Soy foods no risk for breast cancer survivors

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After years of confusion about the safety of the food intake of breast cancer survivors soy, a large new study found that eating soy foods increases not the risk of cancer recurrence or death among breast cancer survivors. The study was introduced annual meeting in Orlando, Florida at the American Association for cancer research (AACR).

Investigators from several research institutes in the United States and China examined the association between soya food intake and breast cancer results, with data from the following breast cancer pooling project, a multi-institution collaborative study.

"There has been concern about the safety of soy products for women with breast cancer," Vanderbilt - Ingram Cancer Center (VICC) said lead investigator Xiao OU Shu, m.d., PhD., Professor of medicine.

"Soy foods contain large amounts of isoflavones, which are known to have an impact on estrogen receptors in the cells to bind and estrogen-like and estrogen-active."

Estrogen is a hormone, was linked cancer growth in breast cancer. The tumors are found tamoxifen are often treated with the estrogen Blocker medication to estrogen receptor positive breast cancer patients.

"There are concerns, the effect of tamoxifen isoflavone increase the risk of recurrence in patients with breast cancer cancer can by compromising because tamoxifen and isoflavones bind to estrogen receptors," Shu said.

To resolve these problems, the investigators pooled data from three prospective cohorts of patients with breast cancer: life after cancer epidemiology (LACE); Women's healthy food and life study (wave HORN), both in the United States; and the Shanghai breast cancer survival study (SBCSS) in Shanghai, China.

The study included 9,515 patients with breast cancer, the food estimate frequency questionnaires, what types of foods including soya products such as tofu, they ate, sprouts, soy milk, cooked soybeans, miso soup, soy beans and breakfast/protein shakes answered with extra soy.

The U.S. studies evaluated this soy foods often by U.S. women consumed and the China study used a validated soy questionnaire for women in Shanghai. The two most important soy products, which were all studies are tofu and soy milk. The average daily soy isoflavone intake among U.S. women was 3.2 mg. The amount was significantly higher in the Shanghai Group, 45.9 mg.

Soy isoflavones was rated 14.6 months after diagnosis of breast cancer and the average follow-up time was about 7.4 years after diagnosis.

Women who ate the most soy foods, at more than 11.83 mg of isoflavones per day, was a 27 percent reduced risk of breast cancer recurrence, compared to the one with the lowest intake (3.68 mg per day or less). High soy food intake was also associated with a slightly reduced risk of mortality, although this has achieved results not statistically significant.

"Our results show that it helpful can be included for women as part of a healthy diet, soy foods, even if they have breast cancer," said Shu. "This may not directly generalized additions to soy, however, as supplements of soy products in the types and quantities of isoflavones can be different."

Women can get the extent of soy isoflavones, the highest consumption by eating a cup of soy milk or two ounces of tofu per day in the US population study found similar.

Sarah Nechuta, PhD, MPH, postdoctoral fellow at the VICC, is first author of the study, the researchers at Kaiser Permanente, Oakland, California, Brigham and women's Hospital, Harvard Medical School and the Dana-Farber Cancer Institute, Boston, Massachusetts, Moores UCSD cancer CenterUniversity of California, San Diego, and the Shanghai Center for disease control and prevention, Shanghai, China.

The research was by the American recovery and Reinvestment Act of 2009, the resources of several National Cancer Institute funded studies combined funded.

Source:
Vanderbilt - Ingram Cancer Center