Ask the Care Team
Does eating a low-fat diet help prevent breast cancer or lead to better outcomes in breast cancer patients?
Animal studies and studies comparing breast cancer rates across the world have found lower rates of breast cancer when diets contain less fat. Does this mean women concerned about breast cancer should sharply curtail their fat intake?
Despite long interest in this question, the answers aren't yet clear.
One encouraging report came in 2005 from the Women's Intervention Nutrition Study, which compared cancer recurrence rates in women randomized to a low-fat or standard diet. After five years of follow-up, 12.4 percent of the standard diet group had had a recurrence, compared with 9.8 percent of women on the low-fat regimen. Women in the reduced-fat group also lost about five pounds in the first year and kept it off for the full five years of follow-up. Preliminary results suggest that the low-fat diet might be even more beneficial in women with estrogen receptor-negative tumors, who have traditionally had a worse prognosis than women with hormone-driven cancers.
"This study suggests that lifestyle changes can have an impact on breast cancer prognosis," says Jennifer Ligibel, MD, an oncologist in Dana-Farber's Women's Cancers Program. "It is not clear whether the improved prognosis was due to the low-fat diet or the weight that women lost as a result of the change in diet, but these findings are incredibly empowering for women with breast cancer because they suggest there are things that women can do for themselves to lower their risk of recurrence."
A much larger trial run by the Women's Health Initiative asked whether decreasing consumption of total fats would help prevent breast cancer. Involving 48,835 cancer-free, postmenopausal women, the study found that women randomized to a low-fat diet did not have a significantly lower risk of developing breast cancer. However, the majority of women on the study never achieved the fat-reduction goal. Some preliminary evidence suggested that the women who did lower their fat intake had a lesser risk of breast cancer.
Eric Winer, MD, director of the Breast Oncology Center, cautions that firm conclusions on this issue require further research and says that women should speak with their healthcare team about dietary issues. He adds, "a woman with breast cancer should try to avoid gaining a significant amount of weight after diagnosis, and those already overweight should try to lose weight if possible."
