Diet May Cut Risk Of Cancer Recurring

After an average of five years, 96 women on the low-fat diet -- 9.8 percent -- had had a recurrence of cancer, compared with 181 -- 12.4 percent -- of those on a standard diet. That amounted to a 24 percent reduction in risk on the low-fat diet.

Surprisingly, the risk reduction was even greater for women whose cancers were not sensitive to the hormone estrogen. Their risk fell by about 42 percent. That finding was especially encouraging because those women have no other way to reduce the risk of a recurrence. Women whose cancers are sensitive to estrogen can take hormone-blocking drugs such as tamoxifen, which lowers their risk by about the same amount.

Chlebowski noted that the diet tested in the study was designed to be practical for most people.

"It doesn't require eliminating meat from the diet or any drastic steps. It's mostly just substituting one food for another -- like eating cereal in the morning instead of a sweet roll for breakfast, cutting back on butter on bread and reducing portion sizes," he said in a telephone interview.

Researchers are uncertain why low-fat diets might reduce the risk of recurrence, but reducing fat in the diet may cut the amount of the hormone insulin in the blood, Chlebowski said. In addition to controlling blood sugar levels, insulin may also promote cancer growth.

Other researchers questioned whether the study adequately accounted for other changes that may have played a role, such as whether the women on the low-fat diets lost weight, ate more fruits and vegetables, exercised more or reduced their overall caloric intake.

Chlebowski acknowledged that the women in the study who cut their fat intake lost about four pounds on average, and probably consumed more fruits and vegetables. But they did not increase their exercise significantly or sharply reduce overall caloric intake, he said.

"The point is, if you do this intervention, this is the result you apparently get," Chlebowski said. "So in that way the exact mechanism isn't important."