Soy & Breast Cancer Survival

Soy & Breast Cancer Survival
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To prevent a recurrence, should breast cancer survivors on Tamoxifen seek, or snub, soy?

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Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

We’ve known for years that soy helps prevent breast cancer, and that evidence continues to grow. And the earlier we can get our daughters to eat soy, the better, as that’s where we see the strongest protection.

If you remember from my Volume 2 DVD, we learned that women who have breast cancer who eat soy live significantly longer. But what if you’re on Tamoxifen—a drug breast cancer survivors can take to help prevent a recurrence, by blocking the effect of estrogen on the body? So if you’re trying to wipe out all trace of estrogen activity, do you want to be eating the phytoestrogens found in soy? Fact or fiction: breast cancer survivors on Tamoxifen should avoid soy. Fiction.

In the Life After Cancer study, following nearly 2,000 breast cancer survivors, women on Tamoxifen who ate the most soy had a 60% reduction in breast cancer recurrence compared to women who ate the least amount of soy phytoestrogens. They cut their risk of cancer coming back in half, just by eating soy.

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Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

We’ve known for years that soy helps prevent breast cancer, and that evidence continues to grow. And the earlier we can get our daughters to eat soy, the better, as that’s where we see the strongest protection.

If you remember from my Volume 2 DVD, we learned that women who have breast cancer who eat soy live significantly longer. But what if you’re on Tamoxifen—a drug breast cancer survivors can take to help prevent a recurrence, by blocking the effect of estrogen on the body? So if you’re trying to wipe out all trace of estrogen activity, do you want to be eating the phytoestrogens found in soy? Fact or fiction: breast cancer survivors on Tamoxifen should avoid soy. Fiction.

In the Life After Cancer study, following nearly 2,000 breast cancer survivors, women on Tamoxifen who ate the most soy had a 60% reduction in breast cancer recurrence compared to women who ate the least amount of soy phytoestrogens. They cut their risk of cancer coming back in half, just by eating soy.

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Doctor's Note

For more on breast cancer risk, check out these videos:
Can Flax Seeds Help Prevent Breast Cancer?
BRCA Breast Cancer Genes & Soy
Breast Cancer & Constipation
Cholesterol Feeds Breast Cancer Cells
Statin Cholesterol Drugs & Invasive Breast Cancer

And check out my other videos on breast cancer

For more context, also see my associated blog posts: Breast Cancer & DietSoy & Breast Cancer: an update; and Soy milk: shake it up! 

If you haven’t yet, you can subscribe to my videos for free by clicking here.

24 responses to “Soy & Breast Cancer Survival

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  1. This is what I am curious about. Does soy lower estradiol and estrone? Or does it act more like DIM and work for a better balance. Isn’t estradiol heart protective, helping memory, blood sugar, etc……while estrone makes ya gain weight, etc…..?? I thought that you wanted the estradiol to be at least twice that of the estrone. If soy increases estradiol then I will Throw a party. And isn’t bioidentical estrogen made from soy, I mean prescription estrogen that is not made from a drug company. So in that case, the soy is used to boost estrogen, but the happy estrogen. I go back and forth on soy because I don’t really understand what it does to the sex hormones and the LAST thing I want to do is to lower my happy estrogen. I do have to say that we cooked two pounds of tofu after the video that soy made ya skinny. :)

    1. I know of no good scientific articles on the adverse effects of soy. Looking into Dr. Mercola’s background and claims should be enough to avoid following his recommendations.

    1. Err… didn’t you notice that just below the video there is a section with Sources Cited? (with links to the studies)

      Everything presented is based on studies. In this case:

      S.
      A. Lee, X. O. Shu, H. Li, G. Yang, H. Cai, W. Wen, B. T. Ji, J. Gao, Y.
      T. Gao, and W. Zheng. Adolescent and adult soy food intake and breast
      cancer risk: Results from the shanghai women’s health study. Am. J.
      Clin. Nutr., 89(6):1920-1926, 2009.

      L. A. Korde, A. H. Wu, T. Fears, A. M. Y. Nomura, D. W. West, L. N.
      Kolonel, M. C. Pike, R. N. Hoover, and R. G. Ziegler. Childhood soy
      intake and breast cancer risk in Asian American women. Cancer
      Epidemiology Biomarkers & Prevention, 18(4):1050, 2009.

      B.N. Fink, S.E. Steck, M.S. Wolff, J.A. Britton, G.C. Kabat, M.M.
      Gaudet, P.E. Abrahamson, P. Bell, J.C. Schroeder, S.L. Teitelbaum, A.I.
      Neugut, & M.D. Gammon. Dietary flavonoid intake and breast cancer
      survival among women on Long Island. Cancer Epidemiol Biomarkers Prev,
      16(11):2285-2292, 2007.

      N. Guha, M. L. Kwan, C. P. Quesenberry Jr, E. K. Weltzien, A. L.
      Castillo, and B. J. Caan. Soy isoavones and risk of cancer recurrence in
      a cohort of breast cancer survivors: The life after cancer epidemiology
      study. Breast Cancer Res. Treat., 118(2):395-405, 2009.

