In cases involving locally advanced tumors, characterized by factors such as a tumor diameter greater than 5 cm, axillary lymph node metastasis, or unfavorable molecular types (like HER-2 positive or triple-negative), or in patients with a tumor size-to-breast volume ratio that complicates breast preservation, preoperative neoadjuvant chemotherapy is frequently preferred. The gene discussed is ERBB2; the disease is neoplasm.