Neratinib in Extended Adjuvant Treatment for HER2+ Early Breast Cancer With pCR But High-Risk Features: A Hebei Multi-Center Real-World Study

Inclusion Criteria:

1. Age ≥18 years, female
2. Clinical stage ≥cT3 or ≥cN1, regardless of hormone receptor (HR) status
3. HER2-positive: HER2 IHC 3+ or IHC 2+ with ISH+
4. Achieved pathological complete response (pCR) after neoadjuvant therapy
5. Completed 1 year of standard adjuvant therapy (including trastuzumab), with ≤6 months between the last adjuvant treatment and starting neratinib
6. No evidence of recurrence or metastatic disease (confirmed by clinical/imaging exams after completing standard adjuvant therapy and before starting neratinib)
7. Left ventricular ejection fraction (LVEF) ≥50%
8. ECOG performance status 0-1

Exclusion Criteria:

1. Hypersensitivity to any component of the investigational drug
2. Inability to swallow oral medication
3. Participation in another interventional clinical trial within 4 weeks before enrollment, or planned participation during this study
4. Use of any investigational drug within 14 days prior to treatment initiation
5. Concurrent chemotherapy, radiotherapy, immunotherapy, or biologic therapy for breast cancer
6. Severe psychiatric disorders preventing compliance with informed consent, treatment, or follow-up procedures
7. Pregnancy, lactation, or plans for pregnancy in the near future
8. Other significant medical conditions or laboratory abnormalities that, in the investigator's judgment, make participation unsuitable