title: Dietary fat reduction and breast cancer outcome: interim efficacy results from the Women's Intervention Nutrition Study.
abstract: BACKGROUND
  Preclinical and observational studies suggest a relationship between dietary fat intake and breast cancer, but the association remains controversial. We carried out a randomized, prospective, multicenter clinical trial to test the effect of a dietary intervention designed to reduce fat intake in women with resected, early-stage breast cancer receiving conventional cancer management.
  
  
  METHODS
  A total of 2437 women were randomly assigned between February 1994 and January 2001 in a ratio of 40:60 to dietary intervention (n = 975) or control (n = 1462) groups. An interim analysis was performed after a median follow-up of 60 months when funding for the intervention ceased. Mean differences between dietary intervention and control groups in nutrient intakes and anthropometric variables were compared with t tests. Relapse-free survival was examined using Kaplan-Meier analysis, stratified log-rank tests, and Cox proportional hazards models. Statistical tests were two-sided.
  
  
  RESULTS
  Dietary fat intake was lower in the intervention than in the control group (fat grams/day at 12 months, 33.3 [95% confidence interval {CI} = 32.2 to 34.5] versus 51.3 [95% CI = 50.0 to 52.7], respectively; P<.001), corresponding to a statistically significant (P = .005), 6-pound lower mean body weight in the intervention group. A total of 277 relapse events (local, regional, distant, or ipsilateral breast cancer recurrence or new contralateral breast cancer) have been reported in 96 of 975 (9.8%) women in the dietary group and 181 of 1462 (12.4%) women in the control group. The hazard ratio of relapse events in the intervention group compared with the control group was 0.76 (95% CI = 0.60 to 0.98, P = .077 for stratified log rank and P = .034 for adjusted Cox model analysis). Exploratory analyses suggested a differential effect of the dietary intervention based on hormonal receptor status.
  
  
  CONCLUSIONS
  A lifestyle intervention reducing dietary fat intake, with modest influence on body weight, may improve relapse-free survival of breast cancer patients receiving conventional cancer management. Longer, ongoing nonintervention follow-up will address original protocol design plans, which called for 3 years of follow-up after completion of recruitment.
authors.affiliation: Department of Medicine, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, 1124 West Carson St., Building J-3, Torrance, CA 90502-2064, USA. rchlebow@whi.org
authors.forename: Rowan T
authors.initials: RT
authors.lastname: Chlebowski
authors.forename: George L
authors.initials: GL
authors.lastname: Blackburn
authors.forename: Cynthia A
authors.initials: CA
authors.lastname: Thomson
authors.forename: Daniel W
authors.initials: DW
authors.lastname: Nixon
authors.forename: Alice
authors.initials: A
authors.lastname: Shapiro
authors.forename: M Katherine
authors.initials: MK
authors.lastname: Hoy
authors.forename: Marc T
authors.initials: MT
authors.lastname: Goodman
authors.forename: Armando E
authors.initials: AE
authors.lastname: Giuliano
authors.forename: Njeri
authors.initials: N
authors.lastname: Karanja
authors.forename: Philomena
authors.initials: P
authors.lastname: McAndrew
authors.forename: Clifford
authors.initials: C
authors.lastname: Hudis
authors.forename: John
authors.initials: J
authors.lastname: Butler
authors.forename: Douglas
authors.initials: D
authors.lastname: Merkel
authors.forename: Alan
authors.initials: A
authors.lastname: Kristal
authors.forename: Bette
authors.initials: B
authors.lastname: Caan
authors.forename: Richard
authors.initials: R
authors.lastname: Michaelson
authors.forename: Vincent
authors.initials: V
authors.lastname: Vinciguerra
authors.forename: Salvatore
authors.initials: S
authors.lastname: Del Prete
authors.forename: Marion
authors.initials: M
authors.lastname: Winkler
authors.forename: Rayna
authors.initials: R
authors.lastname: Hall
authors.forename: Michael
authors.initials: M
authors.lastname: Simon
authors.forename: Barbara L
authors.initials: BL
authors.lastname: Winters
authors.forename: Robert M
authors.initials: RM
authors.lastname: Elashoff
mesh_terms: D000328:Adult; D000368:Aged; D001835:Body Weight; D001943:Breast Neoplasms / Q000178:diet therapy* / Q000473:pathology / Q000628:therapy; D018270:Carcinoma, Ductal, Breast / Q000178:diet therapy; D018275:Carcinoma, Lobular / Q000178:diet therapy; D004041:Dietary Fats / Q000008:administration & dosage*; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008207:Lymphatic Metastasis; D008875:Middle Aged; D009367:Neoplasm Staging; D016016:Proportional Hazards Models; D016896:Treatment Outcome
chemical_list: D004041:Dietary Fats