Diets’ impact on cancer spurs critics

ORLANDO, Fla. – A new study seems to suggest low-fat diets can help prevent a return of breast cancer in certain women, but many specialists say other factors might have played a role.

The report created a buzz at a meeting of the American Society of Clinical Oncology, where it was presented Monday. Many previous studies have failed to find that cutting fat in the diet can prevent breast cancer, so some doctors urged caution on the new data.

The study was funded by the National Cancer Institute and involved 2,437 women at 37 sites around the country.

All had surgery followed by standard chemotherapy drugs for early-stage breast cancer and five years of tamoxifen if their tumors were helped to grow by estrogen. As a group, 29 percent of their calories came from fat, far lower than the typical American who gets up to half of calories from fat, according to what the women told doctors at the outset of the study.

Doctors told 1,462 to continue normal diets. The other 975 were given counseling to help them cut fat and track what they ate. The low-fat group averaged 33.3 grams of fat a day compared to 51.3 grams for the others.

Five years later, the cancer had returned in 9.8 percent of those on the low-fat diet versus 12.4 percent of those on standard diets, said Dr. Rowan Chlebowski of Los Angeles Biomedical Research Institute, who led the study. This was a 24 percent lower risk as a whole.

The only women who benefited were those whose tumors weren’t helped to grow by estrogen. They had 42 percent lower risk of recurrence if they ate low-fat diets but accounted for just 1 out of 5 women in the study – similar to breast cancer cases in the general population.

Results for the other 4 out of 5 women did not reach statistical significance, meaning they could have occurred by chance alone – a point the American Cancer Society noted in a statement posted on its Web site Monday.