Your Thyroid Problem and Your Breast Cancer Risk

A 36 year-old spunky, bold, compassionate mother of two (and good friend of mine) discovered her own breast cancer. It wasn’t even a lump, more of a “leatheriness,” she said, and she almost hated to go get it checked out, as it felt like something she might just be imagining. But alas, it was not an overactive imagination. It was advanced breast cancer requiring chemotherapy, radiation, and mastectomy.

When I was in med school, I was taught that breast cancer under the age of 40 was RARE. Yet, every month or so it seems as if I hear a story of someone younger than 40 getting breast cancer. Good friends and acquaintances. Indeed, the statistics are changing, and it is a documented, terrifying fact that breast cancer rates are increasing in women younger than 40 years old, particularly the rates of advanced breast cancer requiring chemotherapy and radiation. (1)

(This post will not be about  breast cancer. It’s just going to briefly touch on the idea that thyroid condition patients are at higher risk for breast cancer, a fact I don’t think they all know.)

“Could my thyroid cancer have anything to do with my breast cancer?”

My friend asked her breast surgeon: “Could the thyroid cancer I had when I was younger have anything to do with my breast cancer?”

His reply to her question was apparently a flat-out NO.

He told her wrong.

If you read no further than this next paragraph, here’s my take-home:

If you have thyroid disease, I encourage you to be assertive about breast monitoring. Those with thyroid disease deserve to know that certain thyroid conditions are definitely associated with an increased risk of breast cancer.  Print off any of the articles I list in my references which may apply to you and take them into your healthcare provider to develop a breast monitoring plan together.

Thyroid Cancer Points to a Woman at Higher Risk for Breast Cancer

Thyroid cancer is associated with an increased breast cancer risk. In 2015, Dr. Jennifer Kuo (M.D.) of Columbia University presented pooled data from something called the Surveillance, Epidemiology, and End Results Database-9 (between the years of 1973-2011), reporting that patients who had had thyroid cancer were at an increased risk for developing breast cancer in comparison to the general population.

The 10-year risk for developing breast cancer at 40 years old was 5.6% after having thyroid cancer, while for the general population, breast cancer risk was only 1.5%. By age 50, the rate increased to 12.8% while the general population hung out at about 2.4%.

Simple recap for those with a history of thyroid cancer:

  • At age 40, 5.6% risk of breast cancer versus 1.5% risk in “normal people.”
  • At age 50, 12.8% risk of breast cancer versus 2.4% in “normal people.” (2)

Review of different data by other researchers indicated that a woman who had survived thyroid cancer was 1.18 times more likely to develop breast cancer than controls. Interestingly, this review also indicated the risk went the other way too! A breast cancer patient was 1.55 times more likely to develop thyroid cancer than the general population. (3)

So the answer is not NO. The answer is YES.

If you’ve had thyroid cancer, you and your doctor need to know that you’re at a higher risk for breast cancer and should take steps for monitoring your breast tissue.

Will Continue Next Post

In the next post, I’ll briefly cover other thyroid conditions and what the research indicates regarding breast cancer risk. And of course link it to food and encourage you to stick with whole, real food rich in vegetables and fruits! Both you AND your kids.

Have a wonderful Monday! Remember something that really makes you smile today. Think on it all day. And let that smile out. Share it. The world changes only as people’s hearts change. Your smile and joy can change people’s hearts.




(Doing the citations is the biggest headache of my scientifically related posts, but I think citations are monumental to include–and especially helpful when the citation is linked to the piece of information in the article so you don’t have to go searching for which article information came from. When I re-write paragraphs, it messes the citation order ALL up. What a headache. So please, let me know if something doesn’t look right and I need to look at it again. Or if you’re a scientific writer who knows the trick to doing citations more easily, please do share!)

1. Johnson RH,  Chien FL, Bleyer A. Incidence of Breast Cancer With Distant Involvement Among Women in the United States, 1976 to 2009. JAMA. 2013;309(8):800-805; doi:10.1001/jama.2013.776.

2. Thyroid-Cancer Survivors at Higher Risk of Breast Cancer. Medscape Web Site. Published June 1, 2015.

3. Nielson SM et al. The Breast-Thyroid Connection Link: A Systemic Review and Meta-Analysis. Cancer Epidemiol Biomarkers Prev. February 2016 25; 231. doi: 10.1158/1055-9965.EPI-15-0833.

