tamoxifen

noun

ta·​mox·​i·​fen tə-ˈmäk-sə-ˌfen 

: an estrogen antagonist C₂₆H₂₉NO used in the form of its citrate especially to treat postmenopausal breast cancer

Examples of tamoxifen in a Sentence

Recent Examples on the Web

In general, though, the risk of uterine cancer from tamoxifen use is low. — Carrie Madormo, Health, 13 July 2025

Thank you, Dora, on behalf of all the women tamoxifen has helped, and all the women tamoxifen will help. — Katie Hafner, Scientific American, 31 Oct. 2024

After a moment’s thought, Greenwald told her to do the lumpectomy—and the tamoxifen, which would cut the chance of cancer recurrence in half. — Melanie Thernstrom, New Yorker, 29 June 2026

Additionally, the results may guide the use of hormonal therapies, such as tamoxifen, for estrogen receptor-positive cancers. — Sandra Rose Salathe, Flow Space, 3 Oct. 2024

Word History

Etymology

probably by recombination & alteration of trans-, oxy, and clomiphene

First Known Use

1972, in the meaning defined above

Medical Definition

tamoxifen

noun

ta·​mox·​i·​fen ta-ˈmäk-si-ˌfen 

: a selective estrogen receptor modulator that acts as an estrogen antagonist in breast tissue and is administered orally in the form of its citrate C₂₆H₂₉NO·C₆H₈O₇ especially to treat breast cancer or reduce the risk of its development or reoccurrence see nolvadex