The Thyroid Breast Cancer Risk

A link between diseases of the thyroid gland and breast cancer was first noted in the early 1970s, since when there have been many expert articles. Some have linked people taking thyroid hormones with a higher risk of breast cancer (6). Others have questioned whether the culprit is low iodine lying behind both the poor thyroid performance and the breast cancer. There may even be a gut issue. For example, Turken et al (1): Women with breast cancer have higher levels of anti-thyroid peroxidase antibodies and the incidences of autoimmune and non-autoimmune thyroid diseases is higher in women with breast cancer. Auto-immune diseases are no known to start in the gut.

Ordinarily, you would expect people with sluggish dispositions and lower metabolic rates to have less cancer. In 2005 a team of researchers at the MD Anderson Cancer Center in Texas showed that women with lowered thyroid activity had less breast cancer by 61 per cent. Women with high thyroid activity developed more. And women with breast cancer were 57 per cent less likely to have hypothyroidism (that is where a person produces less thyroid hormone).

There also seems to be a breast cancer – thyroid cancer link. Rates of thyroid cancer are increased in women with a history of breast cancer, and vice versa (2).

Clearly there is a link, but it is not 100% clear whether it is one link or several, nor whether the link is direct or indirect. Many experts believe that the cause might be more to do with the gut as there seems to be links with Chronic Fatigue Syndrome and particularly Hashimoto´s which is usually dubbed an auto-immune disease because the immune system attacks the thyroid gland resulting in less thyroxine being produced. The medical solution is to prescribe a supplement of thyroxine, rather than treat the gut issue.

Chronic Fatigue Syndrome is now understood to be caused by an imbalance of gut bacteria and yeasts.

Go to: Chronic Fatigue Syndrome

Hashimoto´s has now been shown to be linked to Small Intestinal Bacterial Overgrowth, or SIBO.

Go to: Hashimoto´s Disease

Hashimoto´s is associated with a higher risk of thyroid cancer, in turn being linked to an increased risk of breast cancer.

The Treatment of Thyroid Disease

Your hormones are all linked in a finely balanced web. The technical name for this is homeostasis. Put one out and the rest will soon follow. Increase the levels of one, and some others will increase too, while some will decline. HRT is known to throw out hormone levels and leads to a three-fold increase in breast cancer risk, for example.

When we first published this article, we were written to by two separate American Doctors who commented thus:

If someone comes to us with sluggishness, tiredness, low energy, we would first look to gut problems. If we suspected a thyroid problem, first we would test for low iodine. We find this in about two-thirds of patients. Without iodine you simply don´t make enough thyroid hormone and the metabolism slows.

If iodine is not the issue, as a last resort we supplement with thyroxine. Once a person starts taking it, they are committed for life. You don´t start lightly. In fact, we prescribe different levels for different body weights and even change the dose by season, depending upon whether it is hot or cold weather.

None of the British women on thyroxin we come into contact with on Personal Prescriptions has ever been given an iodine test.

The Thyroid and thyroid hormones

The thyroid is an organ in the front of the neck and is shaped rather like a butterfly. The thyroid glands principal hormone is thyroxin, or thyroxine and this has a metabolic-rate-increasing effect on almost all of the tissues of the body. The University of Maryland has linked high levels of the hormone to excitable, hyperactive children and ADHD.

A lack of thyroid hormone (hypothyroidism) is associated with symptoms like a puffy face, tiredness, fatigue, and low energy. Other more rare symptoms include muscle cramps, hair loss, constipation, depression, memory loss and decreased libido. Since the metabolic rate declines, it is likely that the patient will also gain weight more easily.  Hypothyroidism in extremis can lead to changed (decreased) ovulation patterns in women and even loss of fertility. Equally, a number of pregnant women suffer from the disease but do not notice it, as fatigue is all too common anyway in pregnancy. One in seven women, and one in twenty men develop low thyroid hormone production as they age. Often they don´t even know it.  A simple blood test can be used for diagnosis.

The thyroid, in fact, makes two hormones – triiodothyronine (called T3) and thyroxine (T4). They are tyrosine-based hormones and both are partly composed of iodine. Tyrosine itself is a non-essential amino acid derived from the amino acid phenyialanine. It is essential in brain function because it is involved in neurotransmitter production – dopamine, epinephrine and norepinephrine. Tyrosine-kinase has now been linked with cellular energy systems, and cancer regulation.

Perhaps the oldest study(6) is the most relevant. The Ferdinand Sauerbruch Hospital in Wuppertal, Germany showed that women who took thyroxine had twice the risk of breast cancer. In the research amongst a group of women having screening mammograms – research that everyone seems to have ignored for 30 years – the incidence of breast cancer was twice as high in a group taking synthetic thyroxin for hypothyroidism. (12.1% in supplement group; 6.2% in controls). Worse, the incidence of breast cancer was far higher still where the women had taken synthetic thyroxin for more than 15 years (19.5%)

Thyroxine treatment plus low iodine causes breast cancer

Remember your problems could just be mineral dysregulation together with low iodine levels.

Maybe your first visit, if you are sluggish with no energy, should be to a Naturopath, who understands gut problems and Mineral Dysregulation.

At Thermography Clinic Ireland, we used both HTMA and Blood test to see exactly what is happening at a cellular level., and to discover the Root Cause of the mineral dysregulation.

Cranial Thermography is very useful when assessing the overall Health of the Breast Tissue. No proper asessment can be made of Breast Tissue without considering the Health of the  Thyoid gland, the head & Neck Lymphatics, Dental Health and indeed  Breast and underarm tissue, together mineral dynamics at a cellular level.





3. Hoffman, McConahey, Brinton and Fraumeni: Jama vol 251,1984

4. Cancer Epidem; 11, 1574-8 2002


6. Ghandrakant, C. et al Breast Cancer Relationship to Thyroid Supplements for hypothyroidism JAMA, 238:1124, 1976.

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