Multiple births, sex of children and subsequent breast-cancer risk for the mothers : a prospective study in Norway.
Endocrinological changes occurring during pregnancy may influence the subsequent cancer risk of the mother.
Further, the endocrinological milieu may differ according to different birth characteristics.
In the present study possible relations between multiple births, sex of children and breast-cancer risk were examined in a population-based, prospective study of 802,269 parous Norwegian women aged 20-56 years.
A total of 4,782 women were diagnosed with breast cancer during follow-up.
Of these, 97 had ever experienced a multiple birth.
We found a slightly lower risk of breast cancer among women ever having had a multiple birth than among women with singletons only (IRR=0.89,95% CI=0.73-1.09).
The reduction in risk was mainly observed among women with a multiple last birth.
Further, the reduction in risk seemed to diminish with increasing parity, and among women with 4 or more full-term pregnancies, ever having had a multiple birth was associated with an elevated risk (IRR=1.48,95% CI=0.97-2.25).
The sex of the first or last child did not affect the subsequent breast-cancer risk.
Further, we found no associations with the sex distribution among all children or in multiple births, despite a tendency toward a reduced risk among women with several daughters only.
Mots-clés Pascal : Tumeur maligne, Glande mammaire, Facteur risque, Epidémiologie, Multiparité, Sexe, Descendance, Prospective, Etude longitudinale, Norvège, Europe, Homme, Glande mammaire pathologie
Mots-clés Pascal anglais : Malignant tumor, Mammary gland, Risk factor, Epidemiology, Multiparity, Sex, Progeny, Prospective, Follow up study, Norway, Europe, Human, Mammary gland diseases
Notice produite par :
Inist-CNRS - Institut de l'Information Scientifique et Technique
Cote : 95-0166203
Code Inist : 002B20E02. Création : 09/06/1995.