(AP) – For the first time, a large experiment shows that cutting dietary fat and eating more fruits and vegetables can reduce the risk of a woman dying from breast cancer.
The results are remarkable as they come from a rigorous test involving 49,000 women over two decades and not from other studies that try to make health outcomes from observations on how people eat.
Healthy women who changed their diet for at least eight years and who later developed breast cancer had a 21% lower risk of dying from the disease than others who continued to eat as usual.
However, this risk was small to start and the effect of the diet was not huge, so it took 20 years for the difference between the groups to appear. Changing the diet also does not reduce the risk of developing breast cancer, which is the main goal of the study.
Still, doctors say the results show a way women can improve their chances of survival.
"Patients are eager for things they can do," said Dr. Jennifer Ligibel of the Dana-Farber Cancer Institute in Boston. "It really suggests that changing diet, weight loss, exercise can actually be a cure."
She had no role in the research led by Dr. Rowan Chlebowski of the Los Angeles Biomedical Research Institute at the Harbor-UCLA Medical Center. He delivered results Wednesday at a telephone press conference held by the American Society of Clinical Oncology before the annual meeting to be held later this month.
"We have to take this very seriously" because of the quality of the study, said Dr. Lydia Shapira, Stanford University Breast Cancer Expert, and spokeswoman for the oncology community. "What we eat is important.
The results come from the Women's Health Initiative, a large federal-funded study that has previously overlooked long-standing hormonal therapy tips for menopausal symptoms.
In the diet part of the study included 48,835 women aged 50 to 79 years without breast cancer in the 1990s. At first they started receiving one third of the calories from the fat. A group receives regular counseling sessions and is told to limit the fat to 20% of the calories and to eat more vegetables, fruits and grains. Others continue their usual eating habits.
The low fat group missed the goal but reduced fat intake to 24% after one year and about 30% after eight years – still lower than where they started. Fat acceptance in the comparator group remained roughly the same.
The study previously showed that among women in the low-fat group who later developed breast cancer, there were fewer deaths for all causes. Now, in 20 years, there is also a difference in mortality from this disease. However, only 383 women died of breast cancer, so the benefit in absolute terms is small.
Was it helping to cut fat or increase vegetables, fruits and grains?
"If you eat more than one meal, they eat less than another," and it's hard to tell what change that is, Ligibel said. Eating too much starch is not good, and researchers already know that the type of fat is important and that some fats like olive oil are better than others.
"Our view of the diet has evolved since this study was designed," she said.
Ligibel is leading a study to see if weight loss improves survival in women with early breast cancer. Chlebowski is working on another study to see if women who are overweight or have some other health risks get the most benefit from cutting dietary fat. The results of this study show that they could.