National study shows five fruits and vegetables a day are as good as it gets to prevent breast cancer recurrence

[Source: Donna Breckenridge, Arizona Cancer Center] - Over a period of approximately seven years, 479 Arizona breast cancer survivors participated in the largest national randomized clinical trial to assess the influence of diet on the recurrence of breast cancer. The Arizona Cancer Center is one of six institutions to enroll women in the multi-center Women’s Healthy Eating and Living (WHEL) study. The findings, reported in the July 18 issue of the Journal of the American Medical Association, suggest that a diet very high in vegetables, fruit, and fiber, and low in fat does not reduce breast cancer recurrence or death in early stage breast cancer survivors when compared to guidelines promoted by the U.S. Department of Agriculture (USDA).

The WHEL study included 3,088 breast cancer survivors between 18 – 70 years of age. Participants were randomly assigned to one of two diet groups. One group followed the 5-a-Day guidelines promoted by the USDA, while the other group was asked to follow a dietary pattern that included 5 vegetable servings, 16 ounces of vegetable juice, 3 fruit servings, 30 grams of fiber, and 15 – 20 percent of total daily energy intake from fat. Participants were followed for 6–11 years, with a median participation of 7 years Results indicate that for women diagnosed with early stage breast cancer there was no additional benefit in consuming more than the USDA-recommended amount of fruits and vegetables. The groups were nearly equal in disease-free survival curves.

The Arizona Cancer Center also conducted the study’s dietary assessments, and study authors include Cancer Center members Cynthia Thomson, PhD, assistant professor of nutritional sciences, and Cheryl Ritenbaugh, PhD, MPH, professor of family and community medicine. “The benefit of a healthy diet is the same as increasing to 13 or 14 servings of fruits and vegetables daily,” says Dr. Thomson. “A diet including 5 to 7 servings of fruits and vegetables daily, along with keeping fat intake below 30 percent, is adequate to help prevent breast cancer recurrence.” Study officials are quick to point out that results speak only to breast cancer survivors. They did not address whether the high-vegetable/fruit/fiber and low-fat diet would alter the risk of primary breast cancer.

The WHEL study also did not focus on weight control, which may be an important factor in breast cancer recurrence and survival. A study published in the June 10, 2007 issue of the Journal of Clinical Oncology by WHEL study researchers, including Dr. Thomson, demonstrated that eating 5 to 7 fruits and vegetables a day and being moderately active improved survival, even in overweight women. “It is critically important that we continue to study the changes in Western lifestyle associated with progression-free survival in patients with common cancers such as breast, colon and prostate cancers,” says Arizona Cancer Center David S. Alberts, MD. “The WHEL trial was beautifully designed to evaluate the impact of a low-fat, high fruit and vegetables diet on early stage breast cancer recurrence. Although this dietary intervention did not seem to work, the WHEL study analysis suggests that the addition of regular physical activity (e.g., 30-60 minutes of walking daily) to a low fat/high vegetable diet will have a pronounced impact on progression-free survival in these women.”

The study, based at UC San Diego Rebecca and John Moores Cancer Center, also involved University of California, Davis, Stanford University, Kaiser Permanente in Oakland and Portland, and the University of Texas M.D. Anderson Cancer Center in Houston.

Full text of the article is available at http://jama.ama-assn.org/cgi/content/full/298/3/289. A broadcast quality video news report is also available through www.thejamareport.org .