Women who adopted a low-fat diet that was very rich in vegetables, fruit, and fiber after treatment for breast cancer did not reduce their risk of recurrence compared with similar women who consumed 5 or more servings of fruits and vegetables a day. After 7 years, both groups of women had essentially the same risk of recurrence, incidence of new primary breast cancers, and risk of overall mortality.

Even women whose diets at baseline were low in fruits, vegetables, or fiber or high in fat did not appear to benefit from the intervention, according to findings in the July 18 Journal of the American Medical Association (JAMA). The results are from the Women's Healthy Eating and Living (WHEL) study, a randomized controlled trial that included 3,088 women who were treated for early-stage breast cancer.

The researchers caution against applying their findings to populations beyond those in the study, which included women who had completed their initial therapy and excluded women diagnosed after age 70. The findings appear to be at odds with interim results from the Women's Intervention Nutrition Study (WINS), which suggest that a low-fat diet may help prevent breast cancer recurrence in some women.

Different patterns of weight gain and loss between the trials may account for some of the varying results, according to an editorial in JAMA. Women in both arms of the WHEL trial on average gained weight, whereas women in the intervention arm of WINS lost weight. New studies that assess interventions based on physical activity and energy intake for breast cancer survivors are warranted, the editorial concludes.