title: Low-fat dietary pattern and cancer incidence in the Women's Health Initiative Dietary Modification Randomized Controlled Trial.
abstract: BACKGROUND
  The Women's Health Initiative Dietary Modification (DM) Randomized Controlled Trial evaluated the effects of a low-fat dietary pattern on chronic disease incidence, with breast cancer and colorectal cancer as primary outcomes. The trial protocol also listed ovarian cancer and endometrial cancer as outcomes that may be favorably affected by the intervention.
  
  
  METHODS
  A total of 48,835 postmenopausal women were randomly assigned during 1993-1998 to a DM intervention (n = 19,541) or comparison (usual diet; n = 29,294) group and followed up for an average of 8.1 years. The intervention goal was to reduce total fat intake to 20% of energy and to increase consumption of vegetables, fruits, and grains. Cancer outcomes were verified by pathology report review. We used weighted log-rank tests to compare incidence of invasive cancers of the ovary and endometrium, total invasive cancer, and invasive cancers at other sites between the groups. All statistical tests were two-sided.
  
  
  RESULTS
  Ovarian cancer risk was lower in the intervention than in the comparison group (P = .03). Although the overall ovarian cancer hazard ratio (HR) was not statistically significantly less than 1.0, the hazard ratio decreased with increasing intervention duration (P(trend) = .01). For the first 4 years, the risk for ovarian cancer was similar in the intervention and control groups (0.52 cases per 1000 person-years in the intervention group versus 0.45 per 1000 person-years in the comparison group; HR = 1.16, 95% confidence interval [CI] = 0.73 to 1.84); over the next 4.1 years, the risk was lower in the intervention group (0.38 cases per 1000 person-years in the intervention group versus 0.64 per 1000 person-years in the comparison group; HR = 0.60, 95% CI = 0.38 to 0.96). Risk of cancer of the endometrium did not differ between the groups (P = .18). The estimated risk of total invasive cancer was slightly lower in the intervention group than in the control group (HR = 0.95, 95% CI = 0.89 to 1.01; P = .10).
  
  
  CONCLUSIONS
  A low-fat dietary pattern may reduce the incidence of ovarian cancer among postmenopausal women.
authors.affiliation: Division of Public Health Sciences, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue North, PO Box 19024, Seattle, WA 98109-1024, USA. rprentic@fhcrc.org
authors.forename: Ross L
authors.initials: RL
authors.lastname: Prentice
authors.forename: Cynthia A
authors.initials: CA
authors.lastname: Thomson
authors.forename: Bette
authors.initials: B
authors.lastname: Caan
authors.forename: F Allan
authors.initials: FA
authors.lastname: Hubbell
authors.forename: Garnet L
authors.initials: GL
authors.lastname: Anderson
authors.forename: Shirley A A
authors.initials: SA
authors.lastname: Beresford
authors.forename: Mary
authors.initials: M
authors.lastname: Pettinger
authors.forename: Dorothy S
authors.initials: DS
authors.lastname: Lane
authors.forename: Lawrence
authors.initials: L
authors.lastname: Lessin
authors.forename: Shagufta
authors.initials: S
authors.lastname: Yasmeen
authors.forename: Baljinder
authors.initials: B
authors.lastname: Singh
authors.forename: Janardan
authors.initials: J
authors.lastname: Khandekar
authors.forename: James M
authors.initials: JM
authors.lastname: Shikany
authors.forename: Suzanne
authors.initials: S
authors.lastname: Satterfield
authors.forename: Rowan T
authors.initials: RT
authors.lastname: Chlebowski
mesh_terms: D000368:Aged; D018269:Carcinoma, Endometrioid / Q000453:epidemiology / Q000517:prevention & control; D018284:Cystadenocarcinoma, Serous / Q000453:epidemiology / Q000517:prevention & control; D004041:Dietary Fats / Q000008:administration & dosage*; D002523:Edible Grain; D016889:Endometrial Neoplasms / Q000453:epidemiology* / Q000208:ethnology / Q000473:pathology / Q000517:prevention & control*; D005247:Feeding Behavior; D005260:Female; D005500:Follow-Up Studies; D005638:Fruit; D006801:Humans; D015994:Incidence; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D009367:Neoplasm Staging; D009369:Neoplasms / Q000453:epidemiology / Q000517:prevention & control; D016017:Odds Ratio; D010051:Ovarian Neoplasms / Q000453:epidemiology* / Q000208:ethnology / Q000473:pathology / Q000517:prevention & control*; D017698:Postmenopause; D016016:Proportional Hazards Models; D018570:Risk Assessment; D012307:Risk Factors; D014481:United States / Q000453:epidemiology; D014675:Vegetables; D015431:Weight Loss; D016387:Women's Health
chemical_list: D004041:Dietary Fats