Certain common thyroid conditions put women at a higher risk for breast cancer, yet this isn’t common knowledge to even medical professionals.
Why Isn’t It Common Knowledge That Certain Thyroid Diseases Are Associated with Higher Breast Cancer Risk?
The research available on a thyroid disease and breast cancer connection is very, very conflicting, depending on the thyroid disease state and the study being looked at. One study says there are Martians, and other studies say there are not. (Joke.)
How can medical research be so murky? It is frustrating, but I think there are some reasons for it:
One. There is not a direct causal effect between thyroid disease and breast cancer. Having thyroid disease does not cause breast cancer. It’s just that there’s something medical researchers and clinicians haven’t pinpointed with unanimous certainty leading to faulty issues in both organs. Flooding in the basement doesn’t cause my leaky roof; the rain does. (Yes, iodine advocates, I agree. It could be in part a deficit of iodine and its associated necessary co-factors.)
Two. Another problem leading to “research conclusion confusion” in this matter, I believe, is how thyroid disease is diagnosed. About everyone can agree on a TSH (an initial screening thyroid function test), but after that, it starts becoming no-man’s-land about what should be ordered next.
In general, there is an over reliance on TSH, and less monitoring of other thyroid tests, especially thyroid antibodies. Sometimes patients are simply given the diagnosis of “Your-TSH-is-too-high-here-take-this-Synthroid” and little else, if anything, is checked–sometimes not even the thyroid gland itself! I was floored when a newly suspected thyroid patient (a friend) told me the doctor didn’t even feel her thyroid! Another friend, who I sent to go see her doctor for a new goiter (and symptoms of hypothyroidism), was given a good bill of health with no recommendation for close follow-up or any inquiry into her diet; her TSH was normal and so was her ultrasound.
So in the studies, I have to wonder what it means when they say Hashimoto’s, hypothyroidism, or hyperthyroidism. How uniform are the patients in reality? How were all the patients diagnosed? Because so much data was pooled from so many studies for some of the bigger research analysis, it’s hard to say.
Three. Different doctors use different terminology. For example, Hashimoto’s disease can be called 1) Hashimoto’s 2) hypothyroidism or 3) chronic autoimmune thyroiditis (or chronic thyroiditis, autoimmune thyroiditis). Hashimoto’s IS a type of hypothyroidism, but not all hypothyroidism IS Hashimoto’s. However, some doctors will diagnose someone with Hashimoto’s without ordering antibody tests or even imaging. I think some studies aren’t able to tease out how different doctors label thyroid disease differently.
Four. Thyroid fluctuation can also confound statistics. A diseased thyroid will often fluctuate in its function for years, sometimes overproducing thyroid hormone, other times under producing thyroid hormone, and other times managing to make just the right amount of thyroid hormone. Eventually, after years, it may arrive at its final diseased balance. If a patient is monitored at one particular time, they may look completely normal based on TSH. The natural progression of thyroid disease is one of relapsing and remitting changes, sometimes high, sometimes low, and sometimes normal, and I believe this will affect research findings.
Okay. So now that you see reasons why the studies may be so contradictory, let’s look at different thyroid disease states and their breast cancer risk.
The following information may not make sense to you unless you have thyroid disease. Sometimes, even people who have thyroid disease don’t know their specific diagnosis, and this might sound complex even to them. I encourage you, if you have thyroid disease, to know specifically what you’ve been diagnosed with and how that diagnosis was arrived at (TSH, T3/T4 values, imaging, antibody tests, etc.).
Graves’ disease patients seem to consistently show up with higher breast cancer rates. (1, 2, 3)
Hyperthyroidism, not necessarily classified as Graves’ disease, has been shown to have a higher risk of breast cancer. (4)
A patient who has TSHR antibodies (usually diagnostic for Graves’ disease) has an increased risk for breast cancer. (2)
TPO antibodies and thyroglobulin antibodies, commonly found in autoimmune thyroid disorders (Hashimoto’s and Graves’ disease), have been found in some studies to be associated with a higher risk of breast cancer, but in other studies the antibodies were shown to have no relationship, or even an improvement, in the rate of breast cancer.
