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Oral contraceptives and breast cancer: a cooperative Italian study.

Abstract

The relationship between oral contraceptives (OC) and breast-cancer risk was analysed using data from a case-control study conducted between June 1991 and February 1994 in 6 Italian centres on 1,991 patients below age 65 with histologically confirmed incident breast cancer and 1,899 controls admitted to hospital for a wide range of acute, non-neoplastic, non-hormone-related diseases. "Ever OC use" was reported by 18% of cases versus 14% of controls, corresponding to a multivariate odds ratio (OR) of 1.1 (95%) confidence interval, Cl 0.9 to 1.4). The ORs were 1.3 for use lasting < 1 year, 1.1 for 1 to 4 years, 0.9 for 5 to 8 years, and 1.2 for over 8 years. With reference to age at first use, there was some indication that the OR was elevated in women who had started use before age 30, but not in those starting at a later age. With reference to time since last OC use, the OR was above unity for women who had stopped for less than 10 years (1.6 for 1 to 4 years; 1.7 for 5 to 9 years), but the OR declined to unity for women who had stopped OC use for 10 years or longer. The OR for women who had stopped OC use for less than 10 years was consistently elevated across strata of selected covariates, and was directly related to the duration of use (OR 1.3 for < 5 years, 1.7, for > or = 5 years). In contrast, the OR was 0.6, for use lasting > or = 5 years in women who had stopped for 10 years or more. The elevated OR for women who had recently stopped OC use, together with the absence of association (or the suggestion of some protection) for those who had stopped for 10 years or more is consistent with the pattern of breast-cancer risk observed after a full-term pregnancy, and provides important reassurance on a public health level on the long-term impact of OCs on breast carcinogenesis.

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  • Authors+Show Affiliations

    ,

    Istituto di Ricerche Farmacologiche, Mario Negri, Milan, Italy.

    , , , , , , , ,

    Source

    International journal of cancer 60:2 1995 Jan 17 pg 163-7

    MeSH

    Adult
    Breast Neoplasms
    Case-Control Studies
    Contraceptives, Oral
    Female
    Humans
    Middle Aged
    Risk

    Pub Type(s)

    Journal Article

    Language

    eng

    PubMed ID

    7829209

    Citation

    La Vecchia, C, et al. "Oral Contraceptives and Breast Cancer: a Cooperative Italian Study." International Journal of Cancer, vol. 60, no. 2, 1995, pp. 163-7.
    La Vecchia C, Negri E, Franceschi S, et al. Oral contraceptives and breast cancer: a cooperative Italian study. Int J Cancer. 1995;60(2):163-7.
    La Vecchia, C., Negri, E., Franceschi, S., Talamini, R., Amadori, D., Filiberti, R., ... Parazzini, F. (1995). Oral contraceptives and breast cancer: a cooperative Italian study. International Journal of Cancer, 60(2), pp. 163-7.
    La Vecchia C, et al. Oral Contraceptives and Breast Cancer: a Cooperative Italian Study. Int J Cancer. 1995 Jan 17;60(2):163-7. PubMed PMID: 7829209.
    * Article titles in AMA citation format should be in sentence-case
    TY - JOUR T1 - Oral contraceptives and breast cancer: a cooperative Italian study. A1 - La Vecchia,C, AU - Negri,E, AU - Franceschi,S, AU - Talamini,R, AU - Amadori,D, AU - Filiberti,R, AU - Conti,E, AU - Montella,M, AU - Veronesi,A, AU - Parazzini,F, PY - 1995/1/17/pubmed PY - 1995/1/17/medline PY - 1995/1/17/entrez KW - Age Factors KW - Breast Cancer--etiology KW - Cancer KW - Case Control Studies KW - Contraception KW - Contraceptive Methods KW - Demographic Factors KW - Developed Countries KW - Diseases KW - Europe KW - Family Planning KW - Italy KW - Mediterranean Countries KW - Neoplasms KW - Oral Contraceptives KW - Population KW - Population Characteristics KW - Population Dynamics KW - Research Report KW - Southern Europe KW - Studies KW - Time Factors SP - 163 EP - 7 JF - International journal of cancer JO - Int. J. Cancer VL - 60 IS - 2 N2 - The relationship between oral contraceptives (OC) and breast-cancer risk was analysed using data from a case-control study conducted between June 1991 and February 1994 in 6 Italian centres on 1,991 patients below age 65 with histologically confirmed incident breast cancer and 1,899 controls admitted to hospital for a wide range of acute, non-neoplastic, non-hormone-related diseases. "Ever OC use" was reported by 18% of cases versus 14% of controls, corresponding to a multivariate odds ratio (OR) of 1.1 (95%) confidence interval, Cl 0.9 to 1.4). The ORs were 1.3 for use lasting < 1 year, 1.1 for 1 to 4 years, 0.9 for 5 to 8 years, and 1.2 for over 8 years. With reference to age at first use, there was some indication that the OR was elevated in women who had started use before age 30, but not in those starting at a later age. With reference to time since last OC use, the OR was above unity for women who had stopped for less than 10 years (1.6 for 1 to 4 years; 1.7 for 5 to 9 years), but the OR declined to unity for women who had stopped OC use for 10 years or longer. The OR for women who had stopped OC use for less than 10 years was consistently elevated across strata of selected covariates, and was directly related to the duration of use (OR 1.3 for < 5 years, 1.7, for > or = 5 years). In contrast, the OR was 0.6, for use lasting > or = 5 years in women who had stopped for 10 years or more. The elevated OR for women who had recently stopped OC use, together with the absence of association (or the suggestion of some protection) for those who had stopped for 10 years or more is consistent with the pattern of breast-cancer risk observed after a full-term pregnancy, and provides important reassurance on a public health level on the long-term impact of OCs on breast carcinogenesis. SN - 0020-7136 UR - https://www.unboundmedicine.com/medline/citation/7829209/Oral_contraceptives_and_breast_cancer:_a_cooperative_Italian_study_ L2 - https://onlinelibrary.wiley.com/resolve/openurl?genre=article&amp;sid=nlm:pubmed&amp;issn=0020-7136&amp;date=1995&amp;volume=60&amp;issue=2&amp;spage=163 DB - PRIME DP - Unbound Medicine ER -