4 thoughts on “Your Thyroid Problem and Your Breast Cancer Risk

  1. Rachel J

    Thank for writing this Terri! Although I still don’t have a definitive answer from my doctors about the connection, I just know there has to be one. I have since made 2 different friends, both breast cancer survivors, both HER2+, ER/PR – like me, who have developed masses in the thyroid. The connection just has to be there. That being said, I have really learned a lot about the body and myself during this journey and there are several things I always emphasize to women now. The first is don’t assume it is not cancer. Know your body, know your breasts and know when something is different and always have it checked out. I literally had no risk factors. None. Not even family history. Didn’t really have a “lump” per se. Difference in skin and felt thicker. If I hadn’t been paying attention, with the type I had, I would have very quickly progressed to Stage 4 as I was 5 years away (10 if the standards actually change!!!) from a mammogram. Also, especially if you are young with dense breast tissue, always request an ultrasound too. The mammogram did not show the invasive tumor, but my doctor had been proactive and automatically scheduled an ultrasound with it. Without that, this would be a whole different story. I would also say I am confident that nutrition plays a big part in cancer growth, development amd mestateses although the jury seems to be out on how. Research and articles conflict, oncologists and dietitians often disagree on what helps and what doesn’t. However, they all agree that plant based diets and whole foods have a positive impact. I also firmly believe that because I was young and healthy, it was much easier for my body to fight and to handle the chemo, radiation and surgeries. I ate pretty healthy (better than the average American) before this so I am still not sure what it is in my body that causes cancer to grow (It obviously has something to do with triggering the HER2 protein) and Dr Moses (whom I adore as you know!!) says I ask the million dollar question every time I ask that! But I do know that as a cancer patient, and really ANYONE, my best bet is to eat a whole, healthy diet and exercise and give my body the best chance and opportunity to do what God created it to do and to be able to curb anymore growth and recurrence and to be strong enough to fight and handle treatment if it does return. I am 17 months out of chemo, 1 year out of radiation and 8 months out of Herceptin and I finally am starting to regain energy and feel normal. I am 11 days into Whole 30 and feel great! My goal is to use this to jumpstart my eating, examine my nutrition and prepare my body to be healthy and fight! Love and miss you very much! -Rachel

    1. thehomeschoolingdoctor Post author

      Dear Rachel,

      To me, you’re the advocate for “Know thyself and advocate for thyself (and others).” Love you and miss you too!

      Thank you so much for commenting! I’m sorry for the delay. I was “home” for a long visit and then had to visit a sick aunt in Germany. So I’m trying to catch up. Interesting your two friends went on to have nodules in their thyroids. I don’t think one causes the other. I think (when I have time to 🙂 ) that whatever is going on in the body allows both to happen. I totally agree with a whole, real, fresh plant-based diet for cancer. (Not excluding meat, but focusing lots on the fresh, real, whole.) I also think that making sure patients get omega-3s and iodine might be important. As in, eat your seafood.

      You’ve got a about a week left of Whole30! How’s it going? I really like the Whole30 program. Good luck! I think it helps us see exactly how many times we eat food that has been processed. Just makes us more aware so we can’t fib so easily to ourselves that we’re eating real food or not eating that much “sugar.”

      And I’m glad your energy is coming back. And I’m glad you are cancer-free. And I’m glad you are you and that I know you. And that Dr. Moses respects you and honored that hunch you had. And that God, our maker, love, and life, wraps us all in His arms as we reach out to Him, and He’ll hold us for eternity, even when the life on earth seems so daunting or useless or painful.

      Ah, the baby just woke up! Time’s up. Thanks for sharing your story and experience and thoughts as an insider.


      1. Anonymous

        Terri I have one day left on Whole 30 and I have loved it! I gained about 25 lbs during treatment (which they say is normal) and I just couldn’t get it off. I just needed something to jump start it. I liked that it was only 30 days and that even though you eliminate a lot, you don’t have to count anything. If it is good, it is good. You can eat it. I don’t have time to track and count everything I put in my mouth! And honestly, as I am approaching the end, I really don’t think I will stop. I will reintroduce alcohol (I miss a glass of wine! ) and we all know it is inflammatory but I don’t drink enough for it to matter to me. I will also reintroduce legumes and corn to see how they do. The other stuff, I just don’t miss. I feel better, I know I have lost weight, my body doesn’t feel as “old” and I really just have no desire to eat the junk anymore. It is not appealing. And I do agree about examining what we eat. It really, really makes you aware of how processed our food is and how sugar is in EVERYTHING! It also teaches you that food really is just fuel.

        You are so right about God holding us. When you reach a point where you are truly faced with this life ending you realize what a comfort our secure eternity in Him is. How He is all we can really find security and peace in. Everyone of us will face it one day, some of us just sooner than others. I try to think of what I went through as a gift. It has made me worry much less, be less stressed in general and learn how to focus on what is important. It was a reminder that even in death, God has provided for us and there is nothing else to fear!

      2. thehomeschoolingdoctor Post author

        I’m way late replying. I can’t seem to get to the computer! I like what you say about eating that way makes you feel “not so old.” I noticed that too! I felt as good as I did my senior year of high school!

        Your last paragraph says it all. That’s the door.

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