- TPO Antibodies:
- In some studies, TPO antibodies seem to be associated with less risk of breast cancer. (5)
- Other studies indicate a higher risk of breast cancer with TPO antibodies. (6, 7)
- Thyroglobulin antibodies:
- May suggest, but not statistically significant, an increased breast cancer risk. (2)
- Do show an increased risk for breast cancer. (6, 7)
Nodular goiter and diffuse, non-toxic goiter are associated with an increased risk of breast cancer incidence. (8, 9)
Hashimoto’s or hypothyroidism (Hashimoto’s usually causes hypothyroidism) patients can take their pick, as there have been reports with no significance in the rate of breast cancer (10), a decreased risk of breast cancer (4), or an increased risk of breast cancer (11).
Okay. I’m reaching my word and reader attention span limit, but I want to tell thyroid patients that this knowledge should not mean fear. Do not be afraid.
This knowledge means vigilance—lovingly tend to your body with good sleep habits, stress management, nurturing connections with friends and family, activity outside in the fresh air, and whole, real food choices rich in vegetables and fruits, and food sources rich in what both the breast and thyroid need.
This knowledge means to talk to your doctor about self-breast exams and mammograms. It means to learn the signs and symptoms of breast cancer, like skin changes and/or nipple discharge. Mammograms and self-exams should probably be more assertive than in a patient with no breast cancer risk factors, especially now as the mammogram guidelines suggest starting later and doing fewer mammograms (which I’m not adverse to that idea necessarily either, but not in patients at known higher risk).
I suggest you know the specific type of thyroid disease you have and whether or not you have antibodies. Doctors think it’s overkill to check antibodies, but if you take in a study that I’ve listed showing an increase in breast cancer with these antibodies, I think a reasonable doctor working with a reasonable patient would order them. I also think that knowing whether or not you’re consuming adequate iodine and iodine co-factors is important. Doctors aren’t well educated on iodine, other than, “Don’t,” and so finding someone who has read some of the newer stuff on iodine insufficiency, women, and breast disease is challenging.
No fear. No anxiety. Awareness. Uncontrolled anxiety does a woman no good. Sure, a little anxiety motivates us. But too much paralyzes us.
The last thyroid and breast post I did discussed thyroid cancer, so if you’re interested, go back and check that one out. Let me know typos, citation issues, or anything else pertinent to the accuracy of this post. Lastly, my blog is not professional advice. Use the citations I list to help you understand your disease better and to help you discuss your own case with your healthcare team better.
Strength and joy to you all!
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. http://jama.jamanetwork.com/article.aspx?articleid=165625
2. Thyroid-Cancer Survivors at Higher Risk of Breast Cancer. Medscape Web Site. http://www.medscape.com/viewarticle/845605. 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. http://cebp.aacrjournals.org/content/25/2/231.abstract
4. Sogaard M et al. Hypothyroidism and hyperthyroidism and breast cancer risk: a nationwide cohort study. Eur J Endocrinol. 2016 Apr;174(4):409-14. doi: 10.1530/EJE-15-0989. http://www.ncbi.nlm.nih.gov/pubmed/26863886
6. Turken O, Narin Y, Demirbas S, eta al. Breast Cancer in Association With Thyroid Disorders. Breast Cancer Res. 2003;5(5). https://breast-cancer-research.biomedcentral.com/articles/10.1186/bcr609
So what about the issue of mammograms and radiation? Studies I have read say that cancer is already pretty established when it can be viewed on a mammogram. What about other imaging without the negative effects of radiation? What can you do when your doctor says thyroid numbers look good but you have symptoms of thyroid issues that are blamed on menopause (hot flashes, hair loss) and just brush over your concerns.
Dear Terri, Okay. Let’s see.
“So what about the issue of mammograms and radiation?”
