Although there is a concern regarding the safety of soy food consumption
among breast cancer survivors, researchers have found that women in
China who had breast cancer and a higher intake of soy food had an
associated lower risk of death and breast cancer recurrence, according
to a study in the December 9 issue of JAMA.
"Soy foods are rich in isoflavones, a major group of phytoestrogens
that have been hypothesized to reduce the risk of breast cancer.
However, the estrogen-like effect of isoflavones and the potential
interaction between isoflavones and tamoxifen have led to concern about
soy food consumption among breast cancer patients," the authors write.
Xiao Ou Shu, M.D., Ph.D., of Vanderbilt University Medical Center,
Nashville, Tenn., and colleagues examined the association between soy
isoflavone intake with breast cancer recurrence and survival. The
researchers analyzed data from the Shanghai Breast Cancer Survival
Study, a large, population-based study of 5,042 female breast cancer
survivors in China. Women ages 20 to 75 years with diagnoses of breast
cancer between March 2002 and April 2006 were recruited and followed up
through June 2009. Information on cancer diagnosis and treatment,
lifestyle exposures after cancer diagnosis, and disease progression was
collected at approximately 6 months after cancer diagnosis and was
reassessed at three follow-up interviews conducted at 18, 36, and 60
months after diagnosis. A Shanghai Vital Statistics Registry database
was used to obtain survival information for participants who were lost
to follow-up.