  2. I am well confused about eating soya when having a cancer….i have found many articles which suggest that eating soya reduces the risk of cancer coming back and increases survival rate etc…but there is also the whole lot of articles uploaded recently that suggest that although soya can reduce the risk of getting a cancer it is not recomender for people who already have one becuase of that thingy similar to estrogen…my mum has breast cancer…should she avoid soya or should she start eating it???

  3. The early confusion has been answered by more recent studies. The current science supports the use of soy in the diet of patients who have had breast cancer. Other videos you might find of interest is the effects of exercise on breast cancer: http://nutritionfacts.org/videos/exercise-breast-cancer/ and specific vegetables on breast cancer: http://nutritionfacts.org/videos/veggies-vs-cancer/ & http://nutritionfacts.org/videos/vegetables-versus-breast-cancer/. Animal and epidemiology studies support avoiding the consumption of animal protein in patients with cancer.

    1. I wrote a post about soy Should I stay away from soy if I have breast cancer? Although I do not touch on endometrial cancer tamoxifen is often prescribed. Ask your doctor when the best time to take your medication is if eating soy foods. There is no data to suggest whole soy foods cannot be consumed if you have endometrial cancer or you take tamoxifen. A great link by oncology RDs can be found here. Hope this helps!

  4. A friend was diagnosed with breast cancer recently and is undergoing conventional treatment, however with my advice is also trying her best to eliminate all animal products and believes that nutrition has an impact. Based on her current status and treatment schedule, please advise if there is anything else she should do.

    She has HER2 type breast cancer. She had a 10 cm tumour and cancer was present in the lymph nodes. She has had 3 rounds of chemo, and has 3 more to go. The first 3 were FEC and the remaining 3 will be DH, and she will remain on H for one year. In January she will have a radical mastectomy of the affected breast (despite the fact that as of now her tumour has shrunk to 4 cm) and the lymph nodes will be removed as well. She will have daily radiation for 4-6 weeks starting one month after surgery.

    Many thanks!!

    1. Thanks for reaching out. Your friend is lucky to have your support. While a plant based diet approach is certainly healthy, a couple of thoughts came to mind that you might want to check in with her about. First, how is her appetite and weight? A combination of diet change (especially if protein from animal sources have been eliminated and uptake of vegetarian sources isn’t quite there yet) and managing treatment related side effects can sometimes make it challenging for a person to get all the nutrients needed for health and healing. I would also be sure to encourage consumption of cancer fighting foods, herbs and spices and avoid supplements. For example, turmeric, a well known cancer fighting nutrient in culinary amounts is safe but steer clear of supplements. This is especially true during cancer treatment as we don’t want to inadvertently repair cancer cells! And of course always discuss with your oncologist. I hope this helps.

  5. Hi Dr Greger and team,

    I know this isn’t strictly a nutrition question, but my mother had early stage breast cancer, had it removed, chemo and radio therapies completed and just finished 5 years of Tamoxifen. The oncologist said that if she’s tolerating the drug, that there is a 2.8% increase in survival for continuing the medicine for an additional 5 years. It seems like an insignificant benefit for the seemingly high risk of Tamoxifen, given the huge list of potential side effects. Are you able to make a recommendation, or put it in perspective of Tamoxifen vs a Plant Based diet, which she has largely adopted?

    Thank you so much.

    B

  6. Boris,

    Hard question to answer as without all the data and the complexity of breast cancer it’s not a clear cut tamoxifen vs PB diet. There is indeed a diminishing effect and significant adverse events possible with tamoxifen.

    I am a firm believer in getting some integrated cancer advice and would suggest you contact the Cancer Centers of America and ask for a consult, after sending them your records. They utilize a more comprehensive view of treatment including diet and supplementation along with conventional drugs.

    Dr. Alan Kadish moderator for Dr. Greger

  7. I saw this video where Dr John McDougall is talking about the dangers of consuming isolated soy products, which increases IGF-1 levels, thus increasing your risk of cancer. It’s based on old research, but what if it’s still relevant (I’m really confused…What should we do…Should we eat soy products or not)?
    https://youtu.be/Na5R0bdNjZs

  8. I saw this video where Dr John McDougall is talking about the dangers of consuming isolated soy products, which increases IGF-1 levels, thus increasing your risk of cancer. It’s based on old research, but what if it’s still relevant (I’m confused…What should we do…Should we eat soy products or not)?
    https://youtu.be/Na5R0bdNjZs

      1. Hi Steven,

        I’ve watched all the soy videos already. It didn’t seem to answer my question. The other YT video that I linked in my comment, seemed to suggest that soy was dangerous (even more than dairy) because it promotes cancer growth (Even in small amounts). So I was just wondering if you know about the research Dr John McDougall (in the YT video link in my comment) was referring to, and if it’s still valid. Therefore, does it mean that your YT videos (with Dr Greger) are actually incorrect or not? I’m not sure which side to believe.

  9. The suggestion that soy is generally good for breast cancer is contradicted by the following article which states that soy isoflavones are bi-phasic: They promote BC at low concentrations and inhibit it at high concentrations (see Figure 1).

    https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5037722/

    Does anyone know the relationship between the consumption of regular soy, or of an extract, and the resulting serum concentration? No? So, how does one know the “safe” amount?

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