- Question from Website Question: What is the effect of tamoxifen on fertility?
Kutluk Oktay, M.D.
Tamoxifen does not have any permanent effects on fertility, even though some claims have been made. However, while taking tamoxifen for breast cancer treatment, because it constantly stimulates the ovaries, it can result in ovarian cysts and may make the ovary temporarily dysfunctional. It may increase fertility for a time, but reduce it later, because it's being used constantly, as opposed to the way it's used in fertility treatments, which is usually at high doses for five days.
But once you stop taking tamoxifen for breast cancer treatment, ovarian function is expected to go back to where it was before, which is unlike chemo drugs. Tamoxifen does not reduce ovarian reserve beyond what happens with age.
- Marisa C. Weiss, M.D. That's a good point, since some women may be on tamoxifen for up to five years, so age can have a significant impact on fertility if taken that long.
- Leslie R. Schover, Ph.D. Another concern is that tamoxifen may at least theoretically cause birth defects if taken during pregnancy. So while women are taking tamoxifen, they are advised to use birth control and avoid getting pregnant.
- Kutluk Oktay, M.D. Excellent point. Even though there are few case reports and the abnormalities don't resemble each other, tamoxifen should still be avoided during pregnancy.
On Wednesday, August 18, 2004, our Ask-the-Expert Online Conference was called Pregnancy and Fertility Issues. Kutluk Oktay, M.D., Leslie Schover, Ph.D., and moderator Marisa Weiss, M.D. answered your questions about pregnancy and fertility before, during, and after breast cancer treatment, as well as the options of adoption and gestational carriers (surrogate mothers).
The materials presented in these conferences do not necessarily reflect the views of Breastcancer.org. A qualified healthcare professional should be consulted before using any therapeutic product or regimen discussed. All readers should verify all information and data before employing any therapies described here.
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