Children who grow up in homes in which both parents smoke are twice as likely to develop lung cancer in adulthood as are children reared in tobacco-free homes, a new study suggests.
A report on the study, which the authors say is the first to show a relationship between childhood exposure to tobacco and adult lung cancer, appeared in the Sept. 6 issue of The New England Journal of Medicine.
The study, conducted by 10 researchers from six institutions, suggests that nearly one-fifth of the lung cancers among nonsmokers “can be attributed to high levels of exposure to cigarette smoke during childhood and adolescence.”
More than 150,000 new cases of lung cancer are diagnosed each year. The vast majority of these cancers are diagnosed in current or former smokers.
To examine the link between exposure to passive smoking and lung cancer, the researchers matched 191 nonsmokers who had developed lung cancer as adults between 1982 and 1984 with 191 randomly chosen, healthy nonsmokers.
Nonsmokers who had been exposed to the equivalent of two smoking parents for 12 years or more were twice as likely to develop lung cancer as were nonsmokers who were raised by nonsmoking parents. Nonsmokers whose parents had smoked for a shorter period of time, or who were married to a spouse who smoked, were not at greater risk of developing the disease, the study found.
Researchers believe that children may be more susceptible to a number of environmental hazards, such as tobacco and asbestos, because their lungs are still developing and because, proportionately, their lungs work harder than those of adults.
Previous studies have found that the children of parents who smoke are more likely to develop respiratory problems, the researchers said.
“This type of susceptibility might initiate changes that eventually lead to lung cancer when the exposed children become adults,” the authors wrote, “but we know of no specific mechanism that would explain our findings.”
