Thyroid Hormone Therapy
Appears to Cause Breast Cancer
by Dr. James Howenstine, MD
Medical journals and textbooks typically portray iodine as an unimportant
substance which should be taken in small amounts[1] because of it's
dangers. Actually approximately one third of humanity has iodine deficiency.
When humans lack iodine the thyroid gland enlarges (goiter), nodules appear
in the thyroid gland and over a period of time cancer may appear in a
thyroid nodule. Conventional medicine treats thyroid gland enlargement
with thyroid hormone without considering the possibility that the hypothyroidism
and goiter may be due to lack of iodine. This failure to diagnose and
treat iodine deficiency can lead to an increased risk of breast cancer
and the longer the diagnosis is missed the greater the chance that breast
cancer will occur. Women taking thyroid hormone appear to be twice (12.1%)
as likely to develop breast cancer as women not using thyroid hormone
(6..2%). Women who had taken thyroid hormone for 15 years had a 19.5%
incidence of breast cancer whereas women who have only taken thyroid hormone
for 5 years had only a 10% incidence of breast cancer. Why is this?
The essential trace element iodine may be the most important least publicized
mineral in existence. Iodine is the only element needed in hormones and
in the production of hormones. The iodine containing hormones are involved
in the creation of embryos, development of brain function, growth, metabolism
and maintenance of body temperature. This means that proper amounts of
thyroid hormone, estrogen, progesterone, testosterone, insulin, growth
hormone etc. can not be made when iodine is lacking from the body. One
third of all individuals on Earth are functioning with subnormal levels
of iodine. Low intake of iodine is the leading cause for intellectual
deficiency in the world.
There is strong evidence that iodine lack predisposes to breast cancer.
One out of seven women in the US has deficiency of iodine proven by urine
iodine screening tests (urine I less than 50 ug/L). This is the same incidence
for breast cancer seen in US women. Without bothering to check urine for
iodine, physicians visited by a woman with a goiter or symptoms of hypothyroidism
are routinely prescribing thyroid hormone therapy.
Hintze et al[2] compared the results of 400ug/L of Iodine with 150ug of
T4 (synthyroid) for 8 months and then four months after stopping therapy.
The results clearly favored iodine therapy. Both treatments led to similar
suppression in the size of the goiter. However, four months later the
size of the thyroid had returned to pretreatment levels in the group treated
with T4 hormone. The group who had received iodine therapy continued to
have normal sized thyroid glands four months after therapy was stopped.
Several investigators have concluded that iodine lack is a probable cause
for breast cancer in women.[3] [4] [5] [6] [7]
Demographic studies in Japan and Iceland revealed that both countries
have a high intake of iodine and low incidences of goiter and breast cancer.
In Mexico and Thailand where iodine intake is low there is a high incidence
of goiter and breast cancer.[8] Thyroid gland size measured by ultrasound
is significantly larger[9] in Irish women with breast cancer than control
women.
Administration of thyroid hormone to iodine deficient women appears to
increase the risk of developing breast cancer. In a group of women undergoing
screening mammograms the incidence of breast cancer[10] was twice as high
in the women taking thyroid hormone for hypothyroidism (probably caused
by iodine lack) than in women not taking thyroid supplements. The mean
incidence was 6.2% in controls and 12.1% in women on thyroid hormones.
The incidence of breast cancer was twice as high in women taking thyroid
hormone for more than 15 years (19.5%) compared to those on thyroid hormones
for only 5 years (10%).
In the state of Michigan, during a period of iodine supplementation in
bread (1924-1951) the prevalence of goiter diminished from 38.6% to 1.4%.
Of interest the incidence of breast cancer remained unchanged during this
time frame. This information was used to suggest that iodine supplementation
had no effect on the incidence of breast cancer. However, Ghent and Eskin
were able to show in women and female rats that the amount of iodine needed
to protect against fibrocystic disease of the breast and breast cancer
was at least 20 to 40 times greater[11] than the iodine needed to control
goiter.
In the 1960s mandated iodine containing dough was equivalent to the RDA
of 150 ug per slice of bread. At that time the incidence of breast cancer
was only 1 in 20.[12] In the past 20 years the use of iodine supplementation
in bread was eliminated and a goiter producing substance toxic to the
thyroid gland (bromine) was introduced as replacement for iodine. The
risk for breast cancer is now 1 in 8 and this risk is increasing by one
percent[13] each year. The decision to replace iodine in an iodine deficient
population with a goitrogen was illogical lacking in common sense. The
damaging effects of bromine on thyroid tissue also appears to contribute
to the development of autoimmune diseases in the thyroid gland (Hashimoto's
thyroiditis).
