%0 Journal Article
%T Breastfeeding and the risk of breast cancer in BRCA1 and BRCA2 mutation carriers
%A Joanne Kotsopoulos
%A Jan Lubinski
%A Leonardo Salmena
%A Henry T Lynch
%A Charmaine Kim-Sing
%A William D Foulkes
%A Parviz Ghadirian
%A Susan L Neuhausen
%A Rochelle Demsky
%A Nadine Tung
%A Peter Ainsworth
%A Leigha Senter
%A Andrea Eisen
%A Charis Eng
%A Christian Singer
%A Ophira Ginsburg
%A Joanne Blum
%A Tomasz Huzarski
%A Aletta Poll
%A Ping Sun
%A Steven A Narod
%A the Hereditary Breast Cancer Clinical Study Group
%J Breast Cancer Research
%D 2012
%I BioMed Central
%R 10.1186/bcr3138
%X We conducted a case-control study of 1,665 pairs of women with a deleterious mutation in either BRCA1 (n = 1,243 pairs) or BRCA2 (n = 422 pairs). Breast cancer cases and unaffected controls were matched on year of birth, mutation status, country of residence and parity. Information about reproductive factors, including breastfeeding for each live birth, was collected from a routinely administered questionnaire. Conditional logistic regression was used to estimate the association between ever having breastfed, as well as total duration of breastfeeding, and the risk of breast cancer.Among BRCA1 mutation carriers, breastfeeding for at least one year was associated with a 32% reduction in risk (OR = 0.68; 95% CI 0.52 to 0.91; P = 0.008); breastfeeding for two or more years conferred a greater reduction in risk (OR = 0.51; 95% CI 0.35 to 0.74). Among BRCA2 mutation carriers, there was no significant association between breastfeeding for at least one year and breast cancer risk (OR = 0.83; 95% CI 0.53 to 1.31; P = 0.43).These data extend our previous findings that breastfeeding protects against BRCA1-, but not BRCA2-associated breast cancer. BRCA mutation carriers should be advised of the benefit of breastfeeding in terms of reducing breast cancer risk.In the general population, reproductive factors, including late age at menarche, parity and breastfeeding, have been shown to protect against the development of breast cancer [1-3]. Various proposed mechanisms include reducing lifetime exposure to ovarian hormones, reducing the cumulative number of ovulatory cycles and differentiation of the breast lobules [4,5]. We and others have evaluated the impact of reproductive factors in the etiology of BRCA-associated breast cancer, although the results are conflicting and vary by BRCA1 or BRCA2 mutation [6-8]. With respect to breastfeeding and breast cancer risk in BRCA1 mutation carriers, two previous studies reported no relationship [9,10] and three studies reported a protectiv
%U http://breast-cancer-research.com/content/14/2/R42