Time since last use of oral contraceptives and risk of invasive cervical cancer

The time-risk relationship for the association between cervical cancer and oral contraceptives (OC) was examined using data on 592 cases of invasive cervical cancer aged 60 years or less and 616 controls with acute, non-gynaecological, non-hormone-related, non-neoplastic diseases. A total of 125 cases and 114 controls reported ever using OC and the multivariate odds ratio (OR) for ever versus never users was 1.21 (95% confidence interval (CI) 0.82-1.74). The risk of invasive cervical cancer was above unity in current users (OR 1.23) and in women who had stopped OC use less than 10 years before diagnosis, but not in those who had stopped their OC use greater than or equal to 10 years before (OR 0.85). Similarly, the OR was less for women who had started OC use 15 years or more previously than for more recent users. These data suggest that OCs may have a late stage (promoter) effect on cervical carcinogenesis and thus have public health implications, since the incidence of invasive cervical cancers is low at young ages, when OC use is more common and increases during middle age. The absence of a persisting risk is therefore of interest both for assessing individual risk and for its public health implications. (C) 1998 Elsevier Science Ltd. All rights reserved