Fat poses dual threat of breast cancer.

Fat poses dual threat of breast cancer

Dozens of studies suggest that fatty foods may predispose women to breast cancer. Others suggest that the large number of clories typically consumed in ahigh-fat diet may represent the real underlying risk. In an attempt to settle the controversy, three National Cancer Institute researchers have reanalyzed 100 animal experiments, in many cases pooling data from various studies before hunting for statistical trends. In the Sept. 15 CANCER RESEARCH, they conclude that both fat and calories pose independent breast cancer risks.

"The calorie effect was stronger than the fat effect," says biostatistician Laurence S. Freedman, who led the study. The data suggest that every excess calorie raises breast cancer risk, with each excess fat-derived calorie posing about 67 percent more risk than calories from other sources, he says.

A study of Finnish women, described in the November AMERICAN JOURNAL OF CLINICAL NUTRITION, appears to support a fat-relted risk. The researchers analyzed dietary questionnaires filled out at least 20 years ago by 3,988 healthy women aged 20 to 69, and found that the 54 participants who later developed breast cancer showed a "consistently higher" average percentage of fat-derived calories. Dividing the entire sample into thirds based on the proportion of fat in the women's diets, they calculated that the subgroup eating the most fat had a breast cancer risk about 70 percent higher than the subgroup eating the least fat.

Demetrius Alanes of the National Cancer Institute, who coauthored the Finnish study, says he wasn't surprised that no independent risk from calorie showed up, since the study involved relatively few cancer cases and lcked exercise data, and since the cancer and noncancer groups had similar height-to-weight ratios. However, he says, the results did turn up hints that diets high in carbohydrates or milk might lower breast cancer risk by as much as 60 percent.