Yes. I hear you. I think the radiation dose is small. For some breasts it will not be an issue. For others, it will be. Case in point: Researchers found that when they looked at women known to be at high risk for breast cancer (with the genetics or family history) who had had mammograms early or repeatedly, these women had even higher rates of breast cancer. This seems to indicate those breasts are more sensitive to radiation (or squishing or fear or we don’t quite know what). Here is a link to read a summary of that.
I wish we could predict who is sensitive.
“Studies I have read say that cancer is already established when it can be viewed on a mammogram.”
Mammogram and ultra sound are both common breast cancer screening tools. They are not very sensitive to picking up cancer, which means they can miss it quite frequently. I’ve read numbers like 50/50. So definitely not the best. Breast MRI is better.
This is a different path to consider, but some people think that we over diagnose breast cancer (and other cancers). That some of these cancers will do no harm if watched. But, again, we don’t know who will have the aggressive cancer and who will not. Perhaps some breast cancer could be watched expectantly, and others not. This is definitely something to talk with a doctor about if breast cancer is diagnosed.
“What about other imaging without the negative effects of radiation?”
Yes. Breast MRI, in my mind right now, is the best option. No radiation, although very expensive. Getting insurance to pay would be tough, but there are certain criteria in which they will pay. It might be worth it for a person to look up those criteria and see if they qualify; I don’t know what they are. I’d look along the lines of increased breast cancer risk (there might be a percentage increased risk they need over baseline population, which would take some digging to see for each particular thyroid disease–if it meets that), dense breasts, or family history if you have some. I had a friend whose mom had breast cancer who decided to fork out the money for it despite the insurance not paying. This should just be considered on a case by case basis. We can’t go around throwing money we need for necessities.
Ultrasound is hit or miss, but less expensive and a commonly accepted screening test. And then breast thermography, which I’d not heard of much till this year as I read. I still don’t know what to think about it. It seems as good as mammogram and ultrasound, the newer thermography does. Maybe even better for women under 40 and/or dense breasts. It lacks specificity, which means many false positives—but so does ultrasound and mammogram. So, it could send women on a wild goose chase for a false positive, like mammo and U/S often do. Yet, no radiation, and when used as part of a screening plan may be useful. Not accepted well at all that I can see by conventional doctors. See here for a link to read about a study on it:
“What can you do when your doctor says thyroid numbers look good but you have symptoms of thyroid issues that are blamed on menopause (hot flashes, hair loss) and just brush over your concerns?”
I’d have a conversation like this (which you may have already had). “Look, Dr. XYZ, I just have not been feeling good. I know you’re really busy today, but please hear me out just a minute. I won’t take long. I know you think it’s me going through menopause, and maybe it is just that, but I feel bad. Please, can we just check these lab tests for my thyroid? I know in some thyroid diseases that thyroid antibodies correlate with symptoms, like in the eye disease of Graves’ disease (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3663223/), so maybe it’s true in other forms of thyroid disease too. Have we checked my antibodies? Please can we check those? (anti-TPO, anti-thyroglobulin, TSHR antibody) And can we maybe every 4-6 months for about 1-2 years check my free T3, free T4 and reverse T3, in addition to the TSH?” Then, I’d gauge response. Do you want more? How is it being received? If it’s not being received well, honestly, I’d consider if this person is the doctor for me. Because, at this point, I’d also want to bring up a supplement program that I’d want to try, but I’d like some monitoring on. But if the doctor can’t give you even this, I’m thinking a doctor who has more time, more energy, more awareness of his/her gaps of knowledge, more interest in treating you as a person rather than a guideline is called for.
Good questions, Terri. My biggest thing in life is to never give up, to find a way. To not let the slumps keep me there. It’s mostly all a spectrum of using clues and making adjustments along the way.
