Starch intake may influence risk for breast cancer recurrence, study suggests

"The results show that it's not just overall carbohydrates, but particularly starch," said Jennifer A. Emond, M.S., a public health doctoral student at the University of California, San Diego. "Women who increased their starch intake over one year were at a much likelier risk for recurring."

Researchers conducted a subset analysis of 2,651 women who participated in the Women's Healthy Eating and Living (WHEL) Dietary Intervention Trial, a plant-based intervention trial that enrolled about 3,088 survivors of breast cancer. WHEL researchers studied breast cancer recurrence and followed the participants for an average of seven years.

The subset analysis involved an examination of how changes in carbohydrate intake influenced breast cancer recurrence. "The WHEL dietary trial, even though it focused on fruits and vegetables, fiber and fat, didn't really have a specific carbohydrate goal," Emond said.

She and her colleagues obtained carbohydrate intake information from multiple 24-hour dietary recalls at baseline and at one year. In an annual phone interview, participants reported everything they had eaten during the last 24 hours. At baseline, carbohydrate intake was 233 grams per day. Results showed that women whose cancer recurred had a mean increase in carbohydrate intake of 2.3 grams per day during the first year, while women whose cancer did not recur reported a mean decrease of 2.7 grams per day during the first year.

Starches were particularly important, Emond said. Changes in starch intake accounted for 48 percent of the change in carbohydrate intake. Mean change in starch intake during the first year was -4.1 grams per day among women whose cancer recurred vs. -8.7 grams per day among women whose cancer did not recur.

When change in starch intake during one year was grouped into quartiles of change, the rate of an additional breast cancer event was 9.7 percent among women who decreased their starch intake the most during one year, compared with an event rate of 14.2 percent among women who increased their starch intake the most during one year.

The change in starch intake was "independent of dietary changes that happened in the intervention arm," Emond said. "It is independent of more global changes in diet quality."

After stratifying patients by tumor grade, Emond and colleagues found that the increased risk was limited to women with lower-grade tumors.

These results indicate a need for more research on dietary recommendations that consider limited starch intake among women with breast cancer.