Optimization of Dynamic Neoadjuvant Therapy Strategies for HER2-Positive Breast Cancer Based on HER2-PET/CT Molecular Imaging

Inclusion Criteria: * Voluntary participation with written informed consent obtained prior to any study-related procedures * Age ≥ 18 years, male or female. * Eastern Cooperative Oncology Group (ECOG) Performance Status of 0-1 * Histologically confirmed HER2-positive (IHC 3+, or IHC 2+ with ISH amplification) stage I-III (cT1-3/cN0-2) breast cancer * Tumor diameter ≥ 1.5 cm assessed by imaging, with at least one PET-evaluable lesion present * Patient must have known estrogen receptor (ER) and progesterone receptor (PR) status. For Arm B, ER expression ≥ 10% and must be strongly positive. * Adequate bone marrow, liver, and renal function: WBC \> 3.0 × 10⁹/L, ANC ≥ 1.5 × 10⁹/L, PLT ≥ 100 × 10⁹/L, Hb ≥ 10.0 g/dL; total bilirubin ≤ ULN (excluding Gilbert's syndrome), ALP ≤ 2.5 × ULN, AST/ALT ≤ 1.5 × ULN; creatinine ≤ 1.5 × ULN or creatinine clearance ≥ 50 mL/min. * Patients who participate in the trial have good compliance and are willing to comply with the follow-up visit. Exclusion Criteria: * Prior treatment with any chemotherapy, anti-HER2 therapy, radiotherapy, or endocrine therapy, etc * Locally advanced (cT4/cN3) or bilateral breast cancer * Patients with known allergies to any active ingredients or excipients of investigational medicinal product * Other malignancy diagnosed within 5 years prior to enrollment, excluding cervical carcinoma in situ and cured melanoma skin cancer * Left ventricular ejection fraction (LVEF) \< 55% * Uncontrolled hypertension (systolic \> 15…