Soy And Breast Cancer Recurrence

Written by Dr. Steve Chaney on . Posted in Food and Health, Issues

The Truth About Soy And Breast Cancer

 Author: Dr. Stephen Chaney

SoybeanYou’ve probably heard the warnings: “Soy may increase the risk of breast cancer!” “Women with breast cancer shouldn’t use soy!”

The first warning was never true. Numerous clinical studies have shown that consumption of soy protein is associated with a lower risk of developing breast cancer.

Furthermore, the science behind the second warning has never been very strong. The concerns that soy might stimulate the growth of breast cancer cells was based primarily on cell culture experiments and one experiment in mice – even though a second experiment in mice came to the exact opposite conclusion.

Was The Hypothesis That Soy Could Increase The Risk Of Breast Cancer Recurrence Plausible?

The possibility that soy isoflavones could stimulate the growth of estrogen- responsive breast cancer was biochemically plausible because soy isoflavones bind to the estrogen receptor and have a very weak stimulatory effect (much weaker than estrogen itself).

Even that evidence was not definitive because soy isoflavones also turn on several tumor suppressor pathways in breast cells and help strengthen the immune system – so they could just as easily inhibit the growth of breast cancer cells.

However, because the concerns were plausible and had not been definitively disproved, most experts, including me, recommended for several years that women with estrogen- responsive breast cancer might want to avoid soy protein.

Has The Hypothesis Been Rigorously Tested?

In fact, the definitive clinical studies have been performed, and it turns out for women who are breast cancer survivors, consumption of soy foods does not increase either the risk of breast cancer recurrence or of dying from breast cancer.

The first of these studies was reported in the December 2009 issue of the Journal of the American Medical Association by researchers at Vanderbilt University and Shanghai Institute of Preventive Medicine (Shu et al, JAMA, 302: 2437-2443, 2009).

It was a large, well designed, study that enrolled 5042 Chinese women aged 20 to 75 years old who had been diagnosed with breast cancer and followed them for an average period of 3.9 years.

The women were divided into four groups based on the soy content of their diet (ranging from 5 grams/day to 15 grams/day). The results were clear cut. Breast cancer survivors with the highest soy intake had 25% less chance of breast cancer recurrence and 25% less chance of dying from breast cancer than the women with the lowest soy intake.

The effect was equally strong for women with estrogen receptor-positive and estrogen receptor negative cancers, for early stage and late stage breast cancer and for pre- and post-menopausal women. In short this was a very robust study.

The study also showed that soy protein intake did not interfere with tamoxifen, a drug that blocks the binding of estrogen to its receptor on cancer cells. Tamoxifen is used for both for treating estrogen-responsive breast cancer and preventing its recurrence. In this study, the reduction in the risk of breast cancer recurrence & death was just as great whether the breast cancer survivors were taking tamoxifen or not.

In fact, tamoxifen was protective only for women with low soy intake. It conferred no extra protection for the women at the highest level of soy intake because the soy isoflavones were also blocking the binding of estrogen to its receptor.

Other Clinical Studies

If that were the only published clinical study to test the soy-breast cancer hypothesis, I and other experts would be very cautious about making definitive statements. However, at least four more clinical studies have been published since then, both in Chinese and American populations. The studies have either shown no significant effect of soy on breast cancer recurrence or a protective effect. None of them have shown any detrimental effects of soy consumption by breast cancer survivors.

A meta-analysis of all 5 studies was published earlier this year (Chi et al, Asian Pac J Cancer Prev., 14: 2407-2412, 2013). This study combined the data from 11,206 breast cancer survivors in the US and China. Those with the highest soy consumption had a 23% decrease in recurrence and a 15% decrease in mortality from breast cancer.

The Bottom Line:

What does this mean for you if you are a breast cancer survivor?

1)     There are many reasons to include soy protein foods as part of a healthy diet. Soy foods are one of the highest quality vegetable protein sources and provide a great alternative to many of the high fat, high cholesterol animal proteins in the American diet.

2)     I personally feel that these studies are clear cut enough that breast cancer survivors no longer need to fear soy protein as part of a healthy diet.

3)     The responsible websites agree with this assessment. For example, WebMD and the American Institute for Cancer Research (AICR) both say that breast cancer survivors need no longer worry about eating moderate amounts of soy foods.

4)     The irresponsible websites (I won’t name names, but you know who they are) are still warning breast cancer survivors to avoid soy completely. As a scientist I really have problem with people who are unwilling to change their opinions in the face of overwhelming scientific evidence to the contrary.

5)     Of course, some of those bloggers have now shifted their arguments to say that it is unfermented or genetically modified soy that causes breast cancer. Those statements are equally bogus – but that’s another story for another time.

6)     Finally, I want to emphasize that the published studies merely show that soy does not increase the risk of breast cancer and is safe to use for breast cancer survivors. None of those studies suggest that soy is an effective treatment for breast cancer. The protective effects of soy are modest at best. If you have breast cancer, consult with your physician about the best treatment options for you.

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.

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Comments (6)

  • Pam

    |

    Dr. Chaney — THANK YOU for the clarification!! I found this article easy to understand!

    Reply

  • Marie

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    This is fantastic information! I am wondering how estrogen plays a role in soy consumption for the average person. Many doctors claim that pumping estrogen (by means of soy consumption) into men or nursing babies through their mother’s milk is dangerous and can be harmful, possibly sterilizing, men. Do these claims hold any truth?

