title: Dietary fat and fiber in relation to risk of breast cancer. An 8-year follow-up.
abstract: OBJECTIVE
  To address the hypotheses that dietary fat increases and fiber decreases the risk of breast cancer.
  
  
  METHODS
  Prospective cohort study with dietary assessment at baseline, using a validated, self-administered food frequency questionnaire.
  
  
  METHODS
  89,494 women in the Nurses' Health Study who were 34 through 59 years of age in 1980 and who were followed up for 8 years (> 95% complete).
  
  
  RESULTS
  1439 incident cases of breast cancer were diagnosed, including 774 among postmenopausal women. After adjustment for age, established risk factors, and total energy intake, we observed no evidence of any positive association between total fat intake and breast cancer incidence (relative risks [RRs] for increasing quintiles of fat intake were 1.0, 0.85, 0.96, 0.91, and 0.90; 95% confidence interval for highest vs lowest quintile, 0.77 to 1.07). Among postmenopausal women alone, corresponding RRs were 1.0, 0.89, 1.00, 0.95, and 0.91. Comparing extreme deciles of total fat intake (> or = 49% vs < 29% of total energy intake), the RR was 0.86 (95% confidence interval, 0.67 to 1.08). A similar absence of any positive association was observed without adjustment for energy intake; for tumors less than 2 cm as well as 2 cm or greater in diameter; for saturated, monounsaturated, and polyunsaturated fat; and after excluding the first 4 years of follow-up. Also, we found no suggestion of any positive association when using a more detailed and precise dietary questionnaire completed in 1984 (666 subsequent cases), even when women consuming less than 25% of energy from fat were used as the comparison group. No suggestion of a protective effect of dietary fiber was observed (RRs for increasing quintiles were 1.0, 0.95, 0.93, 1.02, and 1.02).
  
  
  CONCLUSIONS
  These data provide evidence against both an adverse influence of fat intake and a protective effect of fiber consumption by middle-aged women on breast cancer incidence over 8 years. Nevertheless, the positive association between intake of animal fat and risk of colon cancer observed in many studies provides ample reason to limit this source of energy.
authors.affiliation: Channing Laboratory, Department of Medicine, Brigham and Women's Hospital, Boston, MA 02215.
authors.forename: W C
authors.initials: WC
authors.lastname: Willett
authors.forename: D J
authors.initials: DJ
authors.lastname: Hunter
authors.forename: M J
authors.initials: MJ
authors.lastname: Stampfer
authors.forename: G
authors.initials: G
authors.lastname: Colditz
authors.forename: J E
authors.initials: JE
authors.lastname: Manson
authors.forename: D
authors.initials: D
authors.lastname: Spiegelman
authors.forename: B
authors.initials: B
authors.lastname: Rosner
authors.forename: C H
authors.initials: CH
authors.lastname: Hennekens
authors.forename: F E
authors.initials: FE
authors.lastname: Speizer
mesh_terms: D000328:Adult; D015982:Bias; D001943:Breast Neoplasms / Q000453:epidemiology / Q000209:etiology*; D015331:Cohort Studies; D004041:Dietary Fats / Q000008:administration & dosage / Q000009:adverse effects*; D004043:Dietary Fiber / Q000008:administration & dosage*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008875:Middle Aged; D011446:Prospective Studies; D012307:Risk Factors; D014481:United States / Q000453:epidemiology
chemical_list: D004041:Dietary Fats; D004043:Dietary Fiber