Abstract

PIP: Tamoxifen (ICI 46474) is the trans-isomer of 1(p-beta-dimethylaminoethoxy-phenyl)-1, 2-diphenylbut-1-ene. In several but not all mammal species it is a potent anti-estrogen. It is thought to act by blocking estrogen receptors. Patients were 68 women with advanced primary carcinoma of the breast, recurrences in the chest wall or soft tissue metastases. The oral dose of tamoxifen was either 10 mg or 20 mg twice daily. Patients were seen and laboratory tests done monthly for 6 months. Side effects were usually trivial and their incidence was the same at both dose levels. Of 26 patients who showed a reduction in tumor size to half or less, 5 had been in remission for over a year and another 10 for over 6 months. Some tumor responses were spectacular. The drug was less effective for bone deposits. In this study 12 of 33 patients (36%) receiving 10 mg of tamoxifen twice daily showed a definite response while a futher 8 (24%) showed a partial response. A definite response was seen in 14 out of 35 (40%) receiving 20 mg twice daily and a partial response in a further 13 (37%). The total response for low dosage was 60% and for high dosage 77%.