We evaluated the effect: of smoking on the risk of cervical dysplasia
in a large case-control study, obtaining smoking information from a ma
il questionnaire. We observed higher risks with increasing numbers of
cigarettes smoked, but not with longer duration of smoking. The risk f
or ex-smokers was between those of current smokers and nonsmokers and
was lower for women who had stopped more than 10 years ago than for th
ose who had quit more recently. Starting to smoke at an early age did
not increase the risk of cervical dysplasia.