Low-Fat Diet May Cut Return of Breast Cancer

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Lifestyle changes can improve the outlook for people with cancer. Postmenopausal breast cancer survivors who cut down on fats in their diet can reduce their risk of tumor recurrence, researchers say.

In a study of more than 2,400 women with early breast cancer, those who adopted a low-fat diet were one-fourth less likely to have their cancer return within five years than those who continued to eat their typical foods.

The study was presented at the annual meeting of the American Society of Clinical Oncology.

Researcher Rowan T. Chlebowski, MD, of the Harbor-UCLA Medical Center in Los Angeles, cautions that "this is just a first, strong signal" that dietary changes may help prevent cancer from returning. But if confirmed in future studies, counting grams of fat could become a powerful new weapon in the war on cancer, researchers say.

Dietary fats have been linked to some of the most common cancers including breast, colon, and prostate cancers. According to the National Cancer Institute, limiting fat consumption and calorie intake appears to be one possible strategy to decrease the risk of some cancers. That's because people who eat large amounts of meat, which is high in fat and calories, exhibit an increased cancer risk, especially for colon cancer.

Nutrition Counseling Brings Results

The study included 2,437 women aged 48 to 75. All were treated with surgery for breast cancer, followed by radiation, chemotherapy, and hormone treatment, if needed. Every three months, they received some general dietary guidance.

Nearly 1,000 of the women were also entered into an intensive nutrition program, 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, the amount of fat in those foods, and how to count grams of fat. The goal was to reduce dietary fat intake to 20 percent or less of the total daily calories.

Women who received the intensive counseling reduced the amount of fat in their diet from 51 grams per day to about 33 grams a day, or from 29 percent to 21 percent of their total daily calories.

They were rewarded with a modest amount of weight loss — about 4 pounds.

The women in the other group, on the other hand, did not significantly change their fat intake and their weight remained stable.

Cancer Reduction With Dietary Changes

At five years, less than 10 percent of those on the low-fat diet had their cancer recur. Twelve percent of the women who continued on their usual diet had cancer recurrence during this time. This translates to about a 24 percent reduction in risk, Chlebowski says.

Most breast cancers are fueled by estrogen, and because of this several treatments are available that block hormones to the breast and reduce the risk of recurrence.

Women whose tumors were not fueled by hormones — a high-risk group that account for about 30 percent of women with breast cancer — benefited the most. Their chances of recurrence fell by about 42 percent when limiting dietary fats.

Breast cancer is the second biggest cancer killer of women in the industrialized world, after lung cancer. It kills about 40,000 women each year in the U.S.

What Should a Woman Do?

Everyone agrees that more study is needed. For example, researchers can't say with any degree of certainty whether it was the low-fat diet, the weight loss, or another factor — like an increase in fiber-rich fruits and veggies — that should get the credit for the women's better health. Plus, it's rare to make recommendations based on one study alone.

But the findings are part of a growing body of work showing that diet matters, says Bruce E. Johnson, MD, of the Dana-Farber Cancer Institute and a spokesman for the American Society of Clinical Oncology.

"It can't hurt to let women know that if they cut down on fat, they can cut their chances of recurrence," he tells WebMD.

But Eric Winer, MD, a breast cancer specialist at Harvard Medical School, says until further studies are done, "We don't think we have strong enough evidence that a low-fat diet is going to change outcome."

Though he says he is all for helping his patients lower their chance of relapse, "you don't want every woman with breast cancer to feel like she is damaging her health if she has an ice cream cone."

Chlebowski says making the changes isn't all that difficult. "Largely we're talking about learning how to substitute," he tells WebMD. The women cut out butter, margarine, and salad dressing, and ate cereal instead of baked goods. They eliminated chips, opting for fruits and popcorn instead. They still ate red meat but were told how to cut down on portion size, he says.

The bottom line, Chlebowski says, is that eating less fat and more fruits and vegetables certainly won't hurt women and will probably help — a lot more than was previously thought.

By Charlene Laino, reviewed by Brunilda Nazario, MD

SOURCES: 41st Annual Meeting of the American Society of Clinical Oncology, Orlando, Fla., May 13-17, 2005. Rowan T. Chlebowski, MD, Harbor-UCLA Medical Center, Los Angeles. Bruce E. Johnson, MD, spokesman, American Society of Clinical Oncology; Dana-Farber Cancer Institute, Boston. Eric Winer, MD, department of medical oncology, Harvard Medical School.