    Reply

    • sysadmin_htftp

      |

      Dear Stella,
      That information is also misleading. Look for an article in a few weeks summarizing the latest clinical studies on the effects of soy consumption on men.
      Dr. Chaney

      Reply

  • Susan

    |

    I am so glad to see this article and the timing is perfect for me. I have discussed with my Medical Oncologist, my soy protein shakes. I am in chemotherapy , my hormonal status is estrogen positive and she advised, she would prefer I did not have any soy products.

    I am going to take a copy of your email to my chemo appointment next Tuesday and see if she will change her mind.

    Thank you so much for this wonderful information.

    Reply

    • sysadmin_htftp

      |

      Dear Susan,
      You are doing exactly the right thing by discussing this information with your doctor. I can only report on the results of published clinical studies that represent the average effects of soy on breast cancer recurrence in a large group of breast cancer survivors. However, you are unique. What applies to the group as a whole, may not apply to you as an individual. That is why your oncologist is the best person to evaluate the data and give you the advice that best applies to you as an individual.
      Dr. Chaney

      Reply

  • Teresa Robinson

    |

    Thanks, Dr. Chaney. Several in my family and several friends have had breast cancer. The topic is one that is always top of mind.

    Reply

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Latest Article

How to Choose the Right Pillow

Posted April 17, 2018 by Dr. Steve Chaney

Wake Up Each Morning Pain Free

Author: Julie Donnelly, LMT – The Pain Relief Expert

Editor: Dr. Steve Chaney

 

how to choose the right pillow without headachesThe way you sleep is often a key to discovering the cause of headaches and more. If you wake up with neck pain, a headache, or you suffer from ringing in your ears, dizziness, or ear pain, there is a good possibility that it may be caused by the way you are sleeping. Your pillow may be the culprit.  But if you need to know how to choose the right pillow for you, it’s easy.   It just takes a little “investigation.”

 

How to Choose the Right Pillow if You Sleep On Your Side

Your head, neck, and spine need to always stay in a nice straight line, just as it is when you are standing up, but that takes a little thought and understanding of the way you sleep.  So, get comfy in your bed and then notice how your head is resting.

how to choose the right pillow to sleep painfreeIf you sleep on your side, your pillow needs to be just the right size, so your head doesn’t point down toward the mattress (your pillow is too soft) or up to the ceiling (your pillow is too thick). Either of these positions will make the muscles on the side of your neck stay in the contracted position for hours and pull your vertebrae in that direction, especially when you try to turn over to your other side.

Your SCM Muscle May Cause Serious Problems

You also need to notice if you turn your head a bit, especially if you are turning into your pillow or turning your head up toward away from your pillow. In either of these two cases you will be causing your sternocleidomastoid (SCM for short) to be held shortened for hours.

Your SCM originates on your collarbone and inserts into the bone behind your ear.  When it contracts you turn your head to the opposite side. However, if the muscle is tight (for example, when you’ve held your head turned toward one side for an extended period of time) and then you bring your head back so you are facing forward, the tight muscle will pull on the bone behind your ear and cause havoc.

The symptoms for a tight SCM are tinnitus (ringing in the ear), dizziness, loss of equilibrium, ear pain, headaches, pain in the eye and around the skull, pain at the top of the head, and even pain in the throat. Amazing! What’s even more amazing is that it’s rare that this muscle is considered when a medical professional is searching for the cause of your symptoms.

These are the things to know when considering how to choose the right pillow if you sleep on your side.

How To Choose The Right Pillow If You Sleep On Your Back

how to choose the right pillow for sleeping on your backIf you sleep on your back, your head should be on the mattress (not propped up with a pillow) and you should have a tiny support (like a folded washcloth) under your neck.  Or, you can have a wedge pillow that starts at your mid-back and gently raises your entire trunk and head up while still allowing your head and back to be in a straight line.

It’s always a challenge for people who toss and turn during the night, sometimes on their side and sometimes on their back.  The best thing I’ve found for this situation is to have the pillow below shoulder level so when you turn on your side your shoulder will automatically slide to the edge of the pillow while still supporting your head properly, and when you turn onto your back, the pillow will start at shoulder level so your head and neck are supported, but your head is being pushed in a way that causes your chin to move down to your chest.

hip pain causes and treatment pain freeIt’s tricky, but I can personally attest to the fact that it will work.  I can always tell when I’ve had my head tilted (I toss and turn during the night) because I will wake with a headache. When that happens I’m grateful that I know how to self-treat the muscles of my neck and shoulders so the headache is eliminated quickly.  If you already have Treat Yourself to Pain Free Living,  you can self-treat all your neck and shoulder muscles to release the tension.

How To Choose The Right Pillow If You Sleep On Your Stomach

If you sleep on your stomach, this is the one position that is so bad that it behooves you to force yourself to change your position. Your head is turned to the side and held still for hours, putting a severe strain on all your cervical and upper thoracic vertebrae. Not only will this cause headaches, tinnitus, and a list of other pains, but it can cause problems down your entire spine. It can also impinge on the nerves that pass through the vertebrae on their way to your organs.

If you do sleep that way, let me know and I’ll give you some suggestions that work to change your habit of sleeping. It takes time and energy, but the results are worth the effort.

In every case, the way you sleep may cause neck pain that won’t go away until the pillow situation is resolved.

Now you should know how to choose the right pillow for the way you sleep.

Wishing you well,

Julie Donnelly

About The Author

julie donnelly

Julie Donnelly is a Deep Muscle Massage Therapist with 20 years of experience specializing in the treatment of chronic joint pain and sports injuries. She has worked extensively with elite athletes and patients who have been unsuccessful at finding relief through the more conventional therapies.

She has been widely published, both on – and off – line, in magazines, newsletters, and newspapers around the country. She is also often chosen to speak at national conventions, medical schools, and health facilities nationwide.

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.

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