FROM THE JOURNAL OF CLINICAL ONCOLOGY

Women can reduce their risk of dying should they receive a breast cancer diagnosis by following a low-fat diet, suggests an analysis from the phase III multicenter randomized Women’s Health Initiative Dietary Modification trial.

Investigators led by Rowan T. Chlebowski, MD, PhD , formerly of the Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, California, and now at City of Hope National Medical Center, Duarte, California, analyzed data from 48,835 postmenopausal women who had never had breast cancer and had normal mammograms. The women were randomly assigned 2:3 to a diet aimed at reducing fat intake to 20% of energy and increasing intake of fruits, vegetables, and grains or to a usual diet.

During the median 8.5-year dietary intervention, the rate of deaths attributed to breast cancer was 0.016% per year in the low-fat diet group and 0.024% per year in the usual diet group, a difference that was not significant (P = .08), Dr. Chlebowski and associates reported (J Clin Oncol. 2017 June 27. doi: 10.1200/JCO.2016.72.0326 ).

However, the rate of deaths after breast cancer from any cause was 0.025% per year in the former group and 0.038% per year in the latter group, a difference that translated to a more than one-third reduction in risk (hazard ratio, 0.65; P = .02).

Similarly, during the median 16.1-year total follow-up, the rate of deaths attributed to breast cancer was 0.035% per year in the low-fat diet group and 0.039% per year in the usual diet group, a difference that was not significant (P =. 41). However, the rate of deaths after breast cancer from any cause was 0.085% per year in the former group and 0.11% per year in the latter group, a difference that translated to a nearly one-fifth reduction in the risk of death (HR, 0.82; P = .01).

In subgroup analyses, there were significant interactions whereby benefit was greater for women who had a baseline waist circumference of at least 88 cm and increased with the baseline percentage of total energy from fat.

“The lower risk of poor prognosis, ER+, PR– breast cancers … in the dietary group contributed to the favorable dietary effect on death after breast cancer,” the investigators noted. “An additional factor that potentially influenced deaths after breast cancer could be a favorable dietary influence on mortality as a result of other causes, including cardiovascular disease.”

“Future studies of other lifestyle interventions on breast cancer incidence and outcome could incorporate some form of a low-fat dietary pattern as a base,” they concluded.

op@frontlinemedcom.com

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