I was listening to a podcast this week and it was about the Medical field and how new it is. There is so much that we do not know and yet we expect doctors to know every disease, symptoms, and connections between them. It really opened my eyes about how we humans are just starting out learning about everything entailed in the medical field. The advances are so great though it is so new, it is pretty amazing. New things popping up all the time, like the information you share here. Your article just made me remember that podcast, so I thought I would share…
So true. And in each miniscule little area/body system, they’re learning new stuff every day! (Although much of it takes it back to good, whole living: clean air, clean food, good work, healthy relationships, etc.) Last night I was watching TV (yay!) about the Mayans, and they’re starting to think that they ran out of water after cutting down their trees in the jungle—it changed the rain amount and their cities weren’t located on rivers apparently. I look at those pyramids they built that light up “magical” looking creatures in the artwork on a particular day of the year and think about how brilliant they must have been in mathematics and astronomy and architecture— and then I think it came down to basics. Water and trees. Hmmm. History repeating? Nah. We’re too smart for that.
Warmest wishes for a grand upcoming weekend. A relaxing, homey one!
This summer I read most of ‘The Fragile Wisdom: An Evolutionary View on Women’s Biology and Health’ by Grazyna Jasienska. She maintains that fertility (hormone levels) and breast cancer are trade offs. Nature doesn’t care if you die of breast cancer when you are post-menopausal, so long as you’ve procreated.
I have not done any reading in regards to whether high estrogen women have more or less breast cancer than low estrogen women. I assume that based on where fat is stored (hips, thighs, butt) is an indicator of estrogen levels.
Statistics indicate that women who breastfeed have a lower incidence of breast cancer. I’d assume this is because prolonged breastfeeding of multiple offspring would also result in years and years of lower estrogen levels.
Low thyroid function = low fertility/high miscarriage rate. Are women with suboptimal thyroid function also having out of balance sex hormones as well? I have not looked into this but the fertility clinics need to check this sort of thing out.
BTW, I live in Toronto, Ontario. The test for reverseT3 was discontinued entirely in 2009. Pressure has been brought to bear on hospital endocrinologists to cease requests for fT3 as well. They claim it is notoriously inaccurate. ?? Back in the early 70s when I worked in medical labs (one at a hospital), PBI was the test for thyroid function. It was also ‘inaccurate’.
Seems to me (based on the removal of B12 as a tickable test…. must be written onto the requisition only if the patient exhibits neurological deficits! As if anyone even checks reflexes anymore! Full annual physicals are no longer done either. Apparently a waste of money. Patients are to self report when they subjectively notice something is not quite right in how they feel.) The Ministry of Health is taking a position that ‘Ignorance is bliss. If you don’t know that the patient has a problem, you don’t need to do anything about it.’ They stopped vitamin D testing as well because the highest available dose to the consumer is 1,000 IU. That amount will not take a patient from a deficit position. Repeat testing indicated that patients were not improving so instead of changing dosing recommendations, they canceled paying for the test instead. A study of University of Toronto students indicated severe vitamin D deficiency in a very high percentage of students. Even more alarming was the vitamin C study of undergrads: http://pepsico.ca/en/downloads/New_Study_finds_1_in_7_young_Canadian_adults_vitamin_C_deficient_ENGLISH.pdf Seriously? What does it take? Health Canada has come out with a position paper that taking vitamin supplements is not necessary for most people.
The majority of patients haven’t got a clue as to what is going on. I’m having to give B12 injections to the staff at work because FINALLY when B12 testing was done when one of them was unable to get up out of bed in the morning her level was so low. She’s just fortunate that the injections are working for her.
What very few people are aware of is that in Canada (not so much in the USA) milk is the most important source of dietary iodine. Statistics Canada published a study back in 2011 based on urinary iodine spot testing showing that up to age 18 most young people in the country are iodine replete. As people get older, they consume less dairy products and then after middle age they are being told to cut back on their salt intake (iodized). So over 40% of people over age 60 have suboptimal and deficient iodine status. They are being given statins and diuretics (poor kidney function = subpar thyroid), the kidneys aren’t getting enough energy so they raise the blood pressure and oops, the patient ends up on ACE inhibitors…. blahblahblah. Synthroid represents the highest number of prescriptions filled in this country. Since prescriptions are usually for 100 days, how many people could benefit from dietary modfications? But you KNOW full fat milk contains evil cholesterol. That message is really hard to kill. It’s like Whack A Mole.
