@article{3093721,
    title = "The intrauterine origin of male breast cancer: a birth order study in
Denmark",
    author = "Sorensen, HT and Olsen, ML and Mellemkjaer, L and Lagiou, P and Olsen, and JH and Olsen, J",
    journal = "European Journal of Cancer Prevention: The Official Journal of the European Cancer Prevention Organisation (ECP)",
    year = "2005",
    volume = "14",
    number = "2",
    pages = "185-186",
    publisher = "Lippincott, Williams & Wilkins",
    issn = "0959-8278",
    doi = "10.1097/00008469-200504000-00016",
    keywords = "birth order; case-control; in utero; male breast cancer",
    abstract = "First pregnancies are known to have higher oestrogen levels than later
ones and first-born women are at increased breast cancer risk compared
with later-born women. We hypothesized that a birth order effect might
be even more evident in male breast cancer patients, in whom oestrogens
in adult life are generally low. In a population-based study in Denmark
involving 77 male breast cancer patients and 288 population controls,
first-born men compared with later-born men had a relative risk of 1.71
for the disease (95% confidence interval (Cl) 1.00-2.92). This result
is in line with that seen in female breast cancer cases and indicates
that male breast cancer may have roots in the intrauterine life,
oestrogens being a likely mediator. (c) 2005 Lippincott Williams &
Wilkins."
}