Tamoxifen is a pharmaceutical drug (Novaldex) given to premenopausal women with estrogen positive breast cancer.
Tamoxifen can also be used in prevention for women at high-risk of developing breast cancer or used in fertility treatment.
It’s main task with breast cancer is to block estrogen receptors on tumour cells. This stops the growth of cancer, in the breast and in the body.
A less known fact among women with breast cancer, is that tamoxifen raises estrogen and progesterone levels in the body.
This seems counteractive to me.
In 2008, a collaborate paper between the top American cancer centres determined that increased estradiol (E2) is significantly associated with a risk of cancer recurrence.
As a side note, there are four main naturally occuring estrogens in women: Estrone (E1), estradiol (E2), estriol (E3), and estetrol (E4).
Each estrogen hormone is most active during the following times:
- E1 menopause
- E2 reproductive years
- E3 pregnancy
- E4 pregnancy
On top of that, the increased levels is though to contribute to tamoxifen resistance.
So I would like to know why that when I asked my first oncologist if they would be testing my hormone levels… she answered: No.
For now, I will be testing my hormone levels with urine and serum.
I started testing my hormone levels after my initial diagnosis. I test my hormones after all major changes: My diet, after starting tamoxifen, and through changing different supplements.
My ultimate goal is to see my hormones become balanced.
I am not happy with the wait and see approach, this would mean that I would have to wait for recurrence to know if tamoxifen actually worked.
CYP2D6 gene mutation
There is also another aspect aside from hormones that causes tamoxifen resistance.
This can be tested by buccal swab (mouth swab) done by your physician. The companies name is Genelex located in the USA.
I have not yet done this testing but will be ordering it and will let you know the results!
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