The study examined the diets of more than 2,400 women between the ages of 48 and 79, who had participated in the Women's Intervention Nutrition Study (WINS), sponsored by the U.S. National Cancer Institute (NCI).
Researchers found that 9.8 percent of conventionally treated post-menopausal women with early-stage breast cancer had a recurrence of their disease after five years when they ate a low-fat diet (33 grams of fat per day). Women who ate a standard diet -- consisting of 52 grams of fat per day -- had a 12.4 percent recurrence rate.
The researchers concluded that women on a low-fat diet experienced a relative cancer recurrence risk reduction of 24 percent, compared to women on a standard diet. However, the greatest reduction in risk -- 42 percent --was found in women on a low-fat diet whose tumors were not responsive to estrogen. Conversely, women on a low-fat diet whose tumors did respond to estrogen reduced their risk by 15 percent.
Breast cancer that does not respond to the presence of estrogen is called estrogen receptor-negative (ER-negative) cancer. Women with ER-positive breast cancer generally have a more positive outcome than ER-negative breast cancer patients.
"Reductions [in risk] were predicted in women with ER-positive disease because of the association between fat intake and estrogen levels," said John Milner, chief of the Nutritional Science Research Group at the NCI, "but the effect on ER-negative disease is, if verified, a surprising and potentially important observation regarding breast cancer and signals a possible new avenue of research."
Natural health advocate Mike Adams, author of "The Healing Power of Sunlight and Vitamin D," noted that the NCI study did not differentiate between types of fat, and encouraged women to avoid animal fats, but consume adequate quantities of nutritious plant-based fats.
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