Fasting-Mimicking Diet as an Adjunct to Neoadjuvant Chemotherapy for Hormone-Receptor-Positive Breast Cancer

Inclusion Criteria: * Histologically confirmed ER-positive , HER2-negative invasive ductal carcinoma meeting at least one of the following:1)T1c-T2 N1 with histological grade 2 (ER 1-10%) or grade 3. 2)N2-N3 or grade 3 and/or Ki67 ≥40%. 3)T3-T4 * Age 18-75 years at enrollment * Body mass index (BMI) ≥18.5 kg/m² * Adequate hematological function:1）White blood cell count\>3.0×10⁹/L.2)Absolute neutrophil count ≥1.5×10⁹/L.3)Platelets ≥100×10⁹/L. * Adequate organ function:1）Total bilirubin ≤1.5 × upper limit of normal (ULN).2）ALT/AST ≤2.5 × ULN. 3）Alkaline phosphatase ≤5 × ULN.4）Creatinine clearance ≥50 mL/min-1) * ECOG performance status 0-2 * Willing and able to provide written informed consent Exclusion Criteria: * Prior history of any malignancy (including contralateral breast cancer) * Received any prior neoadjuvant chemotherapy cycle for current diagnosis * Uncontrolled endocrine disorders:1)Diabetes mellitus requiring insulin or oral hypoglycemics.2)Hyper/hypothyroidism requiring medication * Active autoimmune disease requiring systemic immunosuppressants * Current use of antipsychotic medications * Known hypersensitivity to FMD components (e.g., soy protein, milk protein, nuts) * Pregnancy or lactation.