How soy plays a role in breast cancer risk and recurrence is one of the most common questions we get asked. A large body of human research suggests eating tofu, soy milk and other soy foods in moderation safe. Now an animal study that may help explain what is seen in human research, shows that eating soy foods when young boosts the immune response against tumors, reducing cancer recurrence.
The study is being presented at the American Association for Cancer Research (AACR) annual meeting, and is not yet published.
Soy contains compounds called isoflavones that mimic the effect of estrogen. This raised concerns that it would stimulate breast tumors fueled by estrogen and may interfere with anti-estrogen treatment, such as tamoxifen. Early animal studies did find a link between isoflavones increasing risk of breast cancer. According to the news release, one reason may be that this early animal research used animals that do not have certain immune cells called cytotoxic T cells. These are among the cells that act against breast tumors. Continue reading