title: Attributable risks for breast cancer in Italy: education, family history and reproductive and hormonal factors.
abstract: The percent population attributable risk (AR) for breast cancer was estimated in relation to education, family history of the disease and some reproductive and hormonal factors, using data from a case-control study conducted between June 1991 and February 1994 in 6 Italian centres on 2,569 histologically confirmed incident breast cancer cases and 2,588 controls, admitted to hospital for a wide range of acute, non-neoplastic, non-hormone-related diseases. On the basis of multivariate odds ratios, a high level of education accounted for 20% of cases, elevated age at first birth and nulliparity for 38% and a family history of breast cancer in first-degree relatives for 7%. Education and nulliparity and age at first birth together explained 47% of all breast cancer cases, and the combination of these 2 factors plus a family history of the disease explained 50% of cases. In pre-menopausal women a high level of education accounted for 31% of all breast cancer cases, older age at first birth for 44% and the combination of the 2 factors for 49%. In post-menopausal women the corresponding values were 13%, 31% and 42%; further addition of risk associated with family history of the disease explained 52% of pre-menopausal cases. In post-menopausal women older age at menopause and the use of hormone replacement therapy accounted for 15% and 2% of breast cancer cases, respectively. The combination of risks associated with a high level of education, old age at first birth and nulliparity and older age at menopause accounted for 51% of cases; further inclusion of risk associated with use of hormone replacement therapy explained 52%, and the AR resulting from these 4 risk factors combined plus a family history of breast cancer was 56%. Thus, a few selected and well-identified risk factors explain about one-half the breast cancer cases in this Italian population.
authors.affiliation: Istituto de Richerche Farmacologiche Mario Negri, Milan, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Tavani
authors.forename: C
authors.initials: C
authors.lastname: Braga
authors.forename: C
authors.initials: C
authors.lastname: La Vecchia
authors.forename: E
authors.initials: E
authors.lastname: Negri
authors.forename: A
authors.initials: A
authors.lastname: Russo
authors.forename: S
authors.initials: S
authors.lastname: Franceschi
mesh_terms: D000367:Age Factors; D001943:Breast Neoplasms / Q000453:epidemiology* / Q000235:genetics; D016022:Case-Control Studies; D004522:Educational Status; D015914:Estrogen Replacement Therapy / Q000009:adverse effects; D005260:Female; D012739:Gonadal Steroid Hormones; D006801:Humans; D007558:Italy / Q000453:epidemiology; D008593:Menopause; D016017:Odds Ratio; D017584:Reproductive History; D012306:Risk
chemical_list: D012739:Gonadal Steroid Hormones