Thyroid function in postmenopausal breast cancer patients treated with tamoxifen

[anitab]

Anker GB, Lønning PE, Aakvaag A, Lien EA. Thyroid function in postmenopausal
breast cancer patients treated with tamoxifen. Scand J Clin Lab
Invest 1998; 58: 103–107.

Thyroid function was evaluated in 26 postmenopausal women with breast cancer
before and at various time intervals during treatment with tamoxifen. Tamoxifen
treatment suppressed plasma levels of FT3 and FT4 (p<0.005 for both) and
elevated plasma concentrations of TBG (p<0.005) and TG (p<0.025). In
general, these changes became significant after 6 months of treatment. Plasma
TSH increased significantly after 1 y of treatment (p<0.025). A fall in FT4 and
FT3 combined with increase in TSH suggests a reduced bioavailability of T4
and T3 during tamoxifen treatment. The increase in TG may reflect a reduced
synthesis or liberation of T4 resulting in a reduced plasma level of FT4. Our
findings suggest that tamoxifen influences the thyroid hormone levels, not only
by modulating plasma TBG, but also by interfering with hormone synthesis or
secretion in the thyroid gland.

This is the abstract from a small study. I don't have the link, unfortunately.

Anita

[rentrac]

The thyroid gland is a touchy little thing. It's notorious for getting easily stressed during acute illnesses, and it can take a while to recover. At least somebody looked at the effect of Tamoxifen on the gland, because long term effects of a drug on the thyroid function are not always done or published. Having had my own run-ins with this gland over the years, I'm convinced the very best way to deal with any thyroid condition during cancer treatment is with an endocrinologist, as that's the specialty that truly knows how to manage it.
Here's to normal TSH for all,
Rentrac

[Hopeful]

I am wondering if this effect is Tamoxifen specific, or would also be the result of "natural" SERMS like flaxseed that some of us use in our diets? I had elevated TSH results prior to dx when I was taking flaxseed tablets, which I stopped prior to dx. I had my thyroid retested following radiation therapy, and all results were normal.

Hopeful

[dhealey]

I had an elevated TSH about 6 months prior to my bc diagnosis and was put on synthroid. I did some research when I was diagnosis about the affects of tamoxifen on the thyroid before I ment my oncologist and I was dead set against taking it because of what I had read in my research. I told the oncologist about this and she kind of brushed it off and wanted to start me on tamoxifen after my chemo treatments, but blood test revealed I had been through menopause so I was started on arimidex instead have now switched to aromesin instead due to severe joint pain. I had allready decided I wasn't going to take the tamoxifen anyway because of it's effects on the thryoid since mine was already out of wack.

Rentrac what part of North Carolina are you from? I live in Lexington. Good to know a breast cancer sister in my state.

[rentrac]

I live in Blounts Creek, but I'm only half flat-lander as my dad's family is from the Brushy Mountains - Lenoir, Wilkesboro, etc. I even used to live in the village of Grover - a spot in the road where I-85 crosses from NC to SC. Amazing how many of us Carolinians there are on this site - I prefer to think of it as our being smart and having good taste rather than too many of us in this kettle of fish!
Rentrac

[Lani]

how many of those patients had radiation therapy also--which perhaps can affect the thyroid gland and, thus, how much was the effect of the tamoxifen alone and how much might have been due to the radiation therapy or the combination of the two...

Just food for thought

[Joanne S]

The link is

http://www.ingentaconnect.com/content/tandf/scli/1998/00000058/00000002/art00002

[Joanne S]

Topic: Breast Cancer, Tamoxifen, Thyroid & Weight Loss
I found another link on this subject:

http://thyroid.about.com/library/derry/bl1a.htm

[mom22girlz]

Thank you for this thread. I am struggling with this issue and my doctors. My onc says NO WAY does tamoxifen cause weight gain in any way. I have gained 17 lbs since I started tamoxifen. (about 18 mo.) I have been taking thyroid meds for about 2 mo now with no effect on my weight. I don't really know what to do. When does the extra weight start to affect the chance of reoccurance if you are estrogen positive? Thanks for any input. susan