In recent years, several studies have tried—and failed—to find a link between diet and cancer. A study presented this week at the American Society of Clinical Oncology meeting in Orlando, Fla., tried again.

What the researchers wanted to know: Does eating a low-fat diet reduce the risk that breast cancer will recur?

What they did: Nearly 25,000 women who'd had early-stage breast cancer were recruited for the study. The women, ages 48 to 79, had already gone through menopause. Women were randomly assigned to either a program meant to reduce their fat intake or to more general counseling on eating a balanced diet. Women who were assigned to the dietary intervention met individually with a nutritionist once every two weeks, for a total of eight sessions, to learn how to cut fat out of their diets, then continued meeting with a nutritionist once every three months. The women were followed for several years, to see if their cancer returned. The women on the low-fat diet ate an average of 33.3 grams of fat a day, while the women who were on a standard diet ate an average of 51.3 grams of fat a day.

What they found: In the time that the researchers were able to follow up on the women, 12.4 percent of the women on a standard diet had a recurrence of breast cancer, compared with only 9.8 percent of the women eating a low-fat diet. The benefit seemed to be greater for women who'd had estrogen-receptor-negative cancers, which are less common than estrogen-receptor-positive cancers. The researchers also looked at how many women died and found that women on the low-fat diet were also less likely to die during the follow-up period.

What the study means to you: If you've had breast cancer, you might want to consider reducing fat in your diet. The reduction in risk of cancer recurrence wasn't huge in this study, but nutritionists say you should probably be eating less fat anyway. In any case, it is scientifically interesting to have support for the hypothesis that diet could have an effect on cancer risk.

Caveats: Pinning down cause and effect is difficult in nutrition research, where you're dealing with something as complicated as diet. The researchers don't really know why the women on the low-fat diet were less likely to see their cancer return. It could be because they lost more weight, or alternatively, that they ate more fruits and vegetables than the women on standard diets.

Find out more: The American Cancer Society has information about risk factors for breast cancer—those you can modify, and those you can't.

Read about the potential cancer risks (or benefits) of many different foods and vitamins.

Check out a November study on USNews.com that found eating fruits and vegetables protects against cardiovascular disease, but not cancer.

Abstract online: http://www.asco.org