Dec. 16, 2006 (San Antonio) -- Updated results from what researchers call the first study to directly show that lifestyle changes can improve the outlook for people with cancersuggests a low-fat diet can help prevent breast cancerrecurrence.
In the study of more than 2,400 postmenopausal women with early breast cancer, those who cut down on fats in their diet were about one-fifth less likely to either suffer a recurrence or die over the next six to seven years, compared with those who continued to eat their usual foods, according to the updated report.
Women whose tumors were not fueled by hormones -- about 30% of women with breast cancer -- benefited most.
Their chance of recurrence was cut by more than half, and their risk of dying was slashed by two-thirds, says researcher Rowan T. Chlebowski, MD, a medical oncologist at the Los Angeles Biomedical Institute at the Harbor-University of California-Los Angeles Medical Center in Torrance, Calif.
"That's as good or better than any treatment intervention we have for this type of disease," which is notoriously difficult to treat, says C. Kent Osborne, MD, a breast cancer specialist at Baylor College of Medicine in Houston who was not involved with the work.
In contrast, there was little benefit for women with hormone-receptor-positive tumors. The growth of those breast cancers is fueled by hormones; it's the most common type of the disease.
Low-Fat Diet and Breast Cancer
The study, presented here at the San Antonio Breast Cancer Symposium, included 2,437 women aged 48 to 75.
But nearly 1,000 of the women also entered an intensive nutritionprogram, which included eight one-on-one sessions with a dietitian every other week, followed by quarterly visits. There were also monthly support groups.
The dietitian asked patients what they were eating and taught them which foods contained fat and how much fat -- even how to count fat grams. The goal was to reduce dietary fat intake to 20% or less of daily calories, compared with 45% for the average American.
Breast Cancer Risk Cut
The women who received intensive counseling reduced the amount of fat in their diet from 57 grams per day to about 38 grams a day, or from 29% to 19% of their total daily calories.
They were rewarded with a modest amount of weight loss-- shedding about six pounds more than those who continued to eat their typical foods.
By nearly six years later, cancer had recurred in about 11% of those on the low-fat diet, compared with more than 13% of those on their usual diet. That translates to about a 21% relative reduction in risk, Chlebowski says.
Put another way, if 36 women adopted the low-fat diet, there would be one fewer nonfatal relapse, he tells WebMD.
In addition, 10% of the women on the usual diet died, vs. 8% of those on the low-fat plan -- translating to a 22% reduction in risk.
Among the subgroup of women whose cancers were not fueled by hormones, only 6% who counted fat grams died, compared with 17% who followed their usual diet.
For the updated analysis, researchers at all 39 centers participating in the study provided six-year data; 10 centers also offered seven-year data.
What Should a Woman Do?
Researchers say it's too soon to conclude that counting fat grams is the latest weapon in the war on cancercancer. But skipping the cheese and crackers won't hurt -- and might help.
"This is a seminal study that suggests that following a low-fat diet may help prevent relapses, particularly among women with hormone-receptor-negative disease," says Richard Elledge, MD, a breast cancer specialist at Baylor College of Medicine in Houston and co-moderator of the session.
But, Elledge says, breast cancer survivors who have trouble sticking to a low-fat diet should not feel guilty. "This is just one study," he tells WebMD.
Kay Blanchard, MD, a breast surgeon at Baylor College of Medicine in Houston, says reducing fats "has obvious heart health benefits.
"In terms of breast cancer, it may even provide additional benefit," she tells WebMD.
Making the changes is "all about substitution and reduction," Chlebowski says.
Breakfast should be cereal and low-fat milk instead of sweet rolls or baked goods. Snack on popcorn -- not cheese and crackers. Skip the spread on the bread, the salad dressing on the salad. You can still eat meat; just cut down on portion size, he says.
Regular visits with a nutritionist are critical to sticking with the plan long-term, he adds.
More Study Needed
Everyone agrees more study is needed.
For example, researchers can't say with certainty whether it was the low-fat diet, the weight loss, or maybe some other factor -- like an increase in fiber-rich fruits and vegetables -- that should get the credit for the women's better health.
They also don't know why women with hormone-receptor-negative cancer benefited so much and those with hormone-positive cancer benefited so little.
Chlebowski says he and the team he works with plan to look at whether a low-fat diet, combined with weight loss and exercise, can prevent cancer comebacks in women with hormone-receptor-negative cancer. That study should kick off next year.