Tamoxifen: Dr. Jekyll and Mr. Hyde?

Extract

Without regard to patient selection, other than the eligibility requirements for entry into the studies, worldwide overviews of prospective clinical trials demonstrate that adjuvant tamoxifen reduces the annual odds of death for women with invasive breast cancer by approximately 15% over 10–15 years ( 1 ) . These data raise the provocative question: Should all patients with invasive breast cancer receive tamoxifen? Application of tamoxifen, irrespective of selection factors, would result in overtreatment of an enormous number of women who would not benefit to ensure the benefits for those who do. Although acceptance of tamoxifen treatment is very high, the ability to measure its target, the estrogen receptor (ER), has permitted application of this drug to those most likely to benefit: patients whose tumors express ER ( 1 , 2 ) . Thus, ER is one of the few tumor markers that is recommended for routine clinical use by the American Society of Clinical Oncology ( 3 ) .