The American College of Surgeons Oncology Group Z1031A trial is one of the latest to provide support for the assessment of prognosis based on tumor characteristics after neoadjuvant endocrine therapy in postmenopausal women with ER‐positive breast cancer.32 Ki67 index was used to decide subsequent treatment after 2‐4 weeks of neoadjuvant therapy with an aromatase inhibitor (anastrozole, exemestane, or letrozole); patients with Ki67 index >10% were switched to neoadjuvant chemotherapy. The gene discussed is CYP19A1; the disease is neoplasm.