The USO1062 phase III trial enrolled 2,611 high-risk early breast cancer patients defined by tumor size, nodal status and/or negativity for hormone receptors (T1–3, N1–2, M0; or T>2 cm, N0, M0; or T>1 cm, N0, M0 and both ER- and PR-negative), who were randomized to standard anthracycline/taxane chemotherapy with or without the addition of capecitabine. Here, ESR1 is linked to breast carcinoma.