Low-Fat Dietary Intervention and Overall Survival After Breast Cancer Diagnosis

Key Points

  • Overall postdiagnosis survival was significantly better in the reduced-fat intervention group.
  • The reduced-fat intervention group had fewer deaths due to breast cancer, other cancers, and cardiovascular disease. 

In an analysis from the Women’s Health Initiative (WHI) trial reported in JAMA Oncology, Chlebowski et al found that overall survival after the diagnosis of incident breast cancer was improved in women in the reduced-fat dietary intervention group vs control group, reflecting reduced mortality from a number of  different causes. In the trial, a low-fat eating pattern was associated with the reduced risk of death after breast cancer measured from randomization.  

Study Details

In the WHI trial, 48,835 postmenopausal women with no previous breast cancer diagnosis and dietary fat intake of > 32% were enrolled at 40 U.S. sites between 1993 and 1998 and randomly assigned to dietary intervention with a target of reducing fat intake to 20% of energy and increasing fruit, vegetable, and grain intake (n = 19,541) or a usual-diet control group (n = 29,294). Participants who were diagnosed with incident breast cancer continued to participate in the study. The current secondary analysis assessed overall survival among women diagnosed with breast cancer during the dietary intervention period (median = 8.5 years) as measured from the time of cancer diagnosis through a median 11.5-year postdiagnosis follow-up.

Overall Survival After Diagnosis

Among 1,764 women diagnosed with breast cancer during the dietary intervention period, mean ages were 62.7 years at screening and 67.6 years at diagnosis. A total of 516 deaths occurred, with 10-year overall survival being 82% in the reduced-fat dietary intervention participants vs 78% in the usual-diet participants (hazard ratio [HR] = 0.78, P = .01). The dietary intervention group had fewer deaths from breast cancer (68 vs 120, HR = 0.86, 95% confidence interval [CI] = 0.64–1.17), other cancers (36 vs 65, HR = 0.76, 95% CI = 0.50–1.17), and cardiovascular disease (27 vs 64, HR = 0.62, 95% CI = 0.39–0.99).

The investigators concluded, “In women who received a diagnosis of breast cancer during the dietary intervention period, those in the dietary group had increased overall survival. The increase is due, in part, to better survival from several causes of death.”

The WHI program is supported by the National Heart, Lung, and Blood Institute and National Institutes of Health, and the current study was additionally supported by a grant from the American Institute for Cancer Research.

Rowan T. Chlebowski, MD, PhD, of the City of Hope National Medical Center, is the corresponding author for the JAMA Oncology article.

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.


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