Use of oral contraceptives and risk of invasive cervical cancer in previously screened women.

Within the context of a larger hospital-based case-control study carried out to assess the efficacy of cervical cancer screening, the possible association between oral contraceptives and risk of invasive cervical cancer has been studied as well. Because in the GDR cytological screening is an integral part of the gynaecological basic care, only a few women reported oral contraceptive use but had no Pap-smears in that study. Thus, the analysis was confined to those 129 cases and 275 controls who had at least one screening Pap-smear in their history and were below the age 55. The significantly increased relative risks for users decreased after adjustment for factors of sexual behaviour and interval since last Pap-smear but remained statistically significant or at borderline significance for some categories of usage. This concerns, in particular, long-term use (7+ years) and early onset of use (less than or equal to 24 years) with relative risks of 1.8 and 3.0, respectively.