Early findings from the Women's Health Initiative Dietary Modification (WHI DM) trial indicated a reduction in breast cancer mortality in women who followed a low-fat diet. Now, long-term follow-up data from this prevention trial, spanning >16 years, have been reported. As lead author, Rowan Chlebowski, explains: “observational studies examining the potential association of a low-fat dietary pattern with breast cancer incidence and outcome have provided mixed results. The current WHI DM study was designed to resolve this issue.”

In total, 48,835 postmenopausal women with normal mammograms and without a prior history of breast cancer were randomly assigned to a low-fat diet (20% reduction in fat intake, and increased intake of vegetables, grains and fruits) or to their usual diet. The long-term results of the study are striking. Postmenopausal women with breast cancer who followed a low-fat dietary pattern had a significantly lower incidence of death. During the 8.5-year intervention period of the trial, fewer deaths due to breast cancer occurred in the low-fat dietary group, although this outcome was not statistically significant.

...only a modest reduction in fat intake...could achieve positive results

In the follow-up period, however, the number of deaths among women who received a breast cancer diagnosis were significantly reduced as a result of dietary intervention: 40 deaths versus 94 deaths. “These results suggest that only a modest reduction in fat intake with minimal weight loss could achieve positive results,” Chlebowski opines. Encouragingly, this study shows how patients can proactively improve their outcomes, as a modest reduction in fat intake with minimal weight loss is an achievable lifestyle goal for many, and can provide impressive results.