title: Oral contraceptive use and malignancies of the genital tract. Results from the Royal College of General Practitioners' Oral Contraception Study.
abstract: Of 47,000 women followed since 1968, those who had used oral contraceptives (ever-users) had a significantly higher incidence rate of cervical cancer than never-users. After standardisation of rates by age, parity, smoking, social class, number of previously normal cervical smears, and history of sexually transmitted disease, the excess was 41 per 100,000 woman-years for carcinoma-in-situ and 8 per 100,000 woman-years for invasive cervical cancer. Incidence increased with increasing duration of use: the standardised incidence rate for cervical cancer in women who had taken the pill for more than 10 years was four times than in never-users. Ever-users had a lower incidence of other uterine cancers (deficit 5 per 100,000 woman-years); a lower incidence of ovarian cancer was also found (deficit 4 per 100,000), but was not statistically significant. Overall, ever-users had an excess incidence for genital tract cancers 37 per 100,000 woman-years. This excess was mainly from carcinoma-in-situ of the cervix; the excess incidence of invasive cervical cancer was offset by the deficits in other uterine and ovarian cancers. Standardised mortality rates from genital cancer were similar in ever-users and never-users. Of relevance to clinical practice is the substantially different distribution of primary cancer sites: cervical cancer accounted for 75% of the invasive genital cancers and 74% of deaths from genital cancer in ever-users, but only 31% of the invasive cancers and 30% of deaths in never-users.
mesh_terms: D000293:Adolescent; D000328:Adult; D002278:Carcinoma in Situ / Q000453:epidemiology / Q000401:mortality; D003276:Contraceptives, Oral; D004739:England; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008875:Middle Aged; D010051:Ovarian Neoplasms / Q000453:epidemiology* / Q000401:mortality; D012494:Sampling Studies; D013997:Time Factors; D002583:Uterine Cervical Neoplasms / Q000453:epidemiology / Q000401:mortality; D014594:Uterine Neoplasms / Q000453:epidemiology* / Q000401:mortality; D014852:Wales
chemical_list: D003276:Contraceptives, Oral