Study: Low-Fat Diet May Cut Cancer Risk

This undated handout photo provided by the Fred Hutchinson Cancer Research Center shows Dr. Ross Prentice, interim director and member of the Public Health Sciences Division at Fred Hutchinson Cancer Research Center. (AP Photo/Fred Hutchinson Cancer Research Center) (AP)

WASHINGTON -- Cutting dietary fat may also cut the risk of ovarian cancer, says a study of almost 40,000 older women that found the first hard evidence that menu changes protect against this particularly lethal cancer.

But don't wait too long to get started: The protection didn't kick in until the women had eaten less fat for four years and counting.

Until now, the only known prescription against ovarian cancer _ aside from surgically removing the ovaries _ was to use birth control pills. Use for five years can lower the cancer risk by up to 60 percent, protection that lingers years after pill use ends.

The new findings now offer an option for postmenopausal women to try as well.

Those who followed a low-fat diet for eight years cut their chances of ovarian cancer by 40 percent, researchers reported Tuesday in the Journal of the National Cancer Institute.

"This is really good news," said Dr. Jacques Rossouw of the National Institutes of Health, which funded the work. "But you have to stick with the diet."

It's arguably the most promising finding of the mammoth Women's Health Initiative dietary study, which enrolled tens of thousands of healthy women ages 50 to 79 to track the role of fat in several leading killers. Some women were assigned to cut the total fat in their diets to 20 percent of calories _ from an average of 35 percent _ while others continued their usual diets for comparison.

Yet the study so far has found the diet made little impact on rates of breast cancer, colorectal cancer and heart disease. There are a number of theories: Maybe the women started healthier eating too late; most were overweight, a major risk factor, and the diet wasn't designed to shed pounds. Nor did most women actually cut enough fat.

But despite all those hurdles, a low-fat diet did appear protective against ovarian cancer _ and the women who started with the worst diets and cut fat the most got the most benefit.

Ovarian cancer is fairly rare, affecting one in 60 women compared with the one in 9 who will get breast cancer. But it is among the grimmest of diagnoses, because ovarian cancer usually is detected only after it has spread throughout the abdomen, making it much harder to treat. Only 45 percent of patients survive five years.

The American Cancer Society estimates that 22,430 U.S. women will be diagnosed with ovarian cancer this year; 15,280 women will die of it.

Ovarian cancer can strike anytime in adulthood, but risk increases with age. Mutations in the so-called breast cancer genes BRCA1 and BRCA2 also increase the risk of ovarian cancer _ and women in the new study have not yet been tested for those genes, to see if the low-fat diet proves more or less beneficial for them.