Previous studies suggest that among patients receiving trastuzumab monotherapy, a HER2/CEP17 ratio \>7.0 (ultra-high expression) is associated with poorer disease-free survival (DFS). Dual-target therapy (trastuzumab + pertuzumab) has become the standard treatment for high-risk HER2-positive breast cancer; however, whether it can predict outcomes in patients with ultra-high HER2 expression remains unsupported by clinical data. To analyze the clinicopathological characteristics and prognostic relationship between the HER2 ultra-high expression group and the normal expression group in non-metastatic HER2-positive breast cancer patients who received dual-target therapy.
Age ≥18 years.
Pathologically confirmed primary breast cancer, clinical stage I-III (AJCC 8th Edition).
HER2-positive status confirmed by FISH testing (per ASCO/CAP guidelines) with available HER2/CEP17 ratio.
Received at least one dose of dual-target therapy (trastuzumab combined with pertuzumab) in the adjuvant or neoadjuvant setting.
Presence of distant metastasis (Stage IV) or contralateral breast cancer at initial diagnosis.
Previous anti-HER2 targeted therapy prior to dual-target treatment.
Missing key clinical data (e.g., HER2 FISH results, treatment regimen, surgery date).
Carcinoma in situ or occult breast cancer, non-primary breast cancer, or concurrent other malignancies.