eating

Soy: Latest Study Shows No Increase in Breast Cancer Risk

PJ Hamel Health Guide August 03, 2012
  • For years, women (and their doctors) have been confused about the link between soy products and breast cancer. As a survivor, is it OK to eat tofu and drink soy milk… or not? The latest soy/breast cancer study, released in May, shows no apparent negative connection between soy and breast cancer.   
     
    “My doctor says that my breast cancer is estrogen-receptive. And since soy products include phytoestrogens, if I want to lower my risk of recurrence, I should avoid soy milk and tofu.”

    “I was treated for estrogen-receptive breast cancer. And my doctor says there’s no evidence that consuming soy increases my risk of recurrence, so I can go ahead and enjoy my veggie burgers.”


    Two doctors; two opinions.

    Which doctor is right? Does eating soy increase your risk of breast cancer recurrence, or not?

    For years, researchers have been unable to offer a clear answer to that question. And, since oncologists always err on the side of caution when it comes to anything that might increase your risk of recurrence, most have advised their patients to avoid soy – “just in case.”

    However, with increasing numbers of Americans eating and enjoying soy-based products – everything from soy coffee creamer to Soy Dream ice cream – determining if there’s a soy/breast cancer connection had become more and more critical.

    Now, two major studies, stretching back over 20 years, have revealed surprising results: not only is there no evidence that soy consumption increases the risk of breast cancer recurrence, it appears that women consuming soy products actually lower their risk of recurrence slightly.

    A May 30 article in The American Journal of Clinical Nutrition, detailing results of two long-term studies, concludes that “postdiagnosis soy food consumption of ≥10 mg isoflavones/d was associated with a nonsignificant reduced risk of breast cancer–specific mortality and a statistically significant reduced risk of recurrence. “ (Nechuta, 2012)

    Translation? While eating soy doesn’t seem to lower your risk of death from breast cancer, it does seem to reduce your risk of recurrence.

    Now that’s a far cry from the “soy has phytoestrogens, estrogen increases your risk of recurrence, don’t eat soy” message we’ve been hearing for years.

    How could the science seem to change so dramatically?

    Past studies have shown that the plant estrogens in soy products stimulate the growth of breast cancer cells – in the lab, in a petri dish. (Limer, 2004). This was the information your doctor was using when s/he told you it would be best to avoid soy.

    But as it turns out, the results of those older lab studies never translated to breast cancer survivors drinking soy milk or eating tofu.

    The just-released Nechuta study followed survivors from 1991 to 2006 – tracking soy consumption, and noting deaths and recurrences in the study population.

    And, 6 years after the close of the study, researchers feel confident that they have a clear answer to the soy/breast cancer connection: the lab experiment didn’t translate to real life.


  • Soy is OK for breast cancer survivors – and may even be beneficial.


    Why the “may”? Because these recent study results are what they call “correlative” – the exact connection between soy and breast cancer hasn’t been identified.

    But there’s evidence that increased consumption of soy lowers breast cancer recurrence – even if scientists don’t know why.

    Bottom line for survivors: if you eat soy, enjoy. If you don’t, it may be one more thing to consider – along with exercise and weight control – as you create a healthy lifestyle, one that will hopefully keep cancer at bay.

    Sources

    O'Connor, A. (2012, June 25). Really? Eating soy increases the risk of breast cancer. Retrieved from http://well.blogs.nytimes.com/2012/06/25/really-eating-soy-increases-the-risk-of-breast-cancer/

    Nechuta, S. et. al. (2012, May 30). 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. Retrieved from http://www.ajcn.org/content/96/1/123.abstract?etoc

    Limer, J. (2004, March 18). Phyto-oestrogens and breast cancer chemoprevention.. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/15084232