
The study, published in this edition of Cancer Research, is the first to link smoking by both parents to specific genetic changes in the tumor cells of children with acute lymphocytic leukemia (ALL), Reuters reported.
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“Another way of looking at it is that we see the evidence of the toxic effects of tobacco smoke in the genes of the cell leukemia, a molecular type of forensic pathology,” lead study author Adam Smith, a researcher at the University of California, San Francisco, Helen Diller Family Comprehensive Cancer Center, told Reuters.
“These deletions are not inherited from the parents, but are acquired in the child’s immune cells, so we think it’s more important windows of tobacco exposure during pregnancy and after the birth,” he said.
The researchers examined the data on the pre-treatment tumor samples from 559 ALL patients in a study of leukemia cases in California, Reuters reported. About two-thirds of the tumor samples contained at least one of the eight gene deletions often missing in ALL patients. Deletions were more frequent in children whose mothers had smoked during pregnancy and after the birth, Reuters reported.
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Researchers determined that for every five cigarettes per day during pregnancy, there was a 22 percent increase in the number of deletions, and for each of the five cigarettes per day during lactation, there was a 74 percent increase in the number of deletions. The risk was not exclusive to smoking in mothers, the researchers noted a 7 to 8 percent increase in the number of deletions, when a mother or father smoked five cigarettes per day before conception, Reuters reported.
While the findings noted that boys are more sensitive to the effects of maternal smoking, a limitation of the study was that the researchers do not know when the genetic deletions occurred in comparison with the development of leukemia, Reuters reported. The data are also used on the parents to self-report their smoking habits in the questionnaires.
“The best thing to do to reduce the risk to a minimum is to cut out smoking altogether,” Dr. Marte Reigstad, a researcher at the Olso University Hospital in Norway, who was not involved in the study, told Reuters.
Reuters contributed to this report.