Chlorotrianisene (INN, USAN, BAN; brand names Tace, Estregur, Anisene, Clorotrisin, Merbentyl, Triagen, many others; also known as CTA; tri-p-anisylchloroethylene, TACE, or tris(p-methoxyphenyl)chloroethylene) is a synthetic, non-steroidal estrogen of the triphenylethylene group that was formerly used for the treatment of menopausal symptoms, estrogen deficiency, and prostate cancer before being discontinued.