MONDAY, Oct. 18 (HealthDay News) -- For women past menopause who have had breast cancer, a higher intake of soy may help reduce the risk of the disease's recurrence, a new study of Chinese women suggests.
The same link was not found in premenopausal women with breast cancer, whatever their soy intake, the study authors said.
The study, while called intriguing by U.S. experts, was not large and included only women with breast cancer receiving care in China. It's not known if the results would apply to other groups of women, said Marji McCullough, a spokeswoman for the American Cancer Society.
"Chinese women may have been likely to have a lifelong high consumption of soy," she said. "We don't know whether starting on a diet high in soy after a breast cancer diagnosis would have the same effect as eating a lifelong diet high in soy."
For the study, Dr. Qingyuan Zhang of the Cancer Hospital of Harbin Medical University in Harbin, China, evaluated 524 women who had undergone breast cancer surgery between August 2002 and July 2003. They were receiving endocrine therapy such as anastrozole (Arimidex) or tamoxifen to reduce cancer recurrence risk.
The researchers measured the women's dietary intake of soy isoflavones at the start of the study, and then followed them for about five years to see if breast cancer recurred.
For the premenopausal women, soy had no apparent effect on the risk of subsequent breast cancer.
But postmenopausal women with the highest intake of soy -- more than 42.3 milligrams of soy isoflavones a day -- had a 33 percent reduced risk of cancer recurrence. For patients receiving anastrozole and whose breast cancer was estrogen receptor-positive and progesterone receptor-positive, the risk reduction link was even stronger.
The study findings were published Oct. 18 in CMAJ (the Canadian Medical Association Journal).
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