title: Is breast cancer risk associated with alcohol intake before first full-term pregnancy?
abstract: It is plausible that breast tissue is particularly susceptible to carcinogens, including ethanol, between menarche and the first full-term pregnancy ("first pregnancy"). There is some epidemiological evidence that intake before the first pregnancy is more closely associated with risk of breast cancer than is intake thereafter. We examined this association using lifetime alcohol consumption data from a prospective cohort study.
  
  
  
  We calculated usual alcohol intake for age periods 15-19 years and for 10-year period from age 20 to current age (in grams per day) using recalled frequency and quantity of beverage-specific consumption for 13,630 parous women who had their first pregnancy at age 20 years or later, had no cancer history and were aged 40-69 years at enrollment. Cox regression was performed to estimate hazard ratios (HRs) and their 95 % confidence intervals (CIs).
  
  
  
  A total of 651 incident invasive adenocarcinomas of the breast were diagnosed during a mean follow-up of 16.1 years. Alcohol consumption was low overall with only a few drinking ≥40 g/day. Intake before the first pregnancy was markedly lower (mean intake: 2.5 g/day; abstention: 58.8 %) than intake thereafter (mean intake: 6.0 g/day; abstention: 33.6 %). Any alcohol intake before the first pregnancy was associated with an increased risk of breast cancer (HR 1.35, 95 % CI 1.10-1.66 for drinking compared with abstention), whereas any intake after the first pregnancy was not (HR 0.89, 95 % CI 0.72-1.09).
  
  
  
  Limiting alcohol intake before the first pregnancy might reduce women's risk of breast cancer.
authors.affiliation: Cancer Epidemiology Centre, Cancer Council Victoria, 615 St Kilda Road, Melbourne, VIC, 3004, Australia. harindra.jayasekara@cancervic.org.au.|Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, 207 Bouverie Street, Melbourne, VIC, 3010, Australia. harindra.jayasekara@cancervic.org.au.
authors.forename: Harindra
authors.initials: H
authors.lastname: Jayasekara
authors.affiliation: Cancer Epidemiology Centre, Cancer Council Victoria, 615 St Kilda Road, Melbourne, VIC, 3004, Australia.|Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, 207 Bouverie Street, Melbourne, VIC, 3010, Australia.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: MacInnis
authors.affiliation: Cancer Epidemiology Centre, Cancer Council Victoria, 615 St Kilda Road, Melbourne, VIC, 3004, Australia.
authors.forename: Allison M
authors.initials: AM
authors.lastname: Hodge
authors.affiliation: Centre for Alcohol Policy Research, La Trobe University, 215 Franklin Street, Melbourne, VIC, 3000, Australia.|Centre for Health Equity, Melbourne School of Population and Global Health, The University of Melbourne, 207 Bouverie Street, Carlton, VIC, 3010, Australia.|Centre for Social Research on Alcohol and Drugs, Stockholm University, 106 91, Stockholm, Sweden.
authors.forename: Robin
authors.initials: R
authors.lastname: Room
authors.affiliation: Cancer Epidemiology Centre, Cancer Council Victoria, 615 St Kilda Road, Melbourne, VIC, 3004, Australia.|Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, 207 Bouverie Street, Melbourne, VIC, 3010, Australia.
authors.forename: Roger L
authors.initials: RL
authors.lastname: Milne
authors.affiliation: Cancer Epidemiology Centre, Cancer Council Victoria, 615 St Kilda Road, Melbourne, VIC, 3004, Australia.|Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, 207 Bouverie Street, Melbourne, VIC, 3010, Australia.
authors.forename: John L
authors.initials: JL
authors.lastname: Hopper
authors.affiliation: Cancer Epidemiology Centre, Cancer Council Victoria, 615 St Kilda Road, Melbourne, VIC, 3004, Australia.|Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, 207 Bouverie Street, Melbourne, VIC, 3010, Australia.
authors.forename: Graham G
authors.initials: GG
authors.lastname: Giles
authors.affiliation: Cancer Epidemiology Centre, Cancer Council Victoria, 615 St Kilda Road, Melbourne, VIC, 3004, Australia.|Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, 207 Bouverie Street, Melbourne, VIC, 3010, Australia.
authors.forename: Dallas R
authors.initials: DR
authors.lastname: English
mesh_terms: D000230:Adenocarcinoma / Q000453:epidemiology / Q000209:etiology*; D000293:Adolescent; D000328:Adult; D000368:Aged; D000428:Alcohol Drinking / Q000009:adverse effects*; D001943:Breast Neoplasms / Q000453:epidemiology / Q000209:etiology*; D005260:Female; D006801:Humans; D015994:Incidence; D008572:Menarche; D008875:Middle Aged; D011247:Pregnancy; D011446:Prospective Studies; D012307:Risk Factors; D055815:Young Adult
keywords: Alcohol consumption; Breast cancer; First full-term pregnancy; Prospective study