No Side Effects from Tamoxifen (Nolvadex)? Why It May Not Be Working

Does anyone have any idea how estrogen levels relate to tamoxifen efficacacy, if at all? I had an ER positive tumor taken out late in '06 (when I was 44, premenopausal) , chemo, radiation and have been on tamoxifen for a year. AFter the chemo I was slipping into menopause (I had a previous partial hysterctomy so no menstration anyway) but the hot flashes were intense. Turns out my estrogen level at the start of tamoxifen (March) was around 14. Eight months later in November it ws 15. Now, suddenly in Februrary it's up to 391 and my hot flashes have stopped. I was confused when my oncologist said he wasn't too concerned. We discussed removing my ovaries but he said "nothing I know convinces me we need to do this." So my question (since estrogen levels is something they're obviously measuring) is what does that tell them? does it relate to tamoxifen? if my ovaries have sprung back to life,  do we just assume that the tamoxifen is blocking that estrogen? how can you tell if it's working or not? Anybody?

 

 

Shelly, I'll tread VERY gingerly here, since I have absolutely no medical training. So take this for what it's worth: an informed opinion. From what I understand tamoxifen has nothing to do with the production of estrogen in your body; your body is going to produce it so long as your ovaries are still working. Perhaps your treatment turned off your ovaries for awhile, but now they've come roaring back. From what I understand, tamoxifen blocks estrogen from linking up with breast cancer cells; and since ER-positive breast cancer cells need estrogen to grow and proliferate, tamoxifen effectively blocks this from happening. I would think one thing you might do is explore further the testing Lila is talking about; that way, you could at least rule out tamoxifen not being metabolized in your body, and therefore being an ineffective treatment for you. Good luck- PJH

Lila,

 

Once again, thanks for your research into this topic. I am considering scheduling a consult at the Mayo Clinic (I live an hour away in MN) to discuss the possibility of interaction between tamox and bupropion (generic for Wellbutrin). When I met with my oncologist, all he really had for me was a 2-paragrpah printout from their pharmacology dept. that suggests that bupropion has a low interaction effect with tamox The (very) few pieces of research I have found that discuss bupropion specifically suggest it is a strong inhibitor of tamox metabolization. However, my oncologist was very clear with me that even if it was discovered that I couldn't metabolize tamoxifen at all (i.e. I have deficient or missing enzymes to do so, regardless of other medication interactions), he would not recommend any change in treatment. He cautioned multiple times that much of this research is based on studies with low numbers of women, which is true. He also suggested that the fact that I am experiencing any side effects (whether or not they may seem milder than what others experience) suggests that the tamox IS being metabolized. At any rate, I am guessing that I won't get any different treatment recommendations as far as the tamox is concerned (I'm pre-menopausal), but I still feel like I haven't gotten the most informed information re: whether or not I should try switching my antidepressant.

 

Thanks for your continuing research on this important topic! Jolene

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