NCIt definition : A tamoxifen metabolite with both estrogenic and anti-estrogenic effects. Afimoxifene
has a higher affinity for the estrogen receptor than tamoxifen, and functions as an
antagonist in breast cancer cells.;
Alternative definition : NCI-GLOSS: A form of the drug tamoxifen that is made by the body after taking tamoxifen.
It can also be made in the laboratory, and may help decrease breast density. A topical
form of 4-hydroxytamoxifen is being studied in breast cancer screening.;