Bottom Line: Women diagnosed with breast cancer during the Women's Health Initiative Dietary Modification trial who were following a lower-fat diet had increased breast cancer overall survival, although the increase was likely partly due to better survival from several causes of death.
Why The Research Is Interesting: This study helps address the issue of postdiagnosis dietary intervention influences by providing findings for breast cancer overall survival measured from breast cancer diagnosis because study participants with breast cancer continued to participate in dietary modification activities.
Who and When: 48,835 postmenopausal women with no previous breast cancer and dietary fat intake of more than 32 percent based on a food questionnaire
What (Study Interventions and Oucomes): 19,541 participants took part in a dietary intervention to reduce their fat intake to 20 percent of calories and increase the amount of fruits, vegetables and grains they were eating, while 29,294 participants served as a usual-diet comparison group (interventions); breast cancer overall survival for new breast cancers diagnosed during the 8.5 years of the dietary intervention and examined later after 11.5 years of postdiagnosis follow-up.
Study Design: This was a secondary analysis of the Women's Health Initiative randomized clinical trial
Authors: Rowan T. Chlebowski, M.D., Ph.D., of City of Hope National Medical Center, Duarte, California, and coauthors
Results: 1,764 women diagnosed with breast cancer during the dietary intervention; breast cancer overall survival was higher for women in the lower-fat group than in the usual-diet group; and in the group where women ate less fat, there were fewer deaths from breast cancer, other cancers and cardiovascular disease
Limitations: Modest increases in vegetable, fruit and grain intake, the need for confirmatory trials and incomplete breast cancer therapy information.