Soy based foods for estrogen receptor positive cancers

Clementine_P

Hi all,

I recently asked a question to the cancer nutritional expert on Livestrong.  I thought the question and answer may be interesting to those of us with estrogen receptor positive cancers.

My question:

I had an estrogen receptor positive cancer. While my oncologist has not weighed in on this, I have heard many people say that I should stay away from soy products. As a vegetarian, I do rely upon soy products for my protein and I know how good they are for your diet generally. Is there definitive knowledge that eating soy products could be dangerous for those of us with estrogen receptor positive cancers?

The answer:

Melissa Mouton

Hi! Great question. I get this one alot! No, there is not definitive evidence that eating soy is dangerous for those with estrogen receptor positive (or negative) cancers. In fact, the evidence points more towards a protective role of soy with regards to breast cancer (other estrogen sensitive cancer such as ovarian have not been studied as much with regards to soy). Overall, the research is not yet clear, but much of the controversy surrounding soy intake has stemmed from a couple of old in-vitro (test-tube) studies that demonstrated estrogenic activity when isolated soy protein (a very processed product added to some food products like energy bars) was added to breast tissue cells in the laboratory. Based on these limited studies, it became common for physicians to recommend that their breast cancer patients avoid soy intake of any kind. More recent studies have been conducted taking a look at actual breast cancer patients and have suggested that soy intake may play more of a protective role in breast cancer survival. In addition to those studies, it is worth noting that population based studies indicate an inverse relationship with soy intake and breast cancer risk. For example, populations that have higher whole soy food intake tend to have lower risk of breast (and prostate) cancer. Some researchers have proposed the mechanism for this may be the binding of soy isoflavones (considered “weak” estrogens) to estrogen receptors in breast tissue, which blocks the binding of human estrogen to the receptors and thereby preventing the adverse stimulation of these receptors. Until more research is available, several major cancer treatment centers recommend breast cancer patients avoid extremely high intake of soy products and if desired choose a moderate amount of whole soy foods (such as edamame, tempeh, tofu) versus processed soy products. Moderate intake is considered 2 to 3 servings per day. References: Wu, A. H., Yu, M. C., Tseng, C. C., & Pike, M. C. (2008). Epidemiology of soy exposures and breast cancer risk. Journal of Breast Cancer, 98, 9-14. Shu, X. O., Zheng, Y., Cai, H., Gu, K., Chen, Z., Zheng, W., & Lu, W. (2009). Soy food intake and breast cancer survival. The Journal of the American Medial Association, 302(22), 2437-2443. Kang, X., Zhang, Q., Wang, S., Huang, X., & Jin, S. (2010). Effect of soy isoflavones on breast cancer recurrence and death for patients receiving adjuvant endocrine therapy. Canadian Medical Association Journal, 182(17), 1857-1862. Magee, P. J., & Rowland, I. (2012). Soy products in the management of breast cancer. Current Opinion in Clinical Nutrition and Metabolic Care, 15(6), 586-591. Nechuta, S. J., Caan, B. J., Chen, W. Y., Lu, W., Chen, Z., Kwan, M. L., Flatt, S. W., Zheng, Y., Zheng, W., Pierece, J. P., & Shu, X. O. (2012). Soy food intake after diagnosis of breast cancer and survival: an in-depth analysis of combined evidence from cohort studies of US and Chinese women. Nutrition and Cancer, 64(5), 652-665. Kang, H. B., Zhang, Y. F., Yang, J. D., & Lu, K. L. (2012). Study on soy isoflavone consumption and risk of breast cancer and survival. Asian Pacific Journal of Cancer Prevention, 13(3), 995-998. Zhang, Y. F., Kang, H. B., Li, B. L., Zhang, R. M. (2012). Positive effects of soy isoflavone food on survival of breast cancer patients in China. Asian Pacific Journal of Cancer Prevention, 13(2), 479-482. MD Anderson Cancer Center. (2013). A healthier diet for cancer survivors. Retrieved from http://www2.mdanderson.org/cancerwise/2013/08/healthier-diet-for-cancer-survivors.htmlDana-Farber Cancer Institute. (2011). Is eating soy safe for breast cancer patients and survivors? Retrieved from http://www.dana-farber.org/Newsroom/News-Releases/Is-eating-soy-safe-for-breast-cancer-patients-and-survivors-.aspxSeattle Cancer Care Alliance. (2013). Women’s Wellness Clinic Newsletter. Safe to enjoy soy. Retrieved from http://www.seattlecca.org/client/WWC_Newsletter_Summer-2013-FINAL-web.pdf

 

Best,

Clementine

1surfermom

Soy vey

Thanks for the information. I just started a diet and a major component of it requires protein drinks. So I guess the take away is that whole soy products are good and processed soy the kind in protein drinks and just about anything else is bad? I suppose  the less processed our food is the better it is for us.  Thanks again for the info.Love Surf

Double Whammy

1surfermom said:

Soy vey

Thanks for the information. I just started a diet and a major component of it requires protein drinks. So I guess the take away is that whole soy products are good and processed soy the kind in protein drinks and just about anything else is bad? I suppose  the less processed our food is the better it is for us.  Thanks again for the info.Love Surf

Thank you, Clementine

I asked my onocologist about this when I was first diagnosed and her response was pretty much what you've shared with us.  I'm not vegetarian, so protein is not an issue for me.  I am conscious of eating soy, but I would not say that I avoid it.  There is soy is so many packaged (processed) foods and I do avoid them, but not because of the soy. 

Thanks again.

Suzanne

bashfulmolly

Staying Away

from processed products is wise for us all and more important for those of us who have or had cancer.I had stage 2 ER+ cancer and I absolutely stay away from soy as there is no definitive answer to this question.I diligently read all ingredients lists and as a result  have eliminated most processed foods.I cook from scratch with fresh ingredients. If I were a vegetarian ,I would get my protein elsewhere..quinoa,beans,tofu,nuts, comes to mind off the top of my head.