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Influence of a Diet Very High in Vegetables, Fruit, and Fiber and
Low in Fat on Prognosis Following Treatment for Breast Cancer: The
Women's Healthy Eating and Living (WHEL) Randomized Trial |
| Considerable evidence from
preclinical studies indicates that plant-derived foods
contain anticarcinogens. A comprehensive review of the
literature found that a diet
high in vegetables and fruit probably decreases breast
cancer risk and that a diet high in total fat possibly
increases risk. However, evidence of an
association between a diet high in vegetables and fruit
and low in total fat and prevention of cancer progression has
been mixed in epidemiological studies.An interim analysis
of data from the Women's Intervention Nutrition Study (WINS),
which assessed the effect of a dietary intervention designed
to reduce fat intake on relapse-free survival in breast cancer
patients, found that the intervention was associated with
a marginally statistically significant improvement in
relapse-free survival. To our knowledge, no other
clinical trials investigating dietary change and breast
cancer survival have been reported.
The Women's Healthy Eating and Living (WHEL) Study was a randomized trial assessing whether a dietary pattern very high in vegetables, fruit, and fiber and low in fat reduces the risks of recurrent and new primary breast cancer and all-cause mortality among women with previously treated early stage breast cancer. The study was 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 to enable cancer survivors to make decisions without having "to rely on folklore, rumor and hearsay." Evidence is lacking that a dietary pattern high in vegetables, fruit, and fiber and low in total fat can influence breast cancer recurrence or survival. to assess whether a major increase in vegetable, fruit, and fiber intake and a decrease in dietary fat intake reduces the risk of recurrent and new primary breast cancer and all-cause mortality among women with previously treated early stage breast cancer. Multi-institutional randomized controlled trial of dietary change in 3088 women previously treated for early stage breast cancer who were 18 to 70 years old at diagnosis. Women were enrolled between 1995 and 2000 and followed up through June 1, 2006. The intervention group (n = 1537) was randomly assigned to receive a telephone counseling program supplemented with cooking classes and newsletters that promoted daily targets of 5 vegetable servings plus 16 oz of vegetable juice; 3 fruit servings; 30 g of fiber; and 15% to 20% of energy intake from fat. The comparison group (n = 1551) was provided with print materials describing the "5-A-Day" dietary guidelines. From comparable dietary patterns at baseline, a conservative imputation analysis showed that the intervention group achieved and maintained the following statistically significant differences vs the comparison group through 4 years: servings of vegetables, +65%; fruit, +25%; fiber, +30%, and energy intake from fat, –13%. Plasma carotenoid concentrations validated changes in fruit and vegetable intake. Throughout the study, women in both groups received similar clinical care. Over the mean 7.3-year follow-up, 256 women in the intervention group (16.7%) vs 262 in the comparison group (16.9%) experienced an invasive breast cancer event (adjusted hazard ratio, 0.96; 95% confidence interval, 0.80-1.14; P = .63), and 155 intervention group women (10.1%) vs 160 comparison group women (10.3%) died (adjusted hazard ratio, 0.91; 95% confidence interval, 0.72-1.15; P = .43). No significant interactions were observed between diet group and baseline demographics, characteristics of the original tumor, baseline dietary pattern, or breast cancer treatment. Conclusion Among survivors of early stage breast cancer, adoption of a diet that was very high in vegetables, fruit, and fiber and low in fat did not reduce additional breast cancer events or mortality during a 7.3-year follow-up period.
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