(AP) – For the first time, a large experiment showed that cutting down on dietary fat and eating more fruits and vegetables could reduce the risk of women dying from breast cancer.
The results were important because they came from a rigorous test involving 49,000 women over two decades rather than other studies that tried to draw health conclusions from observations about how people eat.
Healthy women who modify their diet for at least eight years and who later develop breast cancer have a 21% lower risk of dying from the disease compared to other people who continue to eat as usual.
However, the risk is small to start and the effects of the diet are not large, so it takes 20 years for differences between groups to emerge. Changes in diet also do not reduce the risk of breast cancer, which is the main goal of this study.
Still, doctors say the results show how women can increase their chances of survival.
"Patients really want to do the things they can do," Dr. Jennifer Ligibel from the Dana-Farber Cancer Institute in Boston. "It really shows that changing your diet, losing weight, exercising can actually be a treatment."
He did not have a role in this study, led by Dr. Rowan Chlebowski from the Los Angeles Biomedical Research Institute at the Harbor-UCLA Medical Center. He gave the results Wednesday at a telephone press conference held by the American Society of Clinical Oncology ahead of his annual meeting later this month.
"We need to take this very seriously" because of the quality of the research, said Dr. Lidia Schapira, a breast cancer expert at Stanford University and spokesperson for the oncology community. "What we eat is important."
The results came from the Women 's Health Initiative, a large federal – funded study that had previously overturned old advice about hormone therapy for menopausal symptoms.
The research diet section listed 48,835 women aged 50 to 79 years without breast cancer in the 1990s. At first, they get a third of calories from fat. One group was given regular counseling sessions and was asked to limit fat to 20% of calories and to eat more vegetables, fruits and grains. The rest continued their usual eating habits.
Groups aiming for low fat did not reach the target, but cut fat intake to 24% after one year and around 30% after eight years – still lower than where they started. Fat intake in the comparison group remained almost the same.
Previous research showed that there were fewer deaths from all causes among women in the low fat group who later developed breast cancer. Now, after 20 years, there are also differences in deaths from the disease. However, only 383 women died of breast cancer, so the benefits were absolutely small.
Does this reduce fat or add vegetables, fruits and grains that help?
"Diets are complicated. If someone eats more than one food, they eat less than others," and it's difficult to say which changes do what, Ligibel said. Eating too much starchy food is also not good, and researchers now know that this type of fat is important, and that some fats such as olive oil are better than others.
"Our view of diet has evolved since the study was designed," he said.
Ligibel leads a study to see whether losing weight increases survival for women with early-stage breast cancer. Chlebowski is working on another study to see if women who are obese or have certain other health risks get the greatest benefit from trimming food fat. The results of this study show they are possible.