Active and passive smoking in relation to lung cancer incidence in the Women’s Health Initiative Observational Study prospective cohort

Using a data set of over 76,000 women from the Women's Health Initiative Observational Study, the effects of active and passive smoking on cancer were evaluated.  Lung cancer incidence was highest among active smokers (HR 13.44) and was also high among prior smokers (HR 4.20).  A prolonged exposure (>30 yr) to passive smoking in the household also increased the risk of lung cancer (HR 1.61).