One of my friends is a locum physician in small town northern Manitoba. An elderly woman (on all this polypharmacy) was admitted. Her daughter was told that mom had only a few days left. So the daughter convinced the physician (not my friend) to stop all the meds her mom has to pop seeing as how she’s going to die anyway. 2 days later the mom was dancing in the hallway. She was discharged with only Metformin left of all the meds she’d been taking. Damn scary stuff.
Was this a rant?
Good Morning, Gabriella!
“She maintains that fertility (hormone levels) and breast cancer are trade offs. Nature doesn’t care if you die of breast cancer when you are post-menopausal, so long as you’ve procreated.”
HA! That’s a nice, cynical point of view. (Perhaps nature doesn’t care because it knows divinity wants us sooner…?)
“Statistics indicate that women who breastfeed have a lower incidence of breast cancer. I’d assume this is because prolonged breastfeeding of multiple offspring would also result in years and years of lower estrogen levels.”
Yes, I suppose so. Unfortunately, on the other hand, it can cause some significant discomfort for the women as well, with vaginal dryness, low libido, headaches, mood changes. Such a balance.
“Low thyroid function = low fertility/high miscarriage rate. Are women with suboptimal thyroid function also having out of balance sex hormones as well? I have not looked into this but the fertility clinics need to check this sort of thing out.”
It seems like it goes both ways, too. Thyroid on the sex hormones. And sex hormones on the thyroid.
“The test for reverseT3 was discontinued entirely in 2009. Pressure has been brought to bear on hospital endocrinologists to cease requests for fT3 as well. They claim it is notoriously inaccurate. ?? Back in the early 70s when I worked in medical labs (one at a hospital), PBI was the test for thyroid function. It was also ‘inaccurate’.
Seems to me (based on the removal of B12 as a tickable test…. must be written onto the requisition only if the patient exhibits neurological deficits…They stopped vitamin D testing as well because the highest available dose to the consumer is 1,000 IU. That amount will not take a patient from a deficit position. Repeat testing indicated that patients were not improving so instead of changing dosing recommendations, they canceled paying for the test instead. A study of University of Toronto students indicated severe vitamin D deficiency in a very high percentage of students. Even more alarming was the vitamin C study of undergrads…”
This is all very disturbing. It’s not quite so bad here, but sometimes certain tests that you want will not be ordered, even if you order them. I can see it becoming quite the same as there over the next several years. A special call to the lab and also not running the tests through insurance may get you further. B12, vitamin D, thyroid tests. Biggies. Yes, they can be quite inaccurate, as can the cholesterol tests we order!!! But if used as a trending pattern with the patient’s history and exam in mind, all helpful stuff. The problem is, as you pointed out, we are getting further and further (and further and further) from our patients. We don’t touch them (by that I mean examine them!) and we don’t talk to them (because we’re too busy filling in government computer based programs that are required for us to be paid—-and as much as I’m a bleeding heart, people deserve paid for work). I’ll click over to the vitamin C study you linked to after I comment. If I click now, I’ll lose my comment. But that’s too bad. Glad your staff got theirs tested (B12).
“What very few people are aware of is that in Canada (not so much in the USA) milk is the most important source of dietary iodine…”
Even now in the States, our reproductive aged women are being shown to be iodine deficient. What bothers me most is that doctors aren’t aware of it, patients aren’t aware of it, and babies are being born under this state of low iodine. I feel like what they can detect in a study may just be the tip of an iceberg.
I’ve seen that story as well regarding the polypharmacy hospitalized patient getting better once all her meds were stopped (female in the case I know too). How many people out there are like that!?
We do have problems with medicine (as a field/practice). On the other hand, many patients are killing their bodies and the motivation to overcome and do what needs done is limited.
It is like Whack-a-Mole! Love that analogy. When one finally submits to the idea that whacking moles won’t do any good and that it needs a whole new overhaul, complete overhaul—when medicine and patients get that and follow that, we’ll finally have gotten somewhere.
Was it a rant? Probably classifies. Starts one place and finishes another, with a little sarcasm/cynicism thrown in. 😉 Are rants bad?