Long-term survival of patients with breast cancer receiving endocrine therapy is poorly understood. In a recent study aimed to determine the impact of adjuvant tamoxifen in patients with lymph node–negative, estrogen receptor–positive/ERBB2-negative breast cancer, Anna Nordenskjöld, MD, PhD, and colleagues from Karolinska Institutet and University Hospital, Stockholm, determined that there was a significant long-term benefit from tamoxifen observed in patients with larger, lower-grade, and progesterone receptor–positive tumors. Their results were published in JAMA Network Open.