Pooled analysis of 3 european case-control studies: I. Reproductive factors and risk of epithelial ovarian cancer

Authors

  • Eva Negri,

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

    1. Department of Hygiene and Epidemiology, Athens Medical School, Goudi, Athens 11527, Greece
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  • Margaret Booth,

    1. Epiderniological Monitoring Unit, London School of Hygiene and Tropical Medicine, Keppel Street (Gower Street), London WClE 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 Lausanne, Switzerland
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  • Fabio Parazzini,

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

    1. Imperial Cancer Research Fund, Epidemiology and Clinical Trials Unit, Radcliffe Infirmary, Oxjord OX2 6HE, UK
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  • Peter Boyle,

    1. The SEARCH Programme, Unit of Analytical Epidemiology, International Agency for Research on Cancer, 150 Cours Albert-Thomas, 69372 Lyon Cedex 08, France
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  • Dimitrios Trichopoulos

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

The role of reproductive factors in the aetiology of epithelial ovarian cancer has been re-assessed in a meta-analysis of 3 hospital-based case-control studies conducted in Europe (i.e. Italy, the United Kingdom and Greece), providing a total dataset of 1,140 cases and 2,724 controls. Multiple logistic regression models were used to obtain relative risk (RR) estimates adjusted for study centre, age, socio-cultural indicators, age at menopause, and oral contraceptive use. The risk decreased with increasing number of births and the trend in risk was significant (Xmath image = 7.50, p < 0.01). In comparison to nulliparous women, those who reported 4 or more births had a 40% reduction in risk of ovarian cancer (RR = 0.6, 95% confidence interval, CI: 0.4-0.8). An RR estimate of 1.4 (95% CI: 1.1-1.7) was found, overall, for age of 35 or more at first birth compared to age of 25 or less at first birth. In each stratum and overall, nulliparous women did not appear to be at increased risk compared to those who delayed birth of their first child until age 35 or more. In each study, as well as in the overall dataset, an inverse association between number of abortions and ovarian cancer risk emerged. Overall, the inverse relationship was highly significant, RR estimates for 1 and 2 or more abortions, as compared to none, being 0.9 (95% CI: 0.8 and 1.1) and 0.7 (95% CI: 0.60.9) respectively. The effects of parity, age at first birth and number of abortions emerged consistently in various strata of study centre and age.

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