Tamoxifen, Menstruation, and Age

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McClure77
McClure77 Member Posts: 55
edited April 2016 in Hormonal Therapy - Before, During, and After

Hi Everyone,

It looks like, out of the blue, I may have started menstruating again yesterday. This is a surprise because my drs all seemed to think that I would stay in menopause between the chemo and the tamoxifen. While I have read that many people still have cycles while taking tamoxifen, it raises a lot of questions. If the way that tamoxifen works is that it stops estrogen from binding to cancer cells, then why would estrogen still be in use by other systems in the body? (Plus it does beg the question about why we can block what a cancer cell is able to feed on, but not block the cancer cell itself, which seems weird....) Obviously, if I really am back to regular cycles, it means my body has been able to rebuild enough supply of estrogen to restart the whole process. If that estrogen is available to my ovaries and uterus, why would it be unusable to cancer cells, and how could that work with any degree of certainty? This is where the age part also comes into play. I've also read that tamoxifen works less well on women in their 30's and 40's and really works the best for women over 55. If that is true, might that also be because of levels of estrogen are obviously stronger in younger women? And what does that really mean? Thoughts? Experiences?

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  • Goodie16
    Goodie16 Member Posts: 446
    edited March 2016

    When I was on tamoxifen, I had regular cycles the entire time. My onc was not concerned about this in the least.

    Tamoxifen doesn't really stop the production of estrogen but rather prevents the estrogen from being able to bind to the cancer cells and feed them. So the estrogen that is going to your ovaries and uterus aren't effected by the tamoxifen, but any cancer cells that need estrogen are getting tamoxifen instead. Does that make sense?

    This a good read on tamoxifen: http://www.imaginis.com/breast-cancer-treatment/ba...


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  • McClure77
    McClure77 Member Posts: 55
    edited March 2016

    Sorry I replied last week but I don't see it here so I must not have clicked submit!


    I understand that Tamoxifen doesn't stop your estrogen production, but I guess my oncologist was certain that I was in menopause now. I'm wondering if now we are going to have to talk about ovarian suppression since obviously my body is determined to keep kicking. I guess they would never do ovarian suppression with Tamoxifen if doing it alone were always enough, right? It's funny because I had just asked my oncologist about hormone levels and why they aren't testing to see what mine were. I think our confidence levels might be reduced now ;)

    I was told to stop the tamoxifen and within a couple of days of stopping it, I also stopped bleeding. I don't know if that would have happened anyway, but it seems interesting. I'm having surgery in a few weeks and I've read that stopping it before surgery is a good idea, so perhaps it's a two birds with one stone thing :)


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  • etnasgrl
    etnasgrl Member Posts: 650
    edited March 2016

    I am 41 and on Tamoxifen. I asked my MO a lot of questions prior to starting it.....

    He told me that Tamoxifen should not cause me to go into menopause and if it does, he would be very surprised. He explained that Tamoxifen only blocks estrogen in the breasts and actually creates more estrogen in the uterus, which explains why uterine cancer can be a side effect of Tamoxifen. I have uterine fibroids and he told me that there is a very good chance that the Tamoxifen will make the fibroids worse, since they need estrogen to grow. He expects my periods to get heavier, not lighter.

    I don't know where you read that Tamoxifen works better for women over 55, but that's not true. It is safer for women under 50, who are still menstruating, to be on Tamoxifen.

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  • McClure77
    McClure77 Member Posts: 55
    edited March 2016

    Etnasgrl: There are several sources, but here is one of them: http://www.imaginis.com/breast-cancer-treatment/ba...

    It's about halfway down under the heading "Who is a candidate for Tamoxifen Therapy?"


    "Several studies have also shown the benefit of tamoxifen in preventing breast cancer is age-related. Women under 40 years of age typically show the least response to tamoxifen, women between the ages of 40 and 50 years of age show some response, and women over 50 typically benefit most from tamoxifen. In fact, early-stage breast cancer patients over 50 years of age who are treated with tamoxifen may be able to significantly reduce (or sometimes completely eliminate) the size of their breast tumors so that surgeons may perform lumpectomy instead ofmastectomy. Researchers are not certain why young women do not respond as well to tamoxifen but believe it may be related to the amount of estrogen produced in their body. When a woman reaches menopause (typically around 50 years of age), her body stops producing estrogen."


