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

It’s well-documented that endocrine therapies like tamoxifen lead to uterine cancer in less than 1 percent of patients, Mouabbi points out. —Tom Gavin, EverydayHealth.com, 9 Sep. 2025

For example, mangosteen increases the effectiveness of tamoxifen, a drug commonly used for breast cancer.12 Supplement use should be individualized and vetted by a healthcare professional, such as a registered dietitian nutritionist (RD or RDN), pharmacist, or healthcare provider. —Amy Brownstein, Verywell Health, 7 Aug. 2025

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

Katie Hafner: The entire tamoxifen project went underground. —Katie Hafner, Scientific American, 31 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