FPGEE for NABP 2025 – 400 Free Practice Questions to Pass the Exam

Tamoxifen and toremifene are both classified as selective estrogen receptor modulators (SERMs) and act as estrogen antagonists in breast tissue. These medications are primarily used in the treatment of hormone receptor-positive breast cancer. By competing with estrogen for binding to estrogen receptors on breast cancer cells, they help to inhibit the growth of these tumors, which often rely on estrogen to proliferate.

Tamoxifen has been a cornerstone in the management of breast cancer for decades, particularly in premenopausal women, whereas toremifene is often used in postmenopausal women with metastatic breast cancer. Both agents have demonstrated effectiveness in reducing the risk of cancer recurrence and improving survival rates in patients with estrogen receptor-positive tumors.

The other options provided include medications that do not primarily function as estrogen antagonists for the treatment of breast cancer. Clomiphene is used to induce ovulation, norethindrone is a progestin used in contraceptives, aromatase inhibitors work by reducing estrogen production rather than blocking its action at the receptor, and ethinyl estradiol and mestranol are forms of estrogen used for hormone replacement therapy or contraception, rather than as antagonists in the context of breast cancer.