    I'm not sure why my oncologist was so sure I was already in menopause. My mother was having children well into her 40's and didn't go into menopause until MUCH later. However, I'm also not sure if her concern about the levels of estrogen now would be greater due to my advanced diagnosis. Obviously, if Tamoxifen only works in the breasts, then it's only protecting my breasts, not any other areas in which the cancer could metastasize. Honestly, I'm LESS worried about my breast than I am about my brain, lungs, liver and bones. Those are all common areas for breast cancer to recur and none of them is as easily removable as a breast is! So if Tamoxifen is not protecting these assets, then something probably should be!


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  • etnasgrl
    etnasgrl Member Posts: 650
    edited March 2016

    I've often thought of that too. I asked my MO about Tamoxifen protecting the brain, liver, bones, etc. and he said no, it only protects the breast. It reduces the chance of recurrence in the breast and reduces the chances of getting a new primary in either breast.
    That's wonderful.....but like you said, what about the other places? I don't know.
    It's not a promise that the cancer won't come back, but it's something we can do to hopefully prevent it. There isn't much else we can do.

    Thanks for the links on Tamoxifen for older women. Everything I've read, including Dr. Love's Breast Book, says the exact opposite. It's interesting to see how different sources say different things. Makes you wonder who is right!
    I do know that even after menopause, women still produce estrogen, it doesn't stop all together. They just produce LESS estrogen than they did before, so that quote is wrong.....at least about that.

    Anyway....I guess the best we can do is ask lots of questions, find an oncologist we can trust, and do whatever we can to prevent a recurrence. Honestly, in my opinion, cancer is a crap shoot. I know of women who ate "clean", exercised every day, and still got breast cancer. I also know of women who ate crap all the time, hardly moved, and are in their 70's, with no breast cancer.
    Like I said, I believe it's a crap shoot.

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  • ShetlandPony
    ShetlandPony Member Posts: 4,924
    edited March 2016

    I think I can contribute a missing piece to this discussion. As I understand it, tamoxifen blocks estrogen from binding to breast cells, whether they are normal breast cells or evil mutated cells. This is why, I believe, that tamoxifen took away the cyclical breast soreness I used to experience as a pre-menopausal woman: no estrogen stimulating any breast cells. Now, if there are renegade breast cancer cells in another part of the body, they are still breast cells and are still affected by tamoxifen, which should prevent their feeding on estrogen. That is why tamoxifen can work to shrink mets in bone, liver, etc. So McClure, it ought to be protecting other areas as well as the breasts. As etnasgirl notes above, while tamoxifen blocks estrogen from some types of cells such as breast, it can stimulate other types of cells, such as uterine.

    For the question of when tamoxifen plus ovarian suppression would be recommended, see the SOFT trial results. For premenopausal breast cancer patients, it compared tamoxifen alone, tamoxifen plus ovarian suppression, and an aromatase inhibitor plus ovarian suppression.

    http://www.breastcancer.org/research-news/ovary-su...


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  • etnasgrl
    etnasgrl Member Posts: 650
    edited March 2016

    ShetlandPony.....thank you so much for that explanation!!! That makes total sense. If breast cancer metastasized to the liver, lungs, brain, etc., it is still called "breast cancer". So, it would make sense that Tamoxifen can still have an effect on them.
    I guess when I asked my MO about this, I didn't word it the right way and he thought I meant if I happen to get cancer, (like a new primary), somewhere else in my body, unrelated to the breast cancer.

    I feel a lot better now! Thanks again!

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  • ShetlandPony
    ShetlandPony Member Posts: 4,924
    edited March 2016

    Exactly.You're welcome. 😀

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  • McClure77
    McClure77 Member Posts: 55
    edited April 2016

    Well, turns out that I have a bunch of cysts and abnormal thickening of my uterine lining now, so they are wanting a total hysterectomy to be as safe as possible. It's logical, but I'm still having a hard time with it, and everything it will mean. Thanks for your responses!

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