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All TopicsForum: Complementary and Holistic Medicine and Treatment → Topic: Scientists Untangle the Soy-Breast Cancer Paradox

Topic: Scientists Untangle the Soy-Breast Cancer Paradox

Forum: Complementary and Holistic Medicine and Treatment — Complementary medicine refers to treatments that are used WITH standard treatment. Holistic medicine is a term used to describe therapies that attempt to treat the patient as a whole person.

Posted on: Feb 2, 2017 08:00AM

cp418 wrote:


Scientists Untangle the Soy-Breast Cancer Paradox

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Feb 2, 2017 05:12PM - edited Mar 21, 2018 02:47PM by 123JustMe

This Post was deleted by 123JustMe.
Oncotype 15 Dx 6/2015, IDC, Left, <1cm, Stage IA, Grade 1, 0/3 nodes, ER+/PR+, HER2- (FISH) Surgery 7/23/2015 Lumpectomy: Left; Lymph node removal: Sentinel
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Feb 4, 2017 07:45AM claireinaz wrote:

Thank you for posting. For years I've been wondering about this and this makes things a bit easier to understand, if indeed the animal studies can be translated to humans.

The way I'm reading it is if you ate soy for years and then had a b.c. dx, it's okay to eat some soy afterward. Since I was vegan and then vegetarian for years, and ate tofu and some soy meatless products from time to time, I'm discerning that eating soy from time to time now probably won't hurt me, if the studies are to be trusted and can be translated to human consumption.

Yes? No?

9/29/11 ILC, 2 c. stage II grade 1, ER/PR+ HER2-, 6/11 nodes, lumpectomy, DDAC x 4, Taxol x 12, 33 rads, Tamoxifen/arimidex/aromasin, BMX/immed recon 7/3/13 "In the midst of winter, I found in me an invincible summer.” Albert Camus
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Feb 4, 2017 10:37AM - edited Mar 21, 2018 02:47PM by 123JustMe

This Post was deleted by 123JustMe.
Oncotype 15 Dx 6/2015, IDC, Left, <1cm, Stage IA, Grade 1, 0/3 nodes, ER+/PR+, HER2- (FISH) Surgery 7/23/2015 Lumpectomy: Left; Lymph node removal: Sentinel
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Feb 4, 2017 11:44AM Beesie wrote:

I'm glad to see this study, even if at this point it is just based on rats. What this study does is pull together and support the findings from a number of earlier studies.

  • Quite a few previous studies, mostly done among Asian populations, that have found that women who consume significant amounts of soy starting in childhood or adolescence tend to have lower breast cancer rates as adults.


  • There have also been a number of studies, mostly lab and/or mouse/rat but some based on humans in Western countries (i.e. women who have Western and not Asian diets), that have shown that soy consumption after an ER+ breast cancer diagnosis increases recurrence risk. It was these types of studies that led many of us, myself included, to be told that we should minimize our soy consumption after we'd been diagnosed.


For years people thought that the results from these two different types of studies was inconsistent, and there has been a lot of discussion (including on this site) to suggest that the first group of studies (which show a benefit to soy) negate the second group of studies (which show possible harm to those who have been diagnosed with an ER+ breast cancer). I never saw an inconsistency in the results. Here are a couple of old posts of mine, the first from June 2007 and the second from January 2009:

"There has been one study (and maybe more) that suggests that if teenage girls and young women eat soy, it may reduce their future risk of breast cancer. This is far from being proven, but the soy industry, and the health food industry who are so gung-ho on soy, have taken this to mean that "soy reduces breast cancer". But an adolescent consuming soy is a totally different situation than a women who's had estrogen-driven breast cancer consuming soy. Although these studies aren't 100% conclusive either, the indication is that soy, being a phytoestrogen, is harmful to women who've had breast cancer."

"I think one of the problems we have to consider is that the dietary rules may be different if you are trying to prevent breast cancer vs. if you've had it. From my understanding, studies have shown that soy can be effective at reducing the occurrence of breast cancer and as a result, it's advised that young girls start consuming soy and continue through adulthood. Similarly, women in Asian countries who consume soy starting in childhood have lower breast cancer rates. But, if soy has not been part of your diet since childhood and/or if you have an ER+ breast cancer, soy may be problematic in the way in which it adds estrogen into your system and how that estrogen acts. It appears that how soy reacts in our systems may be different if it's a lifelong habit vs. if it's a new or infrequent habit. And it may be different if we are pre-menopausal vs. if we are postmenopausal."

Nice to see a study that confirms what I've been saying for all these years! Nerdy

Now we need more information to understand what level of previous soy consumption, and starting at what point in life, makes a difference to one's post-diagnosis risk. I never consumed soy as a child or adolescent, but I consumed a lot of soy in the 10 years before I was diagnosed. Did I consume enough soy, and early enough, that soy would have been beneficial to me after my ER+ diagnosis? Or did I start too late and would a continuation of my soy consumption have increased my recurrence risk? And what about those 10 years of soy consumption, started well into adulthood? Harmful, possibly fueling my BC development, or helpful, possibly reducing my BC risk? The problem with the nuanced findings from this study is that it just leads to more questions!

Dx 9/15/05, DCIS-MI, 6cm+ Gr3 DCIS w/IDC microinvasion, Stage IA, 0/3 nodes, ER+/PR- “No power so effectually robs the mind of all its powers of acting and reasoning as fear.” Edmund Burke
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Feb 4, 2017 12:43PM - edited Feb 4, 2017 12:52PM by BarredOwl

Here is the original Georgetown Press Release that the above feature is based upon:


Here is a link to the abstract of the underlying publication (full-text article behind a paywall):

Zhang (2017): "Lifetime Genistein Intake Increases the Response of Mammary Tumors to Tamoxifen in Rats"

Abstract: http://clincancerres.aacrjournals.org/content/23/3/814

If I am reading it correctly, it seems like all of the rats received tamoxifen. Describing the purpose and experimental design of the study, they state (in part):

"We compared the effects of genistein intake mimicking either Asian (lifetime) or Caucasian (adulthood) intake patterns to that of starting its intake during tamoxifen therapy using a preclinical [rat] model."

"When the first tumor in a rat reached 1.4 cm in diameter, tamoxifen was added to the diet and a subset of previously only control diet–fed rats also started genistein intake (post-diagnosis genistein)."

They found (in part) and concluded (in part):

"Lifetime genistein intake [in rats] reduced de novo resistance to tamoxifen, compared with post-diagnosis genistein groups. Risk of recurrence was lower both in the lifetime and in the adult genistein groups than in the post-diagnosis genistein group."

"[In rats,] Genistein intake mimicking Asian consumption patterns improved response of mammary tumors to tamoxifen therapy, and this effect was linked to reduced activity of UPR and prosurvival autophagy signaling and increased antitumor immunity."

I wonder if similar differences in recurrence risk would be observed between "lifetime" and "adult" groups versus the "post-diagnosis" group either in the absence of tamoxifen or in rats receiving an endocrine therapy drug having a different mechanism of action (e.g., an aromatase inhibitor).


Stage IA IDC, 9/2013 BMX. Right: IDC (1.5 mm, grade 2) with DCIS (5+ cm), 0/4 nodes, pN0. Left: DCIS (5+ cm), 0/1 node, pN0(i+).
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Feb 4, 2017 05:17PM wallycat wrote:

This was also my concern, since Asians start soy/tofu from birth---I added it as a young adult. I wonder if that was more hurt than help and maybe contributed to my breast cancer? Or did it make it less aggressive ? or who knows. And I do wonder how valuable a rat study is when extrapolated to humans.

Dx 4/07 1 month before turning 50; ILC 1.8cm, ER+/PR+, HER2 neg., Stage 1, Grade 2, 0/5 nodes. Onco score 20, Bilateral Mast., tamoxifen 3-1/2 years, arimidex-completed 4/20/2012
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Feb 4, 2017 11:05PM ChiSandy wrote:

I was also told by our cancer center’s survivorship-program doctor that soy grown in Asia (as well as the products made from it) is different from the soy grown by agribusiness.

Diagnosed at 64 on routine annual mammo, no lump. OncotypeDX 16. I cried because I had no shoes...but then again, I won’t get blisters.... Dx 9/9/2015, IDC, Right, 1cm, Stage IA, Grade 2, 0/4 nodes, ER+/PR+, HER2- Surgery 9/22/2015 Lumpectomy: Right Radiation Therapy 11/1/2015 3DCRT: Breast Hormonal Therapy 12/30/2015 Femara (letrozole)
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Feb 22, 2017 08:23PM - edited Feb 22, 2017 08:25PM by gardengypsy

I wouldn't buy soy from either Asia or our big ag.http://www.vermontsoy.com/

Dx 10/29/2015, ILC/IDC, Left, 5cm, Stage IIIA, Grade 3, 1/1 nodes, ER+/PR+, HER2- Surgery 12/3/2015 Lymph node removal: Sentinel; Mastectomy; Reconstruction (left): Tissue expander placement Chemotherapy 1/9/2016 AC + T (Taxol) Surgery 5/23/2016 Hormonal Therapy 5/28/2016 Tamoxifen pills (Nolvadex, Apo-Tamox, Tamofen, Tamone) Radiation Therapy 6/6/2016 Whole-breast: Breast, Lymph nodes, Chest wall

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