Low-fat 'prevents breast cancer'
2005-05-17 14:53
Orlando - A new study seems to suggest low-fat diets can help prevent a return of breast cancer in certain women, but many specialists disagreed with the conclusions, saying other factors might have played a role.
The report created a buzz at the world's largest cancer meeting, the American Society of Clinical Oncology, where it was presented on Monday.
Many previous studies have failed to find cutting fat in the diet can prevent breast cancer, so some doctors urged caution in interpreting the new information.
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 tumours were oestrogen-receptor positive — that is, helped to grow by oestrogen.
As a group, 29% of their calories came from fat, already far lower than the typical American who gets up to half of calories from fat.
Doctors told 1 462 of them to continue their normal diets. The other 975 were given intensive counselling — eight personal, biweekly sessions with a dietician at the outset and follow-ups every three months — 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% of those on standard diets, said Dr Rowan Chlebowski of Los Angeles Biomedical Research Institute, who led the study. This translated to a 24% lower risk for the group as a whole.
Not all results statistically significant
However, the only women who benefited were those whose tumours were not helped to grow by oestrogen. These women had 42% lower risk of recurrence if they ate low-fat diets, but they accounted for just 1 out of 5 women in the entire study —similar to breast cancer cases in the general population.
Results for the other 4 out of 5 women in the study 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 on Monday.
The advice to follow a low-fat diet to prevent breast cancer "is not something that can be taken generally" from this study's results, said the cancer society's deputy medical director, Dr Len Lichtenfeld.
Many studies have linked excess weight to excess breast cancer risk. The low-fat dieters also likely ate more fruits and vegetables and less red meat — other things known to lower breast cancer risk.
Studies also suggest exercise helps prevent breast cancer.
Breast cancer is the most common non-skin cancer in American women. About 213 000 new cases and 40 870 deaths are expected in the United States this year, and about 1.15 million cases and 411 000 deaths worldwide.
- AP