Healthy Diet Fails to Reduce Breast Cancer Recurrences


A low-fat diet very high in vegetables, fruit, and fiber failed to decrease recurrences in women who had survived early-stage breast cancer, reported Dr. John P. Pierce and his associates in the Women's Healthy Eating and Living study.

Even though the women substantially increased their intake of vegetables, fruit, and fiber and cut down on fat consumption, their rates of breast cancer recurrence, new primary cancers, metastases, and mortality were no different from those of control subjects after a mean of 7 years of follow-up, the researchers said.

The WHEL study was a randomized trial “based on the recommendations of a national committee of experts called to respond to a 1993 challenge grant from a private philanthropist who believed that the role of diet in preventing cancer progression deserved scientific study,” said Dr. Pierce of the University of California, San Diego, and his associates.

Subjects were 3,088 women aged 18-70 years who had been treated with axillary dissection and total mastectomy or lumpectomy followed by radiation at seven medical centers between 1995 and 2000. A total of 1,537 women were randomly assigned to a dietary intervention involving frequent telephone consultation, cooking classes, and monthly newsletters.

The daily dietary target was intake of five vegetable servings plus 16 ounces of vegetable juice, three fruit servings, 30 g fiber, and 15%-20% of total energy intake from fat.

The remaining subjects, who constituted the control group, were given print materials encouraging them to follow the government's recommended daily intake of five servings of vegetables and fruit, 20 g or more of fiber, and less than 30% total energy intake from fat. They also were offered cooking classes and newsletters, but most did not participate.

The dietary patterns of the intervention group changed dramatically with the introduction of the diet, and most of the women maintained their healthy eating patterns throughout follow-up. For example, at 1-year follow-up the intervention group averaged approximately eight servings of vegetables each day. Total plasma carotenoid level, a biomarker of vegetable and fruit intake, was 73% higher in the intervention group than in the control group.

However, the same proportion of subjects in both groups–16%–developed a breast cancer recurrence, metastasis, or a new primary cancer, and “the disease-free survival curves were virtually identical across groups,” the investigators said (JAMA 2007;298:289-98).

All-cause mortality was 10% in both groups. More than 80% of the deaths in both groups were caused by breast cancer.

There were no differences between the intervention and control groups in depression, social support, or quality of life during the first year of treatment, when the intervention was most intense. “Therefore, we believe that our investigation provides an adequate test of whether the study dietary pattern provided an added benefit over the dietary pattern of the comparison group of women,” Dr. Pierce and his associates said.

The study diet included five vegetable servings, 16 oz vegetable juice, and three fruit servings. Lynda Banzi/Elsevier Global Medical News

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