Pooled analysis of 3 european case-control studies of epithelial ovarian cancer: III. Oral contraceptive use

Authors

  • Silvia Franceschi,

    Corresponding author
    1. Epidemiology Unit, Aviano Cancer Center, Via Pedemontana Occ., 33081 Aviano (PN), Italy
    2. European Cancer Prevention Organization (ECP), Hormone, Sexual Factors and Cancer, Brussels, Belgium
    • Epidemiology Unit, Aviano Cancer Center, Via Pedemontana Occ., 33081 Aviano (PN), Italy
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  • Fabio Parazzini,

    1. “Mario Negri” Institute for Pharmacological Research, Via Eritrea 62, 20157 Milan, Italy
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  • Eva Negri,

    1. “Mario Negri” Institute for Pharmacological Research, Via Eritrea 62, 20157 Milan, Italy
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  • Margaret Booth,

    1. Epidemiological Monitoring Unit, London School of Hygiene and Tropical Medicine, Keppel Street (Gower Street), London WC1E 7HT, UK
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  • Carlo La Vecchia,

    1. “Mario Negri” Institute for Pharmacological Research, Via Eritrea 62, 20157 Milan, Italy
    2. Institute of Social and Preventive Medecine, University of Lausanne, Bugnon 17, 1005 Lawanne, Switzerland
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  • Valerie Beral,

    1. Imperial Cancer Research Fund, Epidemiology and Clinical Trials Unit, Radcliffe Infirmary, Oxford OX2 6HE, UK
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  • Anastasia Tzonou,

    1. Department of Hygiene and Epidemiology, Athens Medical School, Goudi, Athens 11527, Greece
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  • Dimitrios Trichopoulos

    1. Department of Epidemiology, Harvard School of Public Health, 677 Huntington Avenue, Boston, MA 02115, USA
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Abstract

The relationship between use of oral contraceptives (OCs) and other contraceptive methods and the risk of ovarian cancer was examined in a combined analysis of 3 hospital-based case-control studies conducted in Italy, the United Kingdom, and Greece, for a total of 971 ovarian cancer cases and 2,258 controls under age 65. Compared with never-users, the combined multivariate relative risk (RR) for ever-users was 0.6 (95% confidence interval, CI = 0.4-0.8) and the estimates were consistent in the 3 datasets. The protection was also similar across strata of age and parity. Considering various measures of OC use, available in the Italian and British data-sets only, the protection conveyed on ovarian cancer risk increased with the duration of use and persisted in the medium-long period: the RR in women reporting their last OC use ≧15 years prior to diagnosis was 0.5 (95% CI = 0.2-1.0). The risks in ever-users were appreciably lower in those women who reported their first OC use before 25 years of age (RR = 0.3 for first use before age 25. 0.8 for first use at age 25-34 and 0.7 at 35 years or after). Such findings emerged similarly from Italian and British data. This combined analysis, besides offering further quantitative estimates of the protective effects of OCs on ovarian cancer risk in European populations, provides useful insights into the time pattern of the relationship between OC use and ovarian carcinogenesis, suggesting that the protection persists for 15 years or more after cessation of use and may be larger for use at younger age.

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