- (1) International Agency For Research On Cancer, grid.17703.32
- (2) Centre for research in epidemiology and population health, grid.463845.8
- (3) Institut Gustave Roussy, grid.14925.3b
- (4) University of Paris-Sud, grid.5842.b
- (5) Cancer Council Victoria, grid.3263.4
- (6) University of Melbourne, grid.1008.9
- (7) Aarhus University, grid.7048.b, AU
- (8) Diet, Genes, and Environment Unit, Danish Cancer Society Research Center, Copenhagen, Denmark.
- (9) German Cancer Research Center, grid.7497.d
- (10) Umeå University, grid.12650.30
- (11) German Institute of Human Nutrition, grid.418213.d
- (12) National and Kapodistrian University of Athens, grid.5216.0
- (13) Academy of Athens, grid.417593.d
- (14) Hellenic Health Foundation, grid.424637.0
- (15) Harvard University, grid.38142.3c
- (16) Istituto per lo Studio e la Prevenzione Oncologica, grid.417623.5
- (17) Fondazione IRCCS Istituto Nazionale dei Tumori, grid.417893.0
- (18) Cancer Registry and Histopathology Unit, "Civic M.P.Arezzo" Hospital, ASP Ragusa, Italy;
- (19) Human Genetics Foundation, grid.428948.b
- (20) Imperial College London, grid.7445.2
- (21) University of Naples Federico II, grid.4691.a
- (22) National Institute for Public Health and the Environment, grid.31147.30
- (23) University Medical Center Utrecht, grid.7692.a
- (24) The Arctic University of Norway, grid.10919.30
- (25) Cancer Registry of Norway, grid.418941.1
- (26) Folkhälsans Forskningscentrum, grid.428673.c
- (27) Karolinska Institute, grid.4714.6
- (28) Public Health Directorate, Asturias, Spain.
- (29) Department of Epidemiology, Murcia Regional Health Authority, Murcia, Spain.
- (30) CIBER Epidemiology and Public Health CIBERESP, Madrid, Spain.
- (31) Instituto de Salud Pública de Navarra, grid.419126.9
- (32) Andalusian School of Public Health, grid.413740.5
- (33) Instituto de Investigación Biosanitaria, grid.507088.2
- (34) Catalan Institute of Oncology, grid.418701.b
- (35) Public Health Division of Gipuzkoa, Gipuzkoa, Spain.
- (36) Lund University, grid.4514.4
- (37) University of Cambridge, grid.5335.0
- (38) University of Oxford, grid.4991.5
Alcohol intake has been associated to breast cancer in pre and postmenopausal women; however results are inconclusive regarding tumor hormonal receptor status, and potential modifying factors like age at start drinking. Therefore, we investigated the relation between alcohol intake and the risk of breast cancer using prospective observational data from the European Prospective Investigation into Cancer and Nutrition (EPIC). Up to 334,850 women, aged 35-70 years at baseline, were recruited in ten European countries and followed up an average of 11 years. Alcohol intake at baseline and average lifetime alcohol intake were calculated from country-specific dietary and lifestyle questionnaires. The study outcomes were the Hazard ratios (HR) of developing breast cancer according to hormonal receptor status. During 3,670,439 person-years, 11,576 incident breast cancer cases were diagnosed. Alcohol intake was significantly related to breast cancer risk, for each 10 g/day increase in alcohol intake the HR increased by 4.2% (95% CI: 2.7-5.8%). Taking 0 to 5 g/day as reference, alcohol intake of >5 to 15 g/day was related to a 5.9% increase in breast cancer risk (95% CI: 1-11%). Significant increasing trends were observed between alcohol intake and ER+/PR+, ER-/PR-, HER2- and ER-/PR-HER2- tumors. Breast cancer risk was stronger among women who started drinking prior to first full-time pregnancy. Overall, our results confirm the association between alcohol intake and both hormone receptor positive and hormone receptor negative breast tumors, suggesting that timing of exposure to alcohol drinking may affect the risk. Therefore, women should be advised to control their alcohol consumption.