Low-fat diet possibly linked to lower risk of ovarian cancer

[Source: Donna Breckenridge, Arizona Cancer Center] -- A low-fat diet may decrease the risk of ovarian cancer in postmenopausal women, according to a study published online October 9 in the Journal of the National Cancer Institute. “Until now, the relationship between diet and ovarian cancer risk has received little attention, and it is important to know that the risk of this cancer also can be reduced by maintaining a healthy diet,” says Cynthia A. Thomson, PhD, RD, assistant professor of nutritional sciences and public health at the Arizona Cancer Center. Dr. Thomson is the second author on the study. Previous reports from the Women’s Health Initiative Dietary Modification Randomized Controlled Trial examined the effect of a low-fat diet on the risk of breast and colorectal cancer in postmenopausal women, but it was not yet known whether the same diet would alter ovarian cancer risk. “The results of this study are extremely important, in that they provide an opportunity for post-menopausal women to lower their risk of developing ovarian cancer by following a healthy diet, low in fat,” says Arizona Cancer Center Director David S. Alberts, MD, who specializes in the treatment of ovarian cancer.

Lead author Ross Prentice, Ph.D., of Fred Hutchison Cancer Research Center in Seattle and colleagues analyzed data from the dietary modification trial to see if the changes in the women’s diets decreased the risk of ovarian and endometrial cancer and invasive cancers overall. In the trial, nearly 20,000 women were randomly assigned to the diet modification group, and almost 30,000 women ate their normal diet. The women participating in the diet were asked to reduce their fat intake to 20 percent of their overall diet, as well as eat at least five serving of fruits and vegetables a day and at least six servings of whole grains. They were followed for an average of eight years.

The risk of ovarian cancer was similar in the two groups for the first four years of follow-up, but it was reduced in the dieting group during the following four years. Women who had the highest fat intake before the trial saw the greatest reduction in risk. There was no difference in endometrial cancer risk between the two groups, but a trend toward a reduction in invasive cancers overall was suggested in the dieting group. It was not statistically significant. “Since the participants saw a protective effect after four years or more, the study speaks to the importance of long-term commitment to healthy eating habits,” says Dr. Thomson. “Ongoing... follow-up of trial participants may provide additional valuable assessment of the effects of a low-fat dietary pattern on these and other cancer incidence rates,” the authors write.

The National Institutes of Health established the Women's Health Initiative (WHI) in 1991 to address the most common causes of death, disability and impaired quality of life in postmenopausal women. The WHI addressed cardiovascular disease, cancer, and osteoporosis. The WHI was a 15-year, multi-million dollar endeavor and one of the largest U.S. prevention studies of its kind, enrolling 161,808 women aged 50-79. Approximately 5,000 Arizona women participated, with Tamsen Bassford, MD, head of the University of Arizona College of Medicine’s Department of Family and Community Medicine, serving as the principal investigator. The three major components of the WHI were a randomized controlled clinical trial of promising but unproven approaches to prevention; an observational study to identify predictors of disease; and a study of community approaches to developing healthy behaviors.

The clinical trial and observational studies were interrelated and conducted at the same 40 clinical centers. Issues addressed included benefits and risks of hormone therapy, changes in dietary patterns, and calcium, vitamin D supplementation in disease prevention. An extension of the WHI observational study and clinical trial began in 2005 and will last until 2010. Dr. Thomson is serving as the principal investigator in Arizona, with 3,680 women currently participating. The Arizona Cancer Center is the state’s premier National Cancer Institute-designated comprehensive cancer center. With primary locations at the University of Arizona in Tucson and Scottsdale Healthcare, the Center has more than a dozen research and education offices throughout the state and 275 physician and scientist members working to prevent and cure cancer. For more information, go to www.arizonacancercenter.org