Tamoxifen and similar drugs interfere with estrogen’s ability to stimulate the growth of breast cancer cells. Tamoxifen is prescribed for both pre- and post-menopausal women (and men). They slow or stop the growth of tumors by preventing cancer cells from getting the hormones they need to grow. Tamoxifen attaches to the receptor in the cancer cell and blocks estrogen from attaching to the cancer cell receptor.

Sources:

National Cancer Institute, 2022. Hormone Therapy for Breast Cancer