Dietary Fat Reduction and Breast Cancer Outcome: Interim Efficacy Results From the Women's Intervention Nutrition Study

Rowan T. Chlebowski, George L. Blackburn, Cynthia A. Thomson, Daniel W. Nixon, Alice Shapiro, M. Katherine Hoy, Marc T. Goodman, Armando E. Giuliano, Njeri Karanja, Philomena McAndrew, Clifford Hudis, John Butler (+11 others)
2006 Journal of the National Cancer Institute  
ARTICLES 1767 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
more » ... 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 followup 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, stratifi ed 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% confi dence interval {CI} = 32.2 to 34.5] versus 51.3 [95% CI = 50.0 to 52.7], respectively; P <.001), corresponding to a statistically signifi cant ( 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 stratifi ed 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 infl uence on body weight, may improve relapse-free survival of breast cancer patients re ceiving 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. [J Natl Cancer Inst 2006;98: 1767 -76 ] The question of the infl uence of dietary fat on breast cancer has been controversial. Whereas preclinical and human
doi:10.1093/jnci/djj494 pmid:17179478 fatcat:hj3zivpz7va3lj64nvzjcn55xa