The efficacy of tamoxifen for the 75% of postmenopausal breast cancer patients with hormone receptor positive disease was initially demonstrated by the mid-1980’s, and dozens of trials have shown that such women randomized to 5 years of tamoxifen therapy have a 47% reduction in breast cancer recurrence and 26% reduction in mortality at 10 years compared to placebo (Early Breast Cancer Trialists’ Collaborative Group 1998; Early Breast Cancer Trialists’ Collaborative Group 2005). The gene discussed is NR4A1; the disease is breast carcinoma.