Tamoxifen is a compound used in breast cancer research and estrogen-related gynecomastia. It is a selective estrogen receptor modulator (SERM) and reduces growth of breast cancer cells, aling with its metabolite 4-hydroxytamoxifen. This member of the triphenylethylene group was initially manufactured in 1962 by chemist Dora Richardson (ICI, now part of AstraZeneca) and called Compound ICI 46,474. It was part of a project to design a new contraceptive pill but it was found to stimulate rather than suppress ovulation and was re-purposed to become the first preventative for any cancer. Without the efforts of the team lead and reproductive endocrinologist Artur Walpole, it may have not been pursued further. It was not until 1998 that the meta-analysis of the Early Breast Cancer Trial Collabrative Group showed that it was effective for early breast cancer. Structurally, it is closely related to other triphenylethylenes like clomifene, nafoxidine, ospemifine, toremifene, and others.
