title: Alcohol and postmenopausal breast cancer risk defined by estrogen and progesterone receptor status: a prospective cohort study.
abstract: BACKGROUND
  Alcohol intake has been reported to be positively associated with an increased risk of postmenopausal breast cancer; however, the association with the estrogen receptor (ER) and progesterone receptor (PR) status of the breast tumors remains unclear.
  
  
  METHODS
  Self-reported data on alcohol consumption were collected in 1987 and 1997 from 51,847 postmenopausal women in the population-based Swedish Mammography Cohort. Through June 30, 2004, 1188 invasive breast cancer case patients with known ER and PR status were identified during an average 8.3-year follow-up. We used Cox proportional hazards models to estimate multivariable relative risks (RRs) of breast cancer, adjusting for age; family history of breast cancer; body mass index; height; parity; age at menarche, first birth, and menopause; education level; use of postmenopausal hormones; and diet. Heterogeneity among groups was evaluated using the Wald test. All statistical tests were two-sided.
  
  
  RESULTS
  Alcohol consumption was associated with an increased risk for the development of ER-positive (+) tumors, irrespective of PR status (highest intake [> or = 10 g of alcohol per day] versus nondrinkers, multivariable RR = 1.35, 95% confidence interval [CI] = 1.02 to 1.80; Ptrend < .049 for ER+PR+ tumors; and RR = 2.36, 95% CI = 1.56 to 3.56; Ptrend < .001 for ER+PR-tumors). The absolute rate of ER+ breast cancer (standardized to the age distribution of person-years experienced by all study participants using 5-year age categories) was 232 per 100,000 person-years among women in the highest category of alcohol intake, and 158 per 100,000 person-years among nondrinkers. No association was observed between alcohol intake and the risk of developing ER-tumors. Furthermore, we observed a statistically significant interaction between alcohol intake and the use of postmenopausal hormones on the risk for ER+PR+ tumors (Pinteraction = .039).
  
  
  CONCLUSIONS
  The observed association between risk of developing postmenopausal ER+ breast cancer and alcohol drinking, especially among those women who use postmenopausal hormones, may be important, because the majority of breast tumors among postmenopausal women overexpress ER.
authors.affiliation: The National Institute of Environmental Medicine, Division of Nutritional Epidemiology, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Reiko
authors.initials: R
authors.lastname: Suzuki
authors.forename: Weimin
authors.initials: W
authors.lastname: Ye
authors.forename: Tove
authors.initials: T
authors.lastname: Rylander-Rudqvist
authors.forename: Shigehira
authors.initials: S
authors.lastname: Saji
authors.forename: Graham A
authors.initials: GA
authors.lastname: Colditz
authors.forename: Alicja
authors.initials: A
authors.lastname: Wolk
mesh_terms: D000368:Aged; D000428:Alcohol Drinking / Q000009:adverse effects* / Q000453:epidemiology*; D001943:Breast Neoplasms / Q000737:chemistry / Q000000981:diagnostic imaging / Q000453:epidemiology* / Q000209:etiology*; D016022:Case-Control Studies; D015331:Cohort Studies; D015986:Confounding Factors, Epidemiologic; D005260:Female; D006801:Humans; D008327:Mammography; D008875:Middle Aged; D015999:Multivariate Analysis; D017698:Postmenopause; D016016:Proportional Hazards Models; D011446:Prospective Studies; D011960:Receptors, Estrogen / Q000032:analysis*; D011980:Receptors, Progesterone / Q000032:analysis*; D012107:Research Design; D018570:Risk Assessment; D012307:Risk Factors; D013548:Sweden / Q000453:epidemiology
chemical_list: D011960:Receptors, Estrogen; D011980:Receptors, Progesterone