The authors conducted a case-control study in Mexico City between September 1990 and December 1992 to determine whether a dose-response relation could be observed between duration of lactation and the risk of breast cancer.
Cases, women aged 20-75 years, were identified through six hospitals in Mexico City (n=349) and were interviewed to obtain data on risk factors for breast cancer, including a detailed history of lactation.
Controls (n=1,005) were selected from the general population using the Mexican national sampling frame.
Parous women who had ever lactated had a reduction in breast cancer risk (age-adjusted odds ratio (OR)=0.39,95% confidence interval (Cl) 0.25-0.62).
A small decreasing trend of breast cancer risk in relation to duration of lactation (p<0.001) was observed.
Compared with parous women who had never breast-fed, women who had breast-fed for 12-24 months had an age-adjusted odds ratio of 0.47 (95% CI 0.27-0.83).
A stronger protective effect was observed with lactation duration for the first live birth among pre-and postmenopausal women (for 4-12 months of lactation, OR=0.56 (95 percent CI 0.32-0.96) and OR=0.48 (95 percent CI 0.29-0.81) in pre-and postmenopausal women, respectively).
Adjusting for potentially confounding factors modified these results only slightly.
The declining trend in fertility and lactation among Mexican women could lead to a major epidemic of breast cancer such as that observed in Western countries.
Mots-clés Pascal : Tumeur maligne, Glande mammaire, Epidémiologie, Allaitement, Lactation, Durée, Femme, Homme, Mexique, Amérique Centrale, Amérique, Glande mammaire pathologie
Mots-clés Pascal anglais : Malignant tumor, Mammary gland, Epidemiology, Breast feeding, Lactation, Duration, Woman, Human, Mexico, Central America, America, Mammary gland diseases
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Inist-CNRS - Institut de l'Information Scientifique et Technique
Cote : 96-0182796
Code Inist : 002B20E02. Création : 199608.