Log in to post a reply
Jul 14, 2018 07:59PM
Jul 14, 2018 10:29PM
Progesterone and breast cancer is an interest of mine. I've discovered that it's a complex subject that is not yet very straight forward.
Certain progestins had been used in the past to treat breast cancer but I can find little information on it. One of them was medroxyprogesterone acetate, which is ironic because that is the progestin implemented in an increase of breast cancer rates in post menopausal women who took HRT to alleviate symptoms of menopause.
Here is one of the few studies I found on the use of medroxyprogesterone in the treatment of breast cancer.
Oral medroxyprogesterone acetate in the treatment of metastatic breast cancer.
As an aside...it seems that not all progestins affect breast cancer risk and breast cancer proliferation equally. Unfortunately many studies do not differentiate between different progestins, but here is a study that sought to distinguish the risk from micronized progesterone (bio identical) from synthetic progestins if you are interested.
The impact of micronized progesterone on breast cancer risk: a systematic review
It should be noted they are talking about risk of developing breast cancer, and not the actual effect on already existing breast cancer.
To continue with using progestins to treat breast cancer...
There is renewed interest in treating ER+/PR+ breast cancer with progestins, this time I believe bio identical progesterone and there are three clinical trials planned or already under way. The idea is that in hormone receptor positive breast cancer, the progesterone receptors are attached to the estrogen alpha receptors, and when activated, interfere with the ability of the estrogen alpha receptors to be activated.
Progesterone receptor modulates ERα action in breast cancer
Here is a nice article on that paper.
Solving a breast cancer mystery – why do 'double-positive' women do better?
Here is a link to one of the clinical trials involving progesterone therapy in breast cancer. They are not including people with stsge IV in it but those running the trial might have some information or resources that could be of help.
A trial looking at progesterone to treat early breast cancer in premenopausal women
I should mention something though concerning progesterone and HER2 positive status. I am by no means an authority on this matter, I just came across this in my own personal research...HER2 receptors are activated and cause tumor proliferation by the activation of other HER receptors, particularly HER1 which is also called EGFR. One of the things that activates HER1 is a compound called amphiregulin, and one of the things that causes the expression of/interacts with amphiregulin is progesterone. I cannot say what the implications are of this, but being HER2 positive, I would be concerned that activation of HER2 receptors by this mechanism, in the presence of exogenous progesterone use, would negate any anti proliferative effects that the progesterone exerts through alpha progesterone receptor inhibition. I would love to find someone who could give me an answer to this someday.
The only thing I have right now are a few papers on amphiregulin, progesterone, estrogen, and breast development and a paper the concluded that amphiregulin confers herceptin resistance in HER2 positive breast cancer.
Amphiregulin confers trastuzumab resistance via AKT and ERK activation in HER2-positive breast cancer.
I think we will see studies that better investigate the relation between these things in the future though.
One more thing. One study I found observed a bi phastic effect of progesterone on breast cancer. In some instance they observed cell proliferation and in other inhibition.
Biphasic Regulation of Breast Cancer Cell Growth by Progesterone: Role of the Cyclin-Dependent Kinase Inhibitors, p21 and p27Kip
A general disclaimer for the general public: As always, take these studies with a grain of salt. We aren't mice or petri dishes. Research is a discover process. Conclusions are tentative and sometimes subjective. Biology is complex. And researchers aren't infallible. And make sure your doctor is aware of and onboard with any treatments, medical or alternative that you embark on.
Edit: I just noticed that the website the paper on medroxyprogesterone as a treatment for metastatic breast cancer has links to more papers on the matter. One details it's use in ER+/PR+ breast cancer specifically.
Pathologic complete response (pCR) to chemotherapy.
2018, IDC, Left, 3cm, Grade 3, ER+/PR+, HER2+ (FISH)
6/1/2018 Carboplatin (Paraplatin), Taxotere (docetaxel)
11/15/2018 Lymph node removal: Left, Sentinel; Mastectomy: Left, Right; Reconstruction (left): Tissue expander placement; Reconstruction (right): Tissue expander placement
Tamoxifen pills (Nolvadex, Apo-Tamox, Tamofen, Tamone)
Reconstruction (left): Silicone implant; Reconstruction (right): Silicone implant