However, patients receiving adjuvant tamoxifen would still experience breast cancer recurrence; according to the meta-analysis by the Early Breast Cancer Trialists' Collaborative Group, five years of adjuvant tamoxifen safely reduces 15-year risks of breast cancer recurrence and death, with the cumulative recurrence rate reaching 33% in 10,645 women (100% ER-positive, 44% node-positive, 51% chemotherapy) [6]. This evidence concerns the gene ESR1 and breast cancer.