Courtesy of the Journal of the National Cancer Institute:
“A large prospective cohort study of more than 76,000 women confirmed a strong association between cigarette smoking and lung cancer but found no link between the disease and secondhand smoke.
“The fact that passive smoking may not be strongly associated with lung cancer points to a need to find other risk factors for the disease [in nonsmokers],” said Ange Wang, the Stanford University medical student who presented the study at the June 2013 meeting of the American Society of
Clinical Oncology in Chicago.
The incidence of lung cancer was 13 times higher in current smokers and four times higher in former smokers than in never-smokers, and the relationship for both current and former smokers depended on level of exposure. However, among women who had never smoked, exposure to passive
smoking overall, and to most categories of passive smoking, did not statistically significantly increase lung cancer risk.