The mammary glands have a trapping system for iodine similar to that of
the thyroid gland. The breasts effectively compete with the thyroid gland
for ingested iodine. This distribution of iodine to both breast and thyroid
gland in pubertal girls explains why goiter is 6 times more common in
girls than pubertal boys. The disappearance of iodine into breast tissue
in women leads to decreased ability to supply the thyroid gland with an
adequate amount of iodine. The development of a goiter in young girls
indicates deficient distribution of iodine to both breast and thyroid
tissue. Treating such a patient with thyroid hormone is not sensible and
appears to increase the risk of breast cancer.
Study of radioiodine uptake in normals and women with fibrocystic breast
disease FDB reveals that the FDB breasts were able to take in 12.5% of
the iodine dosage compared to only 6.9% in normal breasts. This proves
the existence of considerable iodine depletion in the breasts of women
with FDB.
There is considerable evidence for an increased risk of thyroid cancer
as well as breast cancer in persons with iodine deficiency. Untreated
iodine deficiency leads to goiter, thyroid nodules and eventually some
of these nodules become malignant. The decreasing intake of iodine has
resulted in an increase in thyroid nodules and increase in thyroid cancer.
In 2001 there were 19,500 new cases of thyroid cancer in the US with 14,900
of these cases occurring in women.
Iodine has a role in promoting general well being as well as protecting
against infections, degenerative diseases and cancer. Iodine promotes
the normal killing of defective and abnormal cells (apoptosis). Thus,
iodine helps the body's surveillance system to detect and remove abnormal
cells. Additionally, the presence of iodine triggers differentiation away
from the more dangerous undifferentiated type of cell toward normal cells.
The presence of adequate levels of iodine in the body (Japanese diet with
lots of sea vegetables and fish) reduces reactive oxygen species (ROS).
in the body which decreases the oxidative burden in the body This results
in slowing of degeneration disease processes and decreasing the risk of
cancer.
Nearly every physician in the United States will reach for a prescription
pad to order thyroid hormone when he sees a patient with goiter or symptoms
of hypothyroidism. This can be exactly the wrong thing to do if the patient
has deficient stores of iodine. Insist on obtaining a 24 hour urine collection
for iodine to eliminate iodine lack as the cause for your symptoms (values
below 50 ug/liter are abnormal). Thyroid hormone therapy in the presence
of iodine deficiency increases the risk of breast cancer and probably
thyroid cancer as well. Endocrinologist, Dr. Guy Abraham, formerly of
the U.C.L.A. Department of Endocrinology, is convinced that everyone needs
to be on iodine therapy until their iodine stores have been fully restored.
After this time frame periodic intake of iodine will help insure that
the many body functions requiring iodine run smoothly.
A dosage of two tablets of Iodoral twice daily for three months followed
by one Iodoral tablet daily for a year will restore iodine stores for
most persons. At that point periodic taking of an Iodoral tablet daily
one month out of 4 to 6 months etc. will be adequate to maintain iodine
stores. Iodine stores can be easily monitored by taking 4 Iodoral tablets
(50 mg iodine) and collecting a 24 hour urine sample for iodine content.
If 80% of the ingested iodine is found in the urine collection the iodine
stores are normal. Iodoral can be obtained from Optimox Corp. Torrance,
Cal. To purchase a referral from a health care practitioner is needed.
Footnotes:
1. Abraham, Guy F. et al Orthoiodosupplementaion: Iodine Sufficiency Of
The Whole Body pg 1
2. Hintze, G. et al treatment of Endemic goiter due to iodine deficiency
with iodine, levothyroxine or both:results of a multicentre trial. European
Journal of Clinical Investigation, 19:527-534, 1989
3. Eskin B et al Mammary Gland Dysplasia in Iodine Deficiency JAMA , 200:115-119.
1967
4. Eskin B Iodine and Mammary Gland Cancer Adv. Exp. Med. Biol., 91:293-304,
1977
5. Ghent, W. et al Iodine Replacement in Fibrocystic disease of the Breast
Can. J. Surg. , 36:453-460, 1993
6. Eskin B. et al Different Tissue Responses for Iodine and Iodidein Rat
Thyroid and mammary Glands Biol. Trace Element Research 49:9-19, 1995
7. Derry , D Breast Cancer and Iodine Trafford Publishing, Victoria B.C.
, 92, 2001
8. Finley JW., Bogardus, G.M., Breast Cancer and Thyroid Disease Quart.
Review Surg. Obstet. Gyn. 17:139-147, 1960
9. Smtyhe, P. , Thyroid Disease and Breast Cancer J. Endo. Int. , 16:396-401,
1993
10. Ghandrakant, C. et al Breast Cancer Relationship to Thyroid Supplements
for hypothyroidism JAMA, 238:1124, 1976
11. Backwinkel, K., Jackson, A.S. Some Fearures of breast Cancer and Thyroid
Deficiency Cancer17:1174-1176 , 1964
12. Epstein, S.S., Sherman, D. Breast Cancer Prevention Program Macmillan
, NY. 1998 pg 5
13. Ibid
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