A large study of middle-age women with a wide range of fat in their diet shows that eating a high-fat diet raises the risk of developing invasive breast cancer.
The findings, reported in the Journal of the National Cancer Institute, stem from the National Institutes of Health-AARP Diet and Health Study, in which 188,736 postmenopausal women reported detailed information on their diet in the mid-1990s.
During an average follow-up of 4.4 years, 3501 women developed breast cancer.
Based on responses to a 124-item "food frequency" questionnaire, researchers found that women who got 40 percent of their calories from fat had about a 15 percent increased risk of developing breast cancer compared with women got 20 percent of their calories from fat.
Using a more precise 24-hour dietary recall questionnaire, "we found a 32-percent increased risk of breast cancer" among women with a high level of fats in their diet, study chief Dr. Anne C. M. Thiebaut from the National Cancer Institute in Bethesda, Maryland, noted in a telephone interview with Reuters Health.
The increased risk of breast cancer associated with a high-fat diet was seen for all types of fat (saturated, monounsaturated and polyunsaturated) and seemed to be confined to women who were not using hormone replacement therapy at the start of the study.
The suggestion that hormone therapy mediates the association between dietary fat intake and risk of breast cancer should be studied further, the authors suggest.
Thiebaut noted that "other studies have also found these associations; the higher the fat intake, the higher your risk for breast cancer." Nonetheless, there is ongoing debate about the association between dietary fat and the risk of breast cancer, she noted.
In a commentary on the study, two researchers from Harvard School of Public Health in Boston think that focusing on controlling body fat, rather than fat intake, would be more effective in preventing breast cancer.
The "modest associations" that have been observed between high-fat diets and increased breast cancer risk "stand in sharp contrast to the robust evidence for a strong link between (body fat) and the risk of postmenopausal breast cancer," write Drs. Stephanie Smith-Warner and Meir Stampfer.
SOURCE: Journal of the National Cancer Institute, March 21, 2007.
