A diet loaded with fruits, vegetables and fiber compared to standard federal dietary recommendations cuts the risk of breast cancer recurrence - in women without hot flashes - by approximately 31 percent, according to a new study.
These patients typically have higher recurrence and lower survival rates than breast cancer patients who have hot flashes.
The study was led by researchers at the Moores Cancer Center at the University of California, San Diego, along with six other sites, including the University of California, Davis.
"Our interest in looking at this subgroup came because hot flashes are associated with lower circulating estrogen levels, while the absence of hot flashes is associated with higher estrogen levels.
Reducing the effect of estrogen is a major treatment strategy in breast cancer," said the WHEL study principal investigator John P. Pierce, Ph.D., Sam M. Walton Professor for Cancer Prevention and director of Cancer Prevention and Control at the UC San Diego School of Medicine and the Moores UCSD Cancer Center.
"It appears that a dietary pattern high in fruits, vegetables and fiber, which has been shown to reduce circulating estrogen levels, may only be important among women with circulating estrogen levels above a certain threshold," he added.
About 30 percent of the original group of 3,088 breast cancer survivors did not report hot flashes at study entry.
The women had been randomly assigned to one of the two diets between 1995 and 2000 and were followed until 2006.
About one-half (447) of the "no hot flashes" group were randomized to the special, "intervention" high-vegetable fruit diet while the other half (453) was given the generally recommended diet of five servings of fruits and vegetables a day.
The team found that those on the intervention diet had a significantly lower rate of a second breast cancer event (16.1 percent) compared to those eating the government-recommended five-a-day dietary pattern (23.6 percent).
The dietary effect was even larger (a 47 percent lower risk) in women who had been through menopause.
The study appears online December 15, 2008, in the Journal of